Game Theory 101 (#61): The Folk Theorem

gametheory101.com/courses/game-theory-101/
This lecture covers the folk theorem. It tells us that the set of equilibria for infinitely repeated games is HUGE. I use the infinitely repeated prisoner's dilemma throughout to give a reference point, though the logic applies to any infinitely repeated game.

[@alexgao5884]

this explanation of the folk theorem is epic

[@Gametheory101]

I feel safe in saying that this is the first time that sentence has ever been written in the history of mankind.

[@PunmasterSTP]

Folk? More like Fork, 'cause I'm eating up all the knowledge you're sharing. Thanks so much for putting all this stuff up on KZbin!

[@fatty3910]

lmao, ate, slayed, devoured

[@PunmasterSTP]

@@fatty3910Folk yeah!

[@zeppelone1]

Interesting, good and very useful course! Is it possible to provide some references in the descriptions of the videos? it will definitively complete the job.

[@kanikgupta22]

By far the best explanation of folk theorem available on yt.

[@vincenthao6736]

Does the punishment strategy have to be credible in a SPE? As in a profitable deviation exists for the punisher. Does the deviator realize that the minimax punishment imposed on him is not optimal for the punisher, therefore ignores the threat of the Grim Trigger punishment?

[@anandjacobabraham4209]

Hi William, can you provide a reference for the folk theorem covered in this video?

[@chrisp9625]

You have mentioned that Tit-for-tat is not SPE. However, there is also a possibility that Tit-for-tat can be SPNE where delta is sufficiently large, so cooperating would generates greater payoffs which follows (cooperates, cooperates) forever. I believe the strategy of tit-for-tat is the following: start cooperating and cooperates forever if the opponent cooperates. Also, start out cooperating and if the opponent defected, defect in the next round then go back to cooperation. Please correct me if I were wrong. Thank you for your time.

[@Gametheory101]

In what you described, tit-for-tat is a Nash equilibrium but not subgame perfect. The previous video explains this: kzbin.info/www/bejne/lXPFd4udh894mbc

[@collinchen2750]

What about cases where the alternative strategy is strictly less than the Nash Equilibrium but within the range of individually rational and feasible payoff vectors. How would you construct a punishment scheme in that case to enforce behavior?

[@Willmick12]

Hey William, you posted this on my birthday and I appreciate you for thinking about me. My name is also William. Small world. Godsend

[@lkentonon]

Happy Birthday William

[@zarifrasul7942]

8:59 "In order for you to not take the jump in payoff today, it must be the case that you are discounting by a lot". If your discount factor is large, shouldn't you be taking that increase in payoff today?

[@willsanderson4239]

My guy thank you

[@zes7215]

no such thing as topix or natural to ax or not, cpux, say/ can say any nmw and any be perfx

[@PunmasterSTP]

Sorry I'm not quite sure I understand; what are you trying to say?

[@fatty3910]

@@PunmasterSTP oooogaa boogaaa

[@PunmasterSTP]

@@fatty3910Indeed. You know what they were trying to say?

[@fatty3910]

@@PunmasterSTP he's saying he loves watching oily black men kissing 😔

[@PunmasterSTP]

@@fatty3910 I don’t quite understand, but I think I’ll leave it there…