Oh, if you could please let me know, welcome to Learn English Live and let me know in the chat if you can hear me and see me. I would greatly appreciate it, so if you can give me a thumbs up or say, yes, I can hear you, I can see you, that would be fantastic. So let's take a look and see who we have here today in the chat. Let's see, so we have, of course, the winner of the Gold Star, Anna, was the first to arrive today. Thanks for stopping in early. Good morning to you. It's evening time. That is 7 p.m. Central Standard Time in my time zone and my family is wrapping up dinner right now, so I can still hear some noises that my son, he's doing his chores. And hello, Gritrudis, welcome. Let's see, we've also got Alex, Alex, hello, Jonathan, Samira, hi Samira, how are you doing? Alex, I am not talking about at tonight, at will be, that should be a different lesson. Rohit, welcome Rohit, hello. Thanks for stopping in and Samira says yes, I can see you in here, thank you so much. So let me know where you are located today if you would like to share that information in the chat. Natalie, great to see you, thanks for joining, hello Layla, good morning Layla. For some of you I know it's very early in the morning and for others it would be dinner time or maybe late evening, so thank you, okay, so Gritrudis, if you say you've had a lot on your plate you would say I have a lot on my plate. If you say I have a lot of food on my plate then people would think that you literally have a plate with a lot of food in it. The slaying or the idiom would be I have a lot on my plate right now. Dan Samira says she's perfect, I'm doing great today, oh gosh, Alex, 2am, yikes. You and Samira are night owls, Samira doesn't get a lot of sleep. So let's 4.32, I wake up around 4.30 to teach 2 days a week and that is really hard. So welcome everyone, if you are new to this lesson my name is Sherry and I am an online teacher and I am so excited to kick off the new year with a lesson with you. So let's take a look at our topic for this evening. Welcome, great to see you. We are going to talk about the articles today. Now the articles are often something that is reviewed early in a person's English language journey but I wanted to start with the articles because I have many students that I interact with online who they forget to use the articles in their sentences, often in writing and sometimes even in speaking. They will not use the articles, they will omit the articles. So let's take a look at the rules for using the definite and indefinite articles which are A and the. Livestream, I'm not going to scream on this live but I will have a live stream. Jonathan, you are in the same time zone as I am but your weather is much nicer in your beautiful country. So let's talk about what are they, what are the articles. We'll begin with a definition. The definition is that articles are words that describe a noun as specific or unspecific. So let's get started with talking about the types of articles. We have both the definite and the indefinite articles and the word the is the definite article. So we're going to talk about that Alex in a moment, just hang tight, we'll get to that at the towards the end of the lesson. The word the is used and a way to limit the meaning of a noun to one particular thing. So one particular thing is when we would use the definite article of the. It can be used with singular nouns, plural nouns and uncountable nouns. So let's remember when a noun is uncountable that means literally it's difficult to count but for examples we would have something like sugar, sugar. You cannot count all of the grains of sugar. You would not talk about water, you'd say I would like some water. You don't say I would like three water, no. Now you could say I would like three glasses of water. So the is for a specific thing, yes. So for example, are you going to the game tomorrow? In this example, game is our noun and the is the article for game. The game is a specific game tomorrow. And when you would use this sentence, your listener understands the context. They know the game is only one game. There's a big game tomorrow at your school or university and your friend says, are you going to the game tomorrow? And everyone knows what the game is. It's the big game that everyone wants to go and watch. I hope that in the coming months that schools will be able to return to having extracurricular activities for students. So let's now talk about the indefinite articles. The indefinite articles are used with a noun that refers to a general idea rather than a particular thing. A general idea rather than a particular thing. Our examples for the indefinite articles would be the words a and an. The letter a, but it's pronounced as the schwa, a, a. Okay, so this is a nose. This is a nose, an, an. So when do we use a or a and an? When do we use them? We would use the a when it precedes or is before a noun that begins with a consonant, okay? So a consonant sound, a car. So I have a car, a car. So we would use the article a or a when the word after our article starts with a consonant, a car, okay? So let's look at some more examples and we have some exercises to do later. So hang in there. More examples would be a storm.    It's not a specific child, it is a non-specific child. So let's take a look in the chat. We've got students who are listing some sentences perfect. So we have, yes, Jonathan is an avid bicyclist. He says I have a bike and Layla says your car is a cute car. Thank you. My toy car is a cute car. Carrie, hello. Can I say a snow? Can I say a snow? If you were to say a snow storm, you would say we're expecting a snow storm, yes. But snow is a collective noun so you wouldn't need to use that article. You would say it is going to snow or I like snow, snow is coming. So let's do an exercise. Now I'm going to look here because I have a friend who said that he was going to attend the lesson and I wrote this sentence for him but I don't see him here in the lesson yet unless he's being quiet. We're going to choose in the chat, I want you to type your answer to this sentence. I have, is the answer, I have a friend in Ecuador, is it or is it, I have a friend in Ecuador. Samira is fast on the keyboard today. So let's take a look. I have a friend in Ecuador. I have a friend or I have a friend in Ecuador. Yes, Rohit, welcome. Race, yes, excellent. Alright so let's look in the chat. We have Anna when we are referring to a single of uncountable nouns. We use a or an for example, the hair. Now remember we need to talk about specific.  So I want to do something to my hair. We wouldn't really say a hair unless I have a hair in my mouth. I have a hair in my mouth. So we would use a and I think I answered your question there. Alyssa, great to see you here Alyssa. We are talking about the articles today Alyssa, a and the definite and indefinite articles. So Anna, I hope I answered your question there. I had to think it through. I haven't done a live lesson for a while. So now let's review when to use an. We use an when it precedes a word which is a noun that begins with a vowel. We use the article an when it is before our noun that begins with a vowel. So we have an egg, an egg. Hello, hello, hello, welcome from Poland. That's excellent. Tosia, is it Tosia? Let me know if I pronounced your name correctly Tosia or Tosia. I'm not sure. I really like to make sure that I can pronounce students names correctly. My name is spelled very and a little unusually and a lot of times people will say cherry with the ch sound. Specifically many of my Latino friends will say cherry. But my name starts with the sh sound, sh, sherry, even though it's spelled with ch. Yes, Alex. We're going to talk about that as well. Hang on there, Alex. Just hang on there. I know it's 2 a.m. Teresa. Okay, Teresa. Welcome Teresa. Thank you for coming to the lesson. So more examples that we have when we would use an. We have an elephant, an elephant. We also have an apple. So now I have a question. Let's type in the chat another example of when we would use an. Give me the word an followed by a noun in the chat and let's see what you students can come up with here today. I have not had my dinner yet, but my son, he made eggs for dinner as part of our dinner. Yes, we're going to talk about that, too. Hang in there, guys. We're going to get there. We're totally going to get there. An angel. Yes. An eagle. An artist. Perfect. Excellent. And I do want to call attention to thank you so much for our special subscribers. So we've got Jonathan and Anna and Layla and Dwi. Thank you so much. Your special subscriptions to our channel help Robin do more of what we are doing with offering free lessons. An animal, an excellent student, Natalie says an airplane, an octopus, Alex, an actress. Samira, would you like to be an actress? When I was young, when I was in grade third grade, I was the lead in a play. And then later in high school, I was in a play as well. It was a lot of fun. An event, an awesome night. An awesome night is an awesome night because I get to share it with you, with you, the students. I'm so excited to get started again. All right. So I think you guys have done an amazing job using the article and correctly. So let's go ahead and take a look at another exercise here. I understand, Aviar. No worries at all. An injection. Ooh, I received an email today that I am able to get the vaccine. So I need to think about that. That will be an exciting moment. An aunt and Layla says, I am an artist. Yes. Okay. So let's take a look at our exercise here. And if you would please type in the chat box again. It's very important to be an active learner. So instead of just listening, watching and reading what other people are saying, go ahead and type in the chat. That helps you be an active learner. She's reading an old magazine or she's reading an old magazine. Then we have, I bought a pair of