Tit for tat

[Seymore4Head]

On Tue, 28 Apr 2015 15:16:05 -0700 (PDT), John Ladasky
<john_ladasky at sbcglobal.net> wrote:

>On Tuesday, April 28, 2015 at 1:10:14 PM UTC-7, Robert Kern wrote:
>> On 2015-04-28 07:58, Steven D'Aprano wrote:
>
>> I do believe he is trying to make a crude joke.
>
>I agree, that's what he's doing.  And I find it ironic, since he started this thread, and seemed to invite a serious discussion of the topic.
>
I did start out serious.  I thought I was making a pretty funny joke
too.  I though both were allowed.
I guess not.  Sorry

What I was fishing for were personal stories of programmers that had
tried the tit for tat program challenge.

>I thought that Patrick Grim's analysis was very interesting, showing that the Spatialized Iterated Prisoner's Dilemma (SIPD) could emulate the Wireworld cellular automaton, which is a Turing-complete system.  Thus, the SIPD, a seemingly simple system at first glance, includes configurations which are formally undecidable in the Gödelian sense.  I'm not sure whether Grim proved that an SIPD which includes the Tit for Tat strategy could emulate Wireworld, but it seems likely that one could be built.