An even smaller period-15 glider gun!

Recently, Dietrich Leithner ( presented a much smaller pseudo-p15 glider gun that he had already constructed by the time I presented the smallest one I knew about. What else can I say? It's really really small, and elegant too. In case, your browser doesn't start an applet above, here's what it looks like:

Text of 25-Oct-95

The first glider gun ever found was the period-30 gun, which uses two "queen bee" shuttles that collide every 30 generations in a particular way to create a new glider. Since that time, glider guns of other periods have been found, or constructed from lower period components using a variety of techniques, such as colliding two output streams in a period-doubling reaction.

One can also divide the period of a glider stream in half by using a combination of guns to insert gliders into the gaps of a higher period stream. In this case, the gun itself has a strictly higher period than its output stream, which is why the term pseudo is used. Note, however, that it produces the same output stream as a proper gun of the same periodicity.

Several years ago, the first pseudo period-15 glider gun was constructed by Dean Hickerson, using a glider turning reaction discovered by David Buckingham. Recently, this problem was revisited by David Buckingham, who constructed a smaller gun, which is included in the most recent pattern archive. The picture above shows an even smaller version of the pattern, constructed in October '95 by Dean Hickerson. A pattern file that can be run in a Life simulation program is linked to the picture.

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