shoes or I bought an pair of shoes. So an old magazine, Alex says, and Grotrudis is giving us an example of an hour, which is one of the tricky words we'll talk about in a moment. A pair of shoes. I also liked, but my mother was disagreeing, so I chose English, but she still doesn't like that. But I love it. Okay, Samira, I need to go back and see what that comment is referring to. She's reading an old magazine and yes, good. I love shoes. Now I am not a person that, I don't spend a lot of money on clothing. When I was younger, I did, but I don't anymore. I have four kids, so I just can't, but I love shoes. I love nice, comfortable shoes. I don't spend a lot of money on them, but that is my one thing I do like to buy, handbags and shoes, but shoes is at the top of my list. I also like sunglasses. I'm kind of an accessories kind of person. Accessories are things like belts, shoes, sunglasses, handbags, those are all accessories that we wear. She's reading an old magazine, an old magazine, a pair of shoes that is correct. That work. And so let's continue. Yes, Alyssa, I'm a little bit of a shoeaholic. Yes, Leila, I hope you're able to get some new shoes. I have to tell you, this is my medical side of me coming out. I do have some medical background. It's so important to wear comfortable shoes that support your feet. If your feet are not happy, your body will not be happy. So it's important to wear comfortable shoes. Oh, yes, okay, refers to being an actress. Thank you. I understand now. So now let's get to the tricky situation. Alex was asking, Gertrudez mentioned it as well. So let's talk about the tricky situation. Sometimes the noun may start with a consonant, but it sounds like a vowel. And Gertrudez used this word in one of her examples. It will take me an hour to finish. So if we look at the word hour, hour starts with the letter H, which is a consonant. But it doesn't sound like, it sounds like, ow, the vowel sound, ow, it will take me an hour to finish. Yes, so it will take me an hour to finish. This is one example of a tricky word that starts with a consonant, but it sounds like a vowel sound. So you need to go with what it sounds like. If it sounds like a vowel, then we need to use, and if it sounds like a consonant, we use a, or a. So yes, that is correct. You would say, so if we're going to talk about university, what sound does the first letter make in the word university? Yeah, yeah, which is a consonant sound. It is spelled with the U, but it sounds like yeah. So you would say, a university, a university, and an honest man, an honest man is perfect because again, H is a, a, and Layla says I need an hour to get to the hospital. Yes, that is correct. A university, Samira, yes, I'm going to go to a university when I graduate from high school. Yes, it has the Y sound that is correct. And Julie, welcome Julie, welcome to the page, welcome to the channel. So yes, MP3, the letter M, we have the letter M, but it starts with eh, eh, the vowel sound. So you would use an, an honor. Anna, it is an honor to be teaching you this lesson. Yes, Alex. So let's continue.  Okay, so let's continue with it's tricky. Every time the noun begins with the vowel, but it sounds like a consonant. So for example, and I need to get my letter out here. When I was young, I wanted to ride a unicorn. I have all these fun letters that I use with my students that are the shape of animals and different fun things. And my U has a unicorn on it. Let's see if I can find it. Here it is. I wanted to ride a unicorn. I collected unicorns. I had a stuffed unicorn that was very soft and its horn was golden. So we need to use ah, the letter A, the article A, before the word unicorn because the U makes the, yeah, yeah, sound, unicorn, ha, a match, yes, because mm, makes the consonant sound. So let's practice some together.  This is, we started off with maybe an easier lesson because I know last year students would say, oh, this lesson is kind of hard. So we're going to start off a little bit slower. Yes, I like that. I am going to go on a European vacation. E, it starts with E, Europe, but it sounds like year, year, perfect. If you would say, Sherry is an honorable woman, you would use the word honorable. Well, there he is, Andreas decides to make an appearance. You missed your sentence earlier. Um, Alyssa asked the same question, yes, a university, and we have a, we saw a bad accident last night. It's always terrible when you're driving and you come upon an, an accident, the scene of an accident. We saw a bad accident last night. Perfect. Okay. And how about this example sentence? I heard a and or the, I heard a and or the amazing story today. A eulogy. Good. Alyssa. Yes. Andreas. A unique situation. Yes. Hmm. You are very unique and I heard an amazing story today. Yes. I heard an amazing story today. So let's flip it a little bit. Okay. So let's flip it. And we could, if the context was provided to the listener about an amazing story, then you could use the word the, I heard the amazing story today, right? If the context is provided, someone is telling you a story, you could say, Oh, I heard the amazing story today. Also the Bible is sometimes called the amazing story, but for this sentence, the answer, the correct answer, I heard an amazing story today. Okay. So let's take a look at this example sentence. Now remember, we need to talk about definite and indefinite, specific, not specific or unspecific. That is blank guy. I told you about that is guy. I told you about, hmm. Let's look at the context of the sentence. You've got some answers coming in. Carrie, I would love to know where you're coming from. If you feel comfortable sharing, I don't think I've met you, Carrie. Andres, that, I think maybe you typed incorrectly, the, okay. So yes, this is a sentence that I have used recently.  That is the guy I told you about. It's a specific person. That is the guy I told you about. Okay. That is the guy I told you about. And you know, flip side. That is the girl I told you about. That is the story I told you about something very specific. That is the guy I told you about. Okay.  You can do it. This is easy peasy lemon squeezy, right? Okay. In the chat box, write a sentence using the definite article. So in the chat box, I want you to write a sentence using the definite article. So let's take a look while you're doing that. I am going to have a drink. Remember you can support the channel here. The information is in the links up above. You can also find Robbins. He's got a website now and we have our information there. I'm on TikTok here on YouTube, Learn English Live and Learn English with Sherry. And also I'm on Instagram. Follow me if you have not, please. Okay. We use the for specific things. Yes. The other person knows about it. Okay. So, Samira, with your example, the word the is referring to other. And Apple a day keeps the doctor away. Okay. And now we're working on the definite article. Okay. So the definite article would be the. The. Yes. So if you were to say, um, I want to go to the USA. I want to go to the USA. That's a definite, a specific country. Last night I saw cat. The cat was too poor. Okay. Yes. But Layla, I would like for you to change your sentence. Okay. Um, you're using, I think maybe those could be two sentences. Last night I saw a cat. Period. The cat was too poor. Or you could say, last night I saw a cat, semi-colon, the cat, it was too poor. The cat was too poor. Hello, Diego. Great to see you. Welcome. We have few people from Ecuador in the group tonight. Everyone has problems in a life. Okay. Dweet. You need to use the definite article, which is the. Okay. The UK, Alex, yes. This is the dog I found in the box. Yes. So the cola is, yes. So you could say, um, um, actually I would like to change your sentence. You would not need to use an article in that sentence. You would just say, cola is Sherry's favorite drink. But if your question is, is cola Sherry's favorite drink? Ah, phrases and idioms. Great. Yes. I'm actually, I have reading through a book on that as well to help me with some lessons. Ah, I bought the book. Yes. That you advised me recently to purchase. Yes. Um, Javier, um, questioning, you're saying, ah, maybe you're behind in the lesson. I don't know. Everyone's internet speeds a little different. Joseph likes to wear a hat. Okay. That's the indefinite article. We want to use the definite, which is the, I'd like to go to the UK. Yes. An apple a day keeps the doctor away. Yes. Okay. I was, do we, Anna, I apologize. I was looking at Apple. Yes. You are correct. The president of USA is Donald Trump. Yes. Um, just for a couple more days. Hello, Alex. Nice to meet you here. So let's move on. Now let's use one of the indefinite articles. Now remember the indefinite articles are a and an or a. Yes. That is correct Theresa. My sister is in the kitchen. So let's write a sentence in the chat box using an indefinite article a or an. The apple is not far from, okay. So Alyssa, that is one of my favorites as far as ADMs go. You would say the apple doesn't fall far from the tree. The apple doesn't fall far from the tree, which means that a child is similar to the parent. And so in my school, I have teachers that I work with who have been teaching a long time. I have not quite been teaching long enough to teach children of former students, but other teachers have. And so if they have a student and they also taught the parents, they may say the apple doesn't fall far from the tree because the parent and child may have been similar students in their classroom. Okay. So let's take a look at people in the chat again. The people wear, okay. So jewelry is an uncountable noun and it's not being specific here. So you would say the people wear jewelry to make themselves more attractive. You would not use the. I love to read the book that you suggested me. Great Layla. That's perfect. So that was the building which was destroyed last month. You're specifically referring to an event that happened with one specific building. Yes, Samira. That is the, but we're using a and an. This is an exception to the rule. Great. We. Anna.  