Apsuvax.1010 net.games utzoo!decvax!ucbvax!ARPAVAX:mhtsa!allegra!psuvax!sibley Fri Dec 18 13:19:21 1981 Life Conway's Game of Life has a property most people are not aware of (and possibly not interested in, but here goes anyway). In the original Martin Gardner column in Scientific American it was asked whether there was a configuration which grew without limit. Later this was found to be true, namely there is a (stable) 'cannon' which shoots 'gliders'. Conway's interest in this stems from the fact that the positive answer to this question allowed him to show that Life is a universal machine, in the sense that any mathematical statement can be 'coded' into an initial Life configuration which, when allowed to run, will terminate with an empty configuration if and only if the statement is provably true. The sequence of configurations can be 'decoded' into a proof. Of course, as with most such things it is incredibly inefficient. As far as I know Conway never published the details of his proof, but they might be included in his next book. (Not his previous book 'On Numbers and Games') Conway continually invents games for the amusement of graduate students at Cambridge (the one in England) and has also devised a very useful way of doing date-to-day-of-week conversions in ones head. He calls it the Doomsday Method. Extensions to this allow him to calculate things like phases of the moon and the date of Easter in his head. I have the details of Doomsday and (somewhere, I think) phases of the moon, if anyone is interested. dave psuvax!sibley ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.