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Stream: community: general

Topic: Game semantics/game theory


view this post on Zulip (=_=) (Apr 26 2020 at 08:42):

Jalex Stark said:

I have a category of "games" and "simulations" such that the product and coproduct in this category correspond to some of the constructions in the CS literature.

What I'm curious about is how this differs from the category of "open games" that Jules Hedges defined. The most recent iteration of that is here, which Jules has characterised as generalising from lenses to optics.

view this post on Zulip Jules Hedges (Apr 26 2020 at 11:01):

It's always safe to start out assuming that something from game semantics has no relation to something from game theory. It might do, but that would be a bonus

view this post on Zulip (=_=) (Apr 27 2020 at 01:26):

Jules Hedges said:

It's always safe to start out assuming that something from game semantics has no relation to something from game theory. It might do, but that would be a bonus

Sorry, I'm confused by this statement. Could you clarify how the definition of MIP* is game-semantic but not game-theoretic in nature? Per the definitions in the Complexity Zoo:

MIP*: MIP With Quantum Provers

Same as MIP, except that the provers can share arbitrarily many entangled qubits. The verifier is classical, as are all messages between the provers and verifier.

MIP: Multi-Prover Interactive Proof

Same as IP, except that now the verifier can exchange messages with many provers, not just one. The provers cannot communicate with each other during the execution of the protocol, so the verifier can "cross-check" their assertions (as with suspects in separate interrogation rooms).

IP: Interactive Proof Systems

The class of decision problems for which a "yes" answer can be verified by an interactive proof. Here a probabilistic polynomial-time verifier sends messages back and forth with an all-powerful prover. They can have polynomially many rounds of interaction. Given the verifier's algorithm, at the end:

  1. If the answer is "yes," the prover must be able to behave in such a way that the verifier accepts with probability at least 2/3 (over the choice of the verifier's random bits).

  2. If the answer is "no," then however the prover behaves the verifier must reject with probability at least 2/3.

view this post on Zulip Jules Hedges (Apr 27 2020 at 13:43):

Yes, anything where you have 2 players and you break the symmetry between them by considering one the "verifier" and one the "falsifier" is game semantics

view this post on Zulip Jules Hedges (Apr 27 2020 at 13:44):

An example of a complexity class that is game-theoretic in nature is NASH, which contains the problem of approximating Brouwer ε\varepsilon-fixpoints

view this post on Zulip (=_=) (Apr 27 2020 at 14:08):

Seems like there's a bonus.