So I don't get flowers from anyone.  Flowers. Thank you very much. I met a boy. Layla, did you really meet a boy? Playing piano is an awesome hobby. Yes, it is. I love playing piano. I have one sitting right over there, but I haven't used it and I have not played in many years. Oh, great. I'm so glad that this is a beautiful English YouTube channel. Thank you, Andres. You make me blush. Gratuitous.  Yes, it's not a specific ball. You're just, yes, that's perfect. Michael Jackson was a famous singer, mm-hmm. So Alex, so when you say watching Sherry's Lawsons is a unique experience, be careful because your sentence is grammatically correct. It's perfect, okay? But I just want to share with you, sometimes the word unique when it is used, it can be interpreted as meaning negative. Sometimes when people say, yes, it was a unique experience. What their meaning is, it was unusual. It was different. I didn't really like it, but your sentence is grammatically correct. And then other times when people say it was unique, they mean it in a positive manner. Yes, Layla. There's a song by Beyonce that I really like and I can't sing because I'll get in trouble with YouTube. Plus, I'm a terrible singer, but it's called If I Was a Boy and it's a really interesting song. I like it. I like it a lot. You received, I received an exclusive invitation from a friend of mine. Oh, Alex, no worries. That's why I'm sharing this just so you'll know because I didn't know when I was meeting with my friend that a word in English, it sounds the same in Spanish and that word means something totally different. Salmon is a fish, but apparently it's something completely different in another language. Ah, thank you. Thank you very much, Jui. Great sentence. We were driving home yesterday. We saw an accident. The accident was serious. Rockstar. That's a great example of how to go from a non-specific situation to a specific, using an indefinite to a definite. All right, great exercise. Okay, so now let's move on to examples of tricky words. Someone already mentioned earlier how I think it was, they said, I'm going back in the chat to see. Somebody talked about M and how you would have to use, we had a university, an hour. I'm not finding it. So do you guys know the candies, M and M's? M and M's? M and M's are a chocolate candy. And I have a story about M and M's that maybe I'll share. M and M's, eh, eh, it starts with a vowel sound even though it has the letter M. So the candy actually has M and M on the label. So you would say, if you wanted one, you'd say, can I have an M and M? And you want one little piece of candy, can I have an M and M? URL, URL is an address on the internet. We would talk about URLs. And the letter is U, but it starts with the yes sound, U-R-L. And then yes, university, very unusual. Oh, an MP3, thanks Anna. I'm finding that now. So, I cute. Javier, I'm not sure what, I think I know what you typed. In the group's point of view, he is an infamous guy, ah, infamous. Great word. Layla, I am wearing an old jacket. Old jackets are the best. I had a jean jacket once that was my father's, and so it was very old. But it was so worn and soft, and it was frayed, it was so cool. And then a boy ruined it. He wrote on it, he had a crush on me, and he wrote on it in junior high. And it ruined the coat. I was so sad. Ah, okay, an MP3, yes, an MP3 player. So what about university? I want to talk a little bit about university. So when we talk about the word university, and remember if it's an indefinite article, we're not referring to anything specific. I want to go to a university when I graduate from high school. But let's say that you want to go to a specific university that is in your local area.  So do we, yes, okay, I see that, okay, an M&M, a-u-r-l, a-u-r-l. Because u starts with the letter u, but it sounds like ya, ya, the y sound, okay. So let's continue. All right guys, we got through this lesson really quickly, the Oxford University, yes. So I also want to talk about when we are pronouncing our letters. So let's do something a little bit unusual. I don't usually stray from the lesson too much, but let's just go ahead and we will add a new slide. Because I'm feeling kind of, kind of, kind of crazy. So let's, let's branch out a little bit here. And we will talk about the pronunciation of the, uh, so if we see the a, we would say a car, a car, but it's actually pronounced a car. This is a car. Now in English, if you want to be really specific and stress something, you could say, I want to go get a car because you want to be really specific about it. It's something that's stressed. But typically in conversational speech, you would say a car. This is a car. This is a fast car. The same thing goes with the word the. So if we were to talk about the word the, and I have a specific example that I want to talk about with this. So pronunciation for the. So again, T-H-E, so we've got the schwa at the end, the, or the a sound. So we'd say the university. Now there are certain instances where people will change it to the when they want to stress something. So for example, oftentimes, uh, let's see, last night was the college football championship game. Not soccer, but actual football, American football. It was last night. And at the beginning of a game, all of the players on the team that are on the starting roster. So they're the players who are going to begin the game on the field. They announced them. They will show their picture in a video and the player will say, my name is Brett Johnson and I attend the Ohio University. But typically people would say I go to the university. But when they're talking about the specific university and they are wanting to stress because they're really proud of where they attend. I attend the Ohio State University. Yes, that is correct, Leila. In the evening. Yes. Okay, so the pronunciation issue is, is not something that is a hard and fast rule. It's something that you could do, but I will tell you in conversational running speech, the letter A, the article is often most often pronounced, uh, mm-hmm. Okay, so I want to open up the floor. Do you guys have any questions for me about the lesson or I can give you guys about five minutes? If there are other questions that you would like to ask, I will open up the floor for that. Feel free to ask away. Let's just see who's in the chat here. While I am waiting for that, I want to take a quick drink.  My dinner, I can smell it. I'm going to have some bacon and scrambled eggs and toast. So let's see what we have here in the chat. Thanks again for stopping by Learn English Live. I do live lessons every Tuesday at this time on Learn English Live. I also have live lessons on my personal YouTube channel, which is Learn English with Sherry. And I am always producing videos for my TikTok and Instagram. Those, of course, are very short lessons. So let's take a look and see if anyone has any questions. If you guys would like to talk about anything else, phrasal verbs or idioms. I would be happy to do that as well. Let's just see here. Looks like we have a variety of students from some new students and some students who are definitely returning. On the flip side is like the other hand. See you later, Jonathan. Thanks for coming. And hey, Jonathan, I'd love to see a photo of your newborn daughter sometime. Yes, on the flip side. So you could say, um, I'll see you on the flip side means that I'll see you next time or I'll see you tomorrow. Yes, I wish we had a washing machine. Mm-hmm. That is correct, do we? All right, guys. Yes, Samira, you do. Thank you so much for the love, Samira. You're great at sharing my posts with the WhatsApp group. If you would like to participate in a chat group in the links on Learn English Live, there are links for WhatsApp groups that Robin Shaw hosts. He's a great moderator of those groups. OK, so that is perfect, Layla. Great question because I often will hear people say, put this on the TikTok. OK, so TikTok, you're not going to use the. You're going to just say, put this on TikTok. You're not going to say, put it on a Twitter. You're just going to say Twitter because it's very specific. You're welcome, Gertrude. You're welcome. Mm. OK, so I use OBS for my streaming. And I have used some virtual backgrounds before, Alex, but I don't like how it pixelates. You know how it's when you move, because I tend to move a lot and it gives that distortion. Also, I have a Mac, so I have to be really specific on what type of streaming I use and also so I can't use Manicam and things like that. But good point. Thank you for sharing that. All right, guys, I think I'm going to go ahead and wish you all a great day. Good evening. Good night. Thank you so much. Make sure that you check back because I will post a homework lesson for you tomorrow on this feed. There will be, it takes about 24 hours for the lesson to show up on Learn English Live. Come back tomorrow and I will post a homework lesson and anyone who does post, I always respond on my social media or here on YouTube. So please make sure you do that. Yes, Samira, I understand. Thank you so much, everyone. Oh, thanks, Natalie. Let me know how you're doing. Do we an usher and usher? There are unused. There is a user. Okay, there are ushers and usherettes at the wedding reception. Is it correct we use it? We use and twice. You would not use and because yuh is a consonant sound. You would say there is a usher and usher. Okay, you're right. It's us. So user, you spelled it wrong. I'm sorry. Usher is U-S-H-E-R. Okay, cool. Yes, see you. Thank you so much, guys. Keep practicing. Don't give up. You can do it. Have a great one. See y'all later. Thanks for joining. See you next week. Goodbye.


