def gibbsVariance (ε x : Fin J → ℝ) (T h : ℝ) (f : Fin J → ℝ) : ℝ := gibbsMean ε x T h (fun j => f j ^ 2) - (gibbsMean ε x T h f) ^ 2
thesis/CESProofs/Dynamics/GibbsMeasure.lean:53
Gibbs Measure for Finite Discrete Systems: