The Secret Garden of Rock-Paper-Scissors (opens in new tab)

Paging sdenton4.

Once when I was in grad school I noticed an announcement for a lighthearted programming competition for rock-paper-scissors playing agent. The deadline was barely hours away and I was behind on a report for funding or course work, I can't recall now.

As it always happens with me, a non-serious non-essential task suddenly looks attractive over some work I had been procrastinating on.

With no time available to code up a submission from scratch i I just rigged up the zlib compression library to decide the next play. It considered appending the 3 potential completions of the play so far and compressed the sequence. Whichever appended symbol gave the maximum compression was my agent's next move.

It was just a few lines of code and it did surprisingly well. A universal compression library/algorithm that works better for short strings would have performed better. Zlib is an universal compressor but does not converge to the entropy of a sequence very fast.

The only secret strategy I know only works against my good friends son who literally starts every new round of rock scissors paper with scissors. Play him 10 minutes later he starts with scissors.

We we noticed this so we began to say let's play a round and throw paper and lose. 5 minutes later repeat and lose again. THEN, once our drink was almost finished we would say come on one more game and if I win you have to go get me a can from the fridge. He would agree and we would this time throw rock beating him and winning. It works every single time. Lol

The only real game is Rock-Paper-Scissors-Lizard-Spock

I wonder how OP calculated the Nash equilibrium for each of those game variants.