Please join me in welcoming to the stage, Douglas Atkin. Thank you. Hi. Thanks very much for having me. So, despite some who think otherwise, notably some politicians, not David Chu, and some incumbent industry lobbyists, we at Airbnb and Piers think the sharing economy or pit-a-pit economy is a jolly good thing. We think it's such a good thing, in fact, that it probably will and it certainly should become a dominant global economic model. And the reason why is because the last economic model, the production and consumption one, promised much but chronically under-delivered. It promised economic independence. It promised freedom. It promised self-actualization. And yes, even happiness. And I know this personally because I'm the devil, actually. I worked in advertising for decades in London and New York and I helped tell millions of consumers, which is a word I've always hated, that happiness can be found in a credit card, a car or a condom. Well, actually, maybe it can be found in a condom, but not always. But not really in a credit card and a car. The sharing or peer-to-peer economy deserves to succeed, I believe, because the very things that became the casualties of the old economy, the last economy, things like community, things like control and economic independence are actually built into the very infrastructure of this new economy. You can't do this new economy without creating community, without buyers and sellers meeting each other, without hosts and guests engaging with each other. It's part of the very fabric of the economy. Yet in the last one, especially when I was in advertising, I would see surveys every year depressingly track people saying, I wish I could spend more time with my neighbors. I wish I could spend more time with my family. And as commute times increased, the amount of socialization and community decreased. So here's a short video I'm going to show you. It's about two minutes long of some workshops and focus groups I did about a year and a half ago now in San Francisco and New York, where I talked to some hosts and guests of Airbnb. So it's not representative, I know, but it is indicative. And the common themes you'll hear in this, and we hear all the time, is from hosts stories of transformation. This economic independence has enabled them to basically have a regular income that labels them to do the things they always wish they could have done. You know, write that book or start that business or like Rob in New York. He's a real estate agent, hates it. Now he shares his spare room, he's able to focus, go to school for acting, for example, which is something he always wanted to do. He's happier. And also from, you'll hear from guests as well. What we hear all the time from guests, and this is sort of the idea really, is that they now feel that they can belong anywhere. That they're almost like the world's local because they're living with locals and living neighborhoods and small businesses that they would never do if they were in the centre of town staying in a hotel. They feel at home wherever they go basically. So let me just play you the short video. In my life before Airbnb, I always felt very beholden. I felt very beholden to the company that I was working for. And now I just feel completely free. It's my husband and I, and we're running this business. I get a lot of personal joy out of hosting. It's my favourite thing to do. All of a sudden I feel like human again. I feel like more of like myself. This has allowed me to just welcome like that traveller feeling into my home. I'm definitely a lot more just at ease with myself and I'm definitely more optimistic about like approaching people. And now I live with a roommate from Airbnb and he's really one of the coolest people I've met. So this allowed me to have the life with that. I knew that I was capable of, that I knew that I wanted. I just couldn't figure out financially. It has also motivated me and my personal service to get my contractors licensed and start building tree houses. I also have a picture of my 12 year old son and he's benefitting from meeting all these people. By discovering Airbnb we learn what it was like to really be a local. Actually it kind of unleashed this adventure in me that I didn't know existed. Can you give me two words of what you were like before and two words of now? Shy and a follower. And what about now? Outgoing and fun. And this has been probably the most thrilling thing that I've done. I'm actually doing something that I've been wanting to do for a long time. I'm taking printmaking classes. I tend to host a lot of people in the arts community. It's been a really nice influence on me having confidence to do this kind of thing. This bracelet is from a friend I met on Airbnb. This sweater is from Stoneman. I was there because I didn't know about it. I really don't know about it. It's just, I guess who I am. It's a few words. Who would you describe how you are now? I am me. So I'm sorry about that music in the background. It kind of was a bit sloppy. I think you get the idea that we hear literally all the time these stories of transformation. It's very, very encouraging. So the reason why I think we're beginning to hear these things is that there's a decentralization of wealth and control and power. And that's at the heart of why the peer-to-peer economy is better than the pure production consumption economy where wealth, control and power were absolutely centralized. That's why this economy is a better economy in my view. When I worked at Meetup, I became a huge fan of self-organization and decentralization. Given the tools we saw, people do amazing things when they self-organize together. So Airbnb, of course, and most of the other platforms is a decentralized marketplace where most of the wealth is made and most of the community is self-organized. We took this a step further a year ago, well, actually about six months ago. And we also decentralized the community platform and self-organized it on Airbnb. So I just want to actually do a quick romp through this to show you how that's working. So we launched this platform about six months ago and it's where our hosts start, run and join their own communities. We don't moderate them. They're not our communities. They're our host communities. Totally owned by them. So just to give you an idea, this is a random selection of communities that emerged in New York. So there's Brooklyn Host Collective. There's even the New York City Sharing Economy group. There's hyperlocalized ones. There's legalized sharing in New York. This is Evelyn here and Chris, who I think are here in the audience somewhere. Awesome hosts who started that. This is the one in Barcelona. They're all over the world. So there's ones about hosting, and there's also ones like this one here, which is totally focused on laws and taxes. And this one is about taking political action, the one at the top in the middle there. And this is kind of what the homepage looks like, basically. This is one of them called the New Host Forum. It has 5,396 members. And we're here to learn from each other through supportive and effective feedback, online coaching and membership. So far about 60,000 hosts have joined these and there's about 50,000 posts. But the most gratifying thing is that, and this is a key indicator I've learned of any successful community, is that you can tell you've got a successful community when there's lots of mutual support, when the members are helping each other because they feel a mutual responsibility and affinity and a relationship with each other. So we see this in things like, this was from yesterday, I think, three days ago, my latest good idea where people putting up good ideas and commenting, but they're also giving each other practical help about things like the dark and curlies. It's an inevitable consequence of hosting and it has to be discussed thankfully there and not with us. It's very illuminating, actually, reading these posts. So another way that, oh, and this is, you can form meetups on this platform. So this is one that was just posted recently. This is a volunteering meetup to help paint, I think it's a school, yes, a school, run by Elle in New York. So they're using this to help their local community. Our community is helping its local community. And here's the other great thing about decentralized and self-organized communities is that they are massive innovators. This is Maria. She started this because she basically wants to start a peer-to-peer lending platform. We didn't do this. She did this. She's amazing. So she wants to take some of the money she's earned and lend it at really, really below bank rate levels to help people buy that lampshade or that bed and start hosting, which is just awesome, I think. The other interesting way that self-organization happens is, and this is something I really, really love, is that basically what we're seeing here is this new model of decentralized power. It's a decentralized power model. And people are using their communities now to take political action. This is Peter Kwan's group. It has 821 members. Home Shows of San Francisco. It's a nonprofit community group basically totally focused on passing fair laws and figuring out the taxes. And, for example, it's funny that David was just here. He's organizing on May 14th. A review of David Chu's proposed legislation, which is awesome. He's got loads of people showing up here, as you can see. The other thing that's happening, which is also fantastic, and this is happening in Barcelona and New York and other cities around the world on the platform, is that people are self-organizing into local neighborhood groups. And so this is a local neighborhood group. I'm not sure where this one is, but it met just a few weeks ago, or a few days ago, actually. And then, because this organization is being created, when necessary and when they feel under threat, they can take overt political action. So a couple of weeks ago, maybe some of you were there, outside City Hall, when some politicians wanted to propose a ballot initiative that would have seriously threatened our hosts, business and guests staying in the city. So I'm just showing you a couple of pictures here. It was very well done. There was about 150, 200 people in attendance. People gave speeches. They had great posters like Make It Fair to Share. That's Peter Kwon giving interviews to the press. These are some of my favorite posters. Let It Be, Airbnb. This one I love here. Home Sharing. I host you, babe. It's South San Francisco. I love it. So anyway, I just wanted to share with you some of these few examples, because to me it's gratifying to see that in this peer-to-peer sharing economy, which is totally about decentralization and self-organization, people are also self-organizing in ways to help themselves, including taking political action where necessary. So thank you very much for your time.


I've been really lucky to find some awesome allies on this journey. There is, I think there really is like a genuine global movement of people trying to make a change here who are sort of putting their energy in the right direction and happy to support people. And don't be afraid to lean into that and to see that people want to help each other out. They want to advise, they want to support. And that is incredibly energizing. Humans desire to help each other out on a positive mission. So that's been amazing, actually.


