Reference · The Applied Higher-Order Functions catalogue
rainbow.algorithms.proofs.ahof.nash-equilibrium
AHoF D77 Nash Equilibrium (support enumeration): a strategy profile is a Nash equilibrium when no player can gain by unilaterally deviating. The per-player stability test compares the payoff of a candidate deviation against the current payoff: no-profitable-deviation? current deviation = decide (deviation <= current). When every player's every deviation is no better than the current payoff, the profile is an equilibrium. Proved native and axiom-free: the no-deviation decision, a stable profile, the native at-most stability certificate, and a profitable deviation that breaks stability. Requires audit/decide-nnrat-at-most, nnrat/at-most, nnrat/decide-at-most-true-sound (all in the D63 checkpoint). Scope (measured by the kernel): this module has 3 worked instances (statements about specific values). None of its theorems is a guarantee about the algorithm for all inputs; `lein verify rainbow.algorithms.proofs.ahof.nash-equilibrium` prints this classification.
nash/no-profitable-deviation?
nash/no-profitable-deviation? : (x₁ x₂ : ℚ≥0) → data/Bool
ℚ≥0 = nnrat/NonnegativeRational
nash/stable-profile
nash/stable-profile : → bo/is-safe 3/4 1/2 = data/true
= = equality/Eq
nash/stability-certificate
nash/stability-certificate : → 1/2 ≤ 3/4
≤ = nnrat/at-most
nash/profitable-deviation
nash/profitable-deviation : → bo/is-safe 1/2 3/4 = data/false
= = equality/Eq