 This comes in part from the fact that the grammatical structure of natural language sentences may conceal the logical structure.Moreover, mathematical conventions strictly specify the range of validity for formal language quantifiers; for natural language, specifying the range of validity requires dealing with non-trivial semantic problems.For example the sentence ""Someone gets mugged in New York every 10 minutes"" does not identify whether it is the same person getting mugged every 10 minutes, see also below.