My power is to walk away. God doesn't anoint me to fight God anoints me to run And see God anoints me to fight the devil, but God anoints me to run from the world See Joseph when he when the potter for his wife was tempting Joseph and she started to flirt with him in the Bible So she did it continuously Joseph did not go out to her say hey woman. Can I pray for you right now?  I pray for me Why I'm fighting with lust and I said that is your problem. He said what do you mean you're fighting with lust? I said no one in the Bible. God says to fight with lust. God says run from lust I said why are you fighting something God called you to run from? Lust you can't beat lust. That's why God says run you can beat the devil That's why God says fight him but lust is temptations.  You'll do just fine in the next few months When you keep slipping into the stuff on snapchat, well if you turn off your snapchat You will find out your high blood pressure will be just fine If you will not have that social media you will be just fine But the Bible says it's better to go into heaven with one leg instead of you know going into hell Living in hell with your Facebook snapchat Instagram Twitter and every other social media, but having no peace run from temptations and Well, how do we come how do we overcome the devil is we actually have to fight the demons We have to fight you don't overcome the devil by running from the devil see temptations you run from them the devil You cannot run from the devil Devil has to run from you Listen if you run from sin You will have no fear to run from the devil you will look at the devil and you will not be afraid of him Why because you've been running from sin and now you have no fear of the devil I remember when I was a a lot younger person and the first time that I had to face Demons alone in my car is when we were praying for one person and I think it was Thursday night He was manifesting manifesting demons were manifesting through him was a bigger guy and We prayed for him. He got free, but he didn't get free completely. That means there were some demons left And so I had to drive him back home There was only one problem He lived about 25 minutes from here into like parts of Pasco over there off of road 68 where you go in there Is no more lights there. There's no reception there and it's dark So here is like 19. I'm about think it's about 19 years of age or 19 to 20 years of age and driving my dad's Toyota Corolla this guy is twice my size Demons all the demons didn't leave He's driving we're driving there and as we are driving closer to his house. He begins to kill himself right there in my car He begins to choke himself So there I am I'm already scared The guy's killing himself and I'm like, how am I gonna explain in my mind?  How am I gonna explain to his parents that I didn't do it? I mean imagine a Russian guy brings your child. He's like really I'm a youth pastor Oh, that's what all the MS says in MS 13 says they're all youth passes really I mean, how am I gonna explain I'm sitting there and I'm like and there is no reception I can't call police. I can't call my pastor the guy and the demon took over and he begins to take I think he took a pencil something and he's trying to choke himself and trying to stab himself and there I am literally faced with the devil in the car and no one to call and I had to do what I was told to do With one hand hold the wheel with another hand hold him hold his hand his hands were twice as powerful as mine and Literally, it wasn't the power of my hands, but it was the power of the word. I couldn't run from him. I Couldn't fight him And I remember put my hand over his hands and I started to command the spirit of death.  I'm not exaggerating one part of the story We would pray here in the morning, and I don't see him for like 30 seconds I run up and I see behind the view under the view he starts to kill himself Because the demon would come on and try to kill him and right there nobody here and by myself a guy twice my size I had to learn that that day no matter how big that person is No matter how fierce the demon is and no matter how skinny I am Small I am inexperienced.   I am when you stop paying rent then move the chair move your own chair I'm not making this up That's exactly what you have to tell the devil if he wants to move the chair He can go to hell and move all the chairs he wants to but this is your apartment This is your house, and he has no right to be there Come on somebody Amen So I want to challenge each one of you young person do not simply say well, I am not a priest I am not a pastor. I don't have this and everything listen Do that doesn't matter the Holy Spirit is in you and the Holy Spirit will use you if David could do it as a Teenager you're 20 years old you're 25 years old you 15 years of age that is enough You have to overcome the devil the Bible says stand your ground.   I was overweight and I had a lot of insecurities So I tended to do whatever my friends did it wasn't until I was 13 that I Started even considering the thought of God my sister She had just recently got saved at the time and all she could ever talk about was Jesus Jesus Jesus And it annoyed me so much I couldn't couldn't stand being around her none of the family could stand to be around her and she was always seen as the Outcast in the family. She was always inviting me to church, but I never I never decided to go then one one day I remember I remember clearly going to a rock concert with one of my one of my friends And I remember during that time I ended up having a panic attack and when you're 13 years old and you have a panic attack And you don't know what's happening. You feel like you're gonna die And I remember I had to be pulled out of the mosh pit and when I was brought to the to the edge of the stadium The ambulance they came in they they checked out my vitals and ended up saying that everything was fine with me That I just needed to rest but in that moment I remember feeling like I was gonna die and I remember the thought running through my mind that if I were to die today that I didn't know Jesus Christ and That I would end up going to hell and not heaven that scared me that reality hit me at that moment And it scared me so bad to the point where I said to God God if you let me live this day I will serve you with all my life I ended up coming down from that panic attack and everything was fine and life went on It wasn't until a couple months later my sister invited me again to go to church But this time it was a encounter retreat where they went away to the mountains and I remember she asked me and I said No at first and then it seemed like out of nowhere this thought came to my mind and and I felt like it was God at that time I didn't know it was God But I was reminded of that promise that I made to God that I would follow him with all of my life I remember sitting at my friend's house. There was only an hour left till they would leave to go to the trip I called my sister up. I said wait for me I'm gonna pack my bags and I'm going and the very first night worship began and I didn't know what anything was. I just I just knew that people were singing songs I knew that something in my heart needed a change and I remember during worship This piece Coming over me so strong so so powerful that I that I couldn't Resist but to sing along with the songs to engage myself to the point where I was worshiping God And I hadn't even given my life to him yet decided to give my life to Christ since then my life has never been the same I've been on a journey of growth and freedom Particularly in the area of my purity at the age of nine I was introduced to pornography with my friend and from the time that I was nine to the time that I was about 17 I believe I struggled severely with this addiction to pornography and masturbation and It controlled my life day-to-day. I tried to keep it hidden. I tried to not let anybody know about it I was ashamed. I was embarrassed. How could somebody in the church who's been in the church for so long Have this issue It wasn't until I was 17 that I got fed up to the point where I didn't care about who knew what I had About the skeletons in my closet. I decided that I wanted to live free I wanted to live a life with God Unpurity and holiness and my desire for holiness my desire to follow after God was more than my desire to live in this sin I remember going to Africa receiving prayer through a prayer line similar to the one that we have here at hungry generation And I was delivered mightily during that time from this spirit of pornography and masturbation the spirit of lust And what used to control my life what I used to not be able to say no to what used to day in and day out Have control over my thoughts my emotions my my body and my my actions everything I did No longer had the grip that it had on my heart when ten tations came away. I was able to say no I was able to turn from them. I was no longer being hindered I was nowhere longer had this wall over my mind and over my thoughts When trying to pray but it seemed like this veil had been lifted from my heart This heaviness had been lifted from my heart And I could serve God to the fullest and to the max and now I find myself here in the church I've been going to hunger generation faithfully for almost nine years And I serve as a worship leader and I'm a home group leader I love what I do. I love helping people and I just want to give God Everything that I have I want to be able to serve him in the ways that I know how My name is Bryson still and this is my testimony


Hello, and welcome back to Fill 320, Deductive Logic. I'm Professor Matthew Brown, and today we're starting Unit 5. We'll be talking about Quantified Logic, or QL, and we're gonna talk about the basics of QL in this lecture and how we use it to symbolize and translate certain English statements into this new system. So let's start by talking about QL, what it is and why we need it. So there are certain logical structures in our language, structures including quantities like all, every, some, and none that are not captured by SL. There are also relations between objects and predicates, objects and properties or objects in relation to other objects that are not captured in a sentential level logic, which is why some accounts or some texts called this system predicate logic, right? And in yet other books and other discussions, it's called first order logic. And historically, it's a very important logical system. Here's an example of arguments that cannot be captured as well by SL as by QL. So this is perhaps a familiar one, Socrates is a man, all men are mortal, therefore Socrates is mortal. Seems like a valid argument, that is, if the premises are true, it seems like the conclusion must be true. But there are no logical connectives in any of the sentences, no if, then, no and, or none of those kinds of connectives that we used in SL. So these will be represented as atomic sentences of SL. Here's another example with the same issue, right? No person is an island, every person is mortal. So some persons are not islands. That may not be a great argument, but there's still structures, no, every, some here that are not captured by SL. So let's talk about the features of QL and its components in order to start to understand what QL does for us. Now, I should say from the get-go, everything that's part of SL, all of those connectives are also part of QL. The conjunction, disjunction, conditional negation, they're all already part of QL. Here are the other parts of QL, right? They're singular terms or what we call constants that we represent with the lower case letters, A through W, optionally with subscripts, right? So you could have them with or without subscripts. Singular terms refer to what we might call proper names in English, Socrates, Beyonce, the Eiffel Tower, Carbondale, these are all, we're gonna represent all of these sorts of proper names with constants, right? Lower case letters. And then we have variables. These are the lower case letters X, Y and Z with or without subscripts. They don't stand for specific things with proper names, but for unknown objects. We also have predicates, what we call predicates. These are capital letters, A through Z, with again, or without subscripts. These are properties or relations, right? They go before some number of singular terms or variables. Then we have the quantifiers, we have two in QL, right? One is the universal quantifier, which we represent with an upside down A. It means for all and the existential qualifier, which we represent with a backwards E, which stands for their exists. So let's look at some basic examples. If we have for all X, PX, that means that for all X, X is P or for everything that we're quantifying over, it is P, P is true of it. There exists an X, PX means that there exists an X, such that X is P. We also have this kind of, we have this exchange, right? This equivalency between the two quantifiers, right? For all X, A, where A is some arbitrary sentence is equivalent to, there does not exist an X that is not A. And also, it is not the case that for all X, A, means there is some X, such that not A. Another important feature of QL is that we have to specify a universe of discourse whenever we are making translations to and from English. That means that we have to specify what kinds of objects our variables are going to quantify over, right? We might, for example, have a universe of discourse that is animals, if we're just talking about animals or living things, right? We might, it really depends on what it is we're trying to translate and we'll look at some examples. Here are some common translations in QL. These are very common kinds of things that you're going to see. Whenever we have something like all SRP, all men are mortal in our earlier example, or every SSP, or SRP, men are mortal, where it's sort of understood that there aren't exceptions, we use universal quantifier for all X. And typically when we're relating two predicates with the universal quantifier, it's gonna be a conditional. In all of these cases, it's S first then P, if S then P. Remember our old friend only, flipping things around, it does it here too. Only SRP, we're gonna translate as for all X if PX then SX. No SRP, we could do two different ways, right? One is to say that for all X, if it's S then it's not P, right? Another is to say there does not exist an X that is both S and P. Some SRP is gonna be translated by the existential quantifier, right? There exists. There is just an X that is SX and it's PX. And note that when you use the universal quantifier, you're typically doing a conditional. When you're using the existential quantifier, you're usually doing a conjunction, very common. And then finally, some SR not P, you would translate in this way, right? There exists an S such that SX and not PX. Let's look at some examples, right? So here I've got a symbolization key at the top. First thing we start off with in our symbolization key is the universe of discourse. That's what our variables and quantifiers are going to quantify over. Then we have a number of predicates, right? AX stands for X as an organism, DX stands for X as a dog, CX for X as a cat, and FX for X as four legs. And so take a second to think about how would you translate these three sentences into English? You can pause the video if you need to. So here's the way that I would translate these. For all X, AX, I would translate as all animals are organisms. Now note, animal is not one of our predicates, but it is embedded in our universe of discourse, right? For all X in this case means for all animals, right? And so this sentence naturally translates as all animals are organisms. For all X, if DX then FX, I would translate as all dogs have four legs. D is dog, F is has four legs. So this translates to all dogs have four legs. And then this last sentence, there exists an X, CX and not FX, right? I would translate this as some cats don't have four legs, right? There are some X, right? Such that it is a cat and it does not have four legs. We don't know how many, but there are some. That's one example. Here is another series of examples. I'd like you to pause the video and try to come up with how you would translate these from English into QL. All right, let's see how you did. Zazzles is not a cat. So Zazzles is a proper name. We're gonna use a lowercase letter Z to represent Zazzles and we'll use a capital C for the predicate cat. X is a cat, right? Zazzles is not a cat. I would translate this way, not CZ. The predicate cat, capital C is applied to Zazzles, lowercase Z, and then it's the negation of that. It's not the case that Zazzles is a cat. Okay, number two, there are no new predicates. Just telling us something is a cat. I would use the existential quantifier here. There exists an X, CX. And likewise, something is not a cat. I would say there exists an X such that not CX. You might be tempted to put the negation in the front of the quantifier, not exists X, CX, but I think that's not right because that would say it is not the case that something is a cat, right? Or effectively nothing is a cat. If there's something that isn't a cat, it's best to say there exists an X such that not CX. It is not the case that something isn't a cat. We would translate it this way. It does not exist X such that not CX. You could also, this is equivalent to saying everything is a cat, right? Which would just be for all X, CX. So four and five are actually equivalent, right? Logically equivalent to each other. And we saw already why that is based on based on the equivalencies, the logical equivalencies we talked about earlier. If Ralph is a dog, then he is an animal. We gotta introduce some new symbols here for our symbol key. We'll use lower case R for the proper name Ralph. We'll use uppercase D for the predicate dog. And we'll use uppercase A for the predicate animal, right? And then I would translate this to if DR then AR, right? If Ralph is a dog, then Ralph is an animal. And then all dogs are animals, similar structure, right? But we're using the universal quantifier and a variable in this case. So I hope you did well on those. Let me know if you have any questions. I wanna take a moment to talk about how we pick a universe of discourse. In our last set of examples, we might be tempted to say that our universe of discourse is animals like the earlier examples. But that won't work, I think, because of the way that we're using animals as a predicate, right? It would be hard to represent six without that predicate A, right? So we might instead say living things. That would be a pretty simple universe of discourse, but specific enough. Everything would be too broad. Sometimes you're gonna be sort of struggling to make a choice when you have to specify a universe of discourse. Am I gonna go with a broader and simpler specification? Or am I gonna go more specific? So I might say living things, or I might say animals and plants, right? Those are different universes of discourse. It's problematic to use everything because it's not clear what everything applies to. And you can get into some paradoxical situations that way. Okay, I wanna spend a moment thinking about how we use the concept of a singular term, right? I want us to think about whether these English language phrases could be symbolized just with a constant, with a lowercase letter A through W or not. Take a second and see if you can figure out all of 12 of these. All right, let's see how you did. So number one, Bob Barker, that's a proper name. It could totally be a singular term, very reasonable. Some Bs, right? That's more generic. That's not a proper name. That's just some number of Bs. We would not use a singular term for that. Those Bs is a little trickier. You might wanna use a singular term for this or you might use a combination of the predicates, Bs and over there, something like that. I would say probably the best choice is to say no, not a singular term. It's a little debatable. My dog, Feynman, on the other hand, that's a specific object or specific creature, that's a proper name. Singular term is there. Numbers is also a category and so it would not be a singular term. The person with the highest grade in this class, would we use a singular term to refer to that? That is even more debatable. If we are sure that there is a unique person who answers that description, we could use a singular term to refer to them. If we know for a fact that there is one person with the highest grade in this class, but it might be better to try to represent it in a different way. We'll talk in the third lecture in this unit about the better way to represent that. Walter White, again, a singular term would be best here for Walter White. Even though Walter White is a fictional person, we might have our universe of discourse be fictional people or people in the show breaking bad and we'd wanna use a singular term in that case. A herd of elephants, not a singular term, nor is a herd of Asian elephants. Even though it's more specific, it's still a category. Our textbook, it's a little debatable. If I said instead of our textbook, I said for all X by P.D. Magnus, that would be a proper name for our textbook, but our textbook seems more like a predicate to me. The chimera. Now, if our universe of discourse was fictional creatures, we might say the chimera is a singular term. It refers to a specific mythical creature, not a type of mythical creature, but a specific one, the chimera. But if our universe of discourse is living creatures generally, and we don't know whether chimeras are living creatures, whether there is a chimera, that would be problematic. If the chimera doesn't exist in our universe of discourse, we couldn't use a constant to refer to it. So that's debatable, that's questionable. Same deal with today. Today names a specific day, but when I use it tomorrow, it names a different day. It's an indexical. And there's some debate about whether we should use singular terms to represent indexicals. If on the other hand, I said March 17th, 2024, that we would represent with a singular term if our universe of discourse was times, right? Or dates. Another important thing to think about in QL is the scope of the quantifier. That's what we call the part of the expression that the quantifier applies to. Or as we say sometimes, that the quantifier quantifies over, it quantifies over a certain part of the expression. That's its scope, right? So take a look at these expressions and see if you can figure out what the scope of the quantifier is. Let's see how you did. So in the first sentence, our quantifier is for all x and its scope is the whole rest of the expression, the fx, the thing it is next to. In number two, our quantifier is the same for all x and its scope is actually only this part that it is right next to. It is right next to the fx. The conditional here breaks the scope of the quantifier and so it is not within the scope. That means that the gx is, in fact, the x in gx is a free variable. We'll talk about what that means in a future lecture. In number three here, for all x is our quantifier and now that we have the parentheses right next to it, the quantifier applies to everything within those parentheses. So the scope is this larger part of the expression, the rest of the expression really. Now four is a little more complicated because we've got multiple quantifiers here. We have this existential quantifier, its scope is just the expression it's next to, fx, and we have the second quantifier, this is the second existential quantifier, it's next to a parentheses. So its scope is everything inside the parentheses. Okay, number five, we have this existential quantifier here. It is next to the parentheses and so it applies to everything inside the parentheses. Now embedded in this expression in the scope of this first quantifier, we have a second quantifier with a scope just on the atomic expression it is next to. And then here with six, it's a similar situation. We've got the existential quantifier here, applies to everything within the parentheses that are next to it. We've got this second quantifier here, also next to parentheses. So it applies to this whole expression here. And then we have the third quantifier, it only applies to what's next to it, which is just the gz. All right, so that's the basics of QL and how we use it to do translations and some of the things we have to think about when we're analyzing expressions in QL. Please have a look at some of the early practice problems and see if you can do some of the translations. And then I'll see you in the second lecture where we talk about how well-formed formulae work in QL. All right, bye.


My name is George Heimpel, and I'm going to be talking about the same system that Anthony just did, so it's great to follow that because I don't need to explain a lot of this. But I'll be working more on the natural enemies, the bio-control side of things. And I'm just sort of starting the second year of this SAIR grant. So I'll be giving a more sort of general presentation about the kind of work that the SAIR grant kind of fits into, but the SAIR from the first year will be there. So just as Anthony said, this is just a brief intro to soybean aphid. The soybean aphid is native to Asia, and it was first discovered in Wisconsin in the year 2000. And so this shows sort of the part of the country that it was in during just that first year. And it's now, as you know, spread through much of the soybean growing areas. And as Anthony mentioned, it's now sort of the primary, the key pest in soybean. An interesting thing is that, so this is showing the millions of acres here in these black bars or pounds sprayed within the north-central states. So this is basically a phrase for soybean aphid. Prior to the arrival of soybean aphid to very little spraying, once it came, you can see that this really skyrocketed. These are nasty statistics, and this is just for the years that they're there. And so we were up to almost 10 million acres sprayed. So it's clearly an important pest, oops, there's supposed to be, yeah, there we go. But it would be even a much worse pest were it not for natural enemies that are currently controlling it in the field now. So you saw that we got up to at the peak in 2006, up to spraying about 10 million acres well, that's out of 70 million. So it's not like every field is getting sprayed. And part of the reason that not every field is getting sprayed is that there are native predators of the soybean aphid that are feeding on it. And so this just shows some of these, Anthony showed a picture of a lady beetle and there are lady beetles and there are predatory flies and life swings and predatory bugs. So there are a lot of predators out there, excuse me, that are feeding on soybean aphid making it less of a critical pest than it would otherwise be. You can show this with simple cage studies where you cage some plants just as Anthony showed and you leave some field sections uncaged. And if you do for a short amount of time even, you can see that the number of aphids within the cages is much higher than in the open field. This is basically due to the action of natural enemies. This is a short enough time frame so that the cages aren't holding in the winged aphids which can happen if you do this for a long time. So biological control is real, it's happening in our fields but it's not happening to an extent to make the soybean aphid a non-pest.  So much of the focus of my work has been to ask how can we improve this? How can we improve biological control of soybean aphid so that it's a non-pest so that we don't have to spray for it? And the host plant resistance that Anthony talked about is a great way but biological control is another way and those two strategies do tend to work together well. But I'm not talking about that so I'll just focus on this stuff. So the main things that I've been working in my lab or the main strategies have been one to try to see what happens if we increase the diversity of the cropping system. And so I'll talk a little bit about that and then the other thing is that as I mentioned the soybean aphid is native to Asia and soybean aphid is a much different insect in Asia than it is here. And I've been to China a bunch of times and you know the main thing I come away with on those trips is that it's really hard to find soybean aphid. It's a rare insect there and when you find it you find soybean aphids and they're riddled with these little what we call mummies which are parasitized aphids. And what's happened to these things is that they used to be regular aphids going through their day but a parasitic wasp came up to them, stung them, laid an egg inside them and the larva then sort of fed on it from the inside. And so a lot of my work has been go to China find these parasitic wasps, see whether we can bring them here to release them. The process of doing all that means that we have to be sure that they'll be safe. So there's an incredibly long and rigorous process of safety testing that we have to go through and we've brought back about 20 species of wasps from Asia to put through this and out of those 20 we now have a permit for three. So three of those species turned out to be safe to release and so we're now working on those. And this is what one of those looks like. And so I'm going to talk about some of the work that we've been doing in these two areas. Some of that is a serowork but once we get into the main part of our serowork it's really going to be to look at an interaction. How does landscape level diversity interact with these wasps and can that give us or the best biological control? So I'll talk first about some work that we did with diversity and this actually goes back to pre-ser days and this is work that we did in organic beans and it's a fall seeded rye cover crop. And basically how this works is when you're on a corn to soybean rotation or wheat to soybean you harvest the corn or the wheat in the fall and then you plant rye into that stubble.  And I'll just kind of show you. So this is what the rye looks like in its overwintering stage. So it's sort of a shaggy lawn obviously this kind of cover crop has a lot of benefits beyond what we were looking at which is looking at the effects on soybean aphid because you're covering the soil. And this is what it looks like in the spring so it really gets up pretty high and then you actually drill into those beans, I mean into that rye, so you drill the beans into that rye and it starts to come up and that's when you mow the rye. And then you get this sort of mulchy looking field. This is one shot that we have, this is another shot that we have where we compared the rye covered beans with just you know the monoculture beans. And so I'll show you data that we got. This is a combination of on-farm studies and experiment station studies and it worked really well. So in all of these studies we had much higher, well in some cases much higher but in a lot of cases higher, but here much higher densities of aphids in the monocrop so without rye. So with the rye here we have much lower numbers. This here, I have this line supposed to be at 250, I don't know why it's there, supposed to be at 250 like ant, ant and you said that's a spray threshold. So you can see that it worked here to control soybean aphid which is great, you know the danger of course is that the rye competes with the beans to such an extent that you get a yield drag and we found that this site that this didn't happen that the yields were you know about the same. This is one site, here's another site, this is a field experiment station, not so quite pronounced, but the yield was similar. This is our favorite site, this is Lee Thomas' farm, I don't know if you guys know Lee, but he actually uses this rye sort of on a permanent basis as far as I know. And the aphids in the monoculture beans got up to about 6,000 per plant. With the rye is much lower. So the aphids here got to such high levels that there's actually a yield drag for not having the rye. So the rye actually gave a yield bump, we were worried about a yield drag but here we got a yield bump. So this is really encouraging, oh sorry, this is our last site where there were fewer aphids with the rye, but this is a case where there was a yield drag, so I don't want you to think that this thing always works perfectly and that you always get a higher yield. This is a case where there was a yield drag, so there was a higher yield in the monoculture. This was a site in the year where it was very dry and so what we think is that when it's dry, the effects of competition are stronger. So let's just think about these aphids which are lower in the presence of the rye cover crop and my whole introduction about natural enemies and bio control and how great that all is. What we thought might happen is that if we have the rye, that might give a better habitat for natural enemies so you might get better biological control. Predators eating aphids in the presence of the rye, but that wasn't the case. So at least for all the measurements that we did, we didn't find any evidence for better bio control. There are still fewer aphids but not better bio control. So what it probably is is that if you have your beans growing in this kind of a setting, the aphids simply can't find it as well and it also might be that the quality of the soybeans, the beans are lower for the aphids. So because there is some competition going on. But we think it's more sort of a plant-mediated effect than really bio control being better. So I'd like to talk about the Asian parasitoid wasps now and I'm just going to talk about two and they're both in the genus aphalinus which is a really tiny little wasp. It's called a wasp but it's nothing like a yellow jacket. So it's literally about the size of the period on a page or it's smaller than that. Like if it was walking along a page and it could walk onto a period of size 12 font and you wouldn't see it, it's that small. It's almost microscopic. So there's two species. The one is called aphalinus certus. This is not one of those that we got a permit for. This is one that came on its own. So just as soybean aphid was introduced, this one was introduced and we don't know how, we don't really know from where except that we know it's native to Asia. But it's now found here and I'll talk about that one. The other one is aphalinus iglycinus which is one that we got a permit for. So this is a safe one. This is one that really attacks only the soybean aphid. Whereas this one attacks pretty much any aphid that it comes into contact with. Oh, so yeah, this is the aphid pericid lifecycle which I already mentioned. So the wasp lays its egg inside the aphid. That egg hatches into a larva which feeds on the aphid from the inside. And then there's a pupa and it pops out once it's ready. And then the whole cycle starts again. This whole cycle takes like 12 days or so. So it's pretty quick. And each wasp can lay, you know, 200 eggs. So for aphalinus certus, the first thing I'd like to say is that we've been We first found it in Rosemount, Minnesota and St. Paul, Minnesota in 2011. And since then, this is data from this last year, so from the summer of 2014, we're partnering with the Minnesota Department of Ag to sample for it. And all these dots are sampling points. And the blue are the counties in which we found aphalinus certus. So it's pretty much throughout the state. But for the whole time that we've been sampling it, we still have never found it in the southeastern corner of the state. So we'll see. So if there's anyone here from there, I hope you don't feel too badly. But so we'll follow that. The second thing I like to show is just how it's been growing. So as I mentioned, we found it just serendipitously in August of 2011. And then in the next year, we sampled for it. And you can see in 2012, there really wasn't a lot. This is the number of wasps per plant. Sorry, this is kind of a small font. But it grew. So the highest number here is 40. So we're up to this last year, a maximum average of about 30 per plant. The maximum actual number of mummies per plant was more like a couple of 100. So if you multiply that by the number of plants, you can see that this thing has now established well. And it's a pretty major player now. It's one of the most unimportant natural enemies of soybean athid. So now I'd like to talk about Aphthalinus gliscinus. And it looks almost the same. And we got a permit for this in October of 2012. And we started to release it starting last summer and then this summer too. So 2013, where we did releases in St. Paul. And 2014, we did them at, where do we do? Again in St. Paul and also in Cottonwood and Northfield. And so this is one of our release sites. Basically what we do is that we rear them by the hundreds of thousands, which isn't that hard to do. They're very easy to rear in the lab. And we put them in these little tubs out in the middle of fields. And then we kind of monitor how far they spread. So there were these two sites that we used this last summer. And at each one, we released 75,000 wasps. And this is, by the way, the Sierra Grant. This is year one of what the Sierra Grant was about. And so this was the week of July 26 at both sites. And then you can see that at the Northfield site, we got up to, again, 30 to 40 mummies per plant in that area right around here, whereas Cottonwood less. So they were well able to establish during the field season at those sites. What we don't yet know is whether they're able to overwinter. We're pretty sure that the ones from the 2013 releases, which were done basically to study ways to release it. And we use those data to develop this method here. But we're pretty sure from all the sampling that we've done that they did not overwinter from that release. And 2013 was a very harsh winter. So we're hopeful that maybe they'll be able to overwinter now. Although this winter has had some harsh times, too. So we're now doing an overwintering study. And this is a buckthorn shrub. And some of you might not be aware, but the soybean aphid overwinter is on buckthorn. So it has this obligate movement from buckthorn in the winter to soybean in the summer and back and forth. And so this was a study. It's kind of hard to see because it's all white here. But these are buckthorn twigs that we've put mesh bags around and tied. And we had previously put wasps into those twigs that had aphids on them. So it's a way to see, will these wasps be able to overwinter here under field conditions? And so this is just from this season. So we'll know in the spring how they did. And that's sort of what I've got for you today. Just to conclude, one of my messages is that soybean aphid is a pest. But it could be a much worse pest if it weren't for the natural biological control that's happening. But we want that control to be better. And so some of the things that we're trying to do is that we're trying to increase the landscape diversity. This is a picture of some plots that we have at Rosemount where we're using prairie plots and seeing whether sort of a simulated prairie can aid biological control, which is part of this air grant that's sort of coming up. And we're also working on these parasitic wasps. And our next step really is to try to combine these. Can we use this habitat management and the wasps in a way that are synergistic, just as Anthony was saying? So I think over the next couple of years we'll be able to figure that out. And I would just like to acknowledge there's people that have worked with us on this, including farmers, Lee Thomas and Paul Aghini. And Sarah obviously helped to fund this, but there are other funding sources as well. And if there are any questions, I hope we have some time for those. Yeah. So the question was whether the height of the rye stems could have an impact. And I think it probably could. But it's not something that we really have measured or have looked at. So the question was, can we buy these wasps? Are they commercially available? And the answer is no. And it just wouldn't be economically feasible to do that. So this is a kind of project that's done at universities and at the USDA. And if it works, they'll just spread throughout the region all by themselves or with a little bit of help. And in a few years we'll all be saying, remember soybean aphid? Oh, yeah. So the question, I think, was whether or not we think that the wasps also overwinter on the buckthorn. Yes. So the answer to that is that we don't really know. But for this species, Aphthalanus gliscinus, which is a specialist, there really aren't any other aphids in Minnesota or in North America except for the cotton aphid, which is really closely related to soybean aphid. So there really aren't any other aphids that it's likely to be able to overwinter on. Pretty much has to overwinter with soybean aphid. And soybean aphid obligately overwinter on buckthorn. So I think Aphthalanus gliscinus, if it's going to be an effective biological control agent, has to find a way to get to buckthorn. And it has to be able to overwinter there. Question was, how can soybean aphid be a pest in areas that don't have the overwintering host? And the answer is that they're highly mobile little insects. They're blown. And we know that they can be blown hundreds of miles. It's probably more like thousands of miles. Yeah, yeah. So the question is with these highly mobile pests, whether the natural enemies go with them. And actually, let me go back, because there's a picture I love here. So I'm showing these mummies, right? Here's two regular looking aphids that turned into mummies. But this one, you can see that it has wings. So what does that mean? That means that a wasp stung that aphid, either when it had wings, or when it was about to have wings.  It has the egg inside of it. The egg hatches after a couple of days. And meanwhile, that aphid is living. It's feeding. In some cases, it's even reproducing. And it can fly. So what that means is that the wasps can basically hitchhike on their hosts. They can be carried within the aphids as eggs. And that's what I think is sort of the primary mechanism by which they could follow the aphids to the overwintering host and be closely linked in to the population dynamics of the aphids. So the question was whether there's as much known about the distribution of aphelina certis in other states. And the answer is not really. So aphelina certis was actually first found in Pennsylvania. And then it was found. And it's very well known in the soybean growing regions of Canada. And there, if you talk to people working in Quebec, they say aphelina certis is absolutely controlling soybean aphid. So it seems to me like it either came in on its own somehow or there was a second introduction of soybean aphid with those things more on the east coast. Because it sort of was on the east coast and it got here in 2011. But it was known from the east. But other states in between and to the west, we don't really know. I would say that soybean aphids only been here for about 15 years. So it makes sense that the natural enemy community would adapt to it. And it also makes sense that it would grow because this is an amazing new food source. And the parasitic wasps that are native to here haven't really moved on to it very much. So to me, that's sort of a mystery. I don't know why. Because there are some wasps that can feed on it. And I don't know why they're not in the fields. But these predatory insects like the lady beetles and the predatory flies and the predatory bugs have sort of upped their game over the last 10 to 15 years. So Anthony was mentioning the threshold of 250, which the research for that was done in 2004, 2005, maybe to 2006. OK, that's fine. But this is just sort of my personal opinion. I think it's too low now. And I see a lot of fields where the aphids go to 250, which is where a farmer is supposed to treat. Then they go to 400, then they go back down. And Anthony rightly said that the economic injury level, actually for $6 beans, is 675 aphids per plant. So that's why Anthony's looking at these softer insecticides. And his group with Bob Cook, that's one of the main things that they do. So definitely, you know, the Lamdisi halothrin and the Espen valerate highly toxic to all these natural enemies. But there are people looking at these softer insecticides. I'm not so up on the literature. I think a lot of times you do find what Anthony found was like, oh, this looks really promising. But you put it in the trials and it doesn't work all that well. But that's not to say that there might not be some out there that are effective.