Prigogine min-σ theorem: X_2^ss = -L_{12}/L_{22}·X_1 (2-flow residual ≡ 0)

Exact algebraic instance of the Prigogine theorem for two coupled linear fluxes. Entropy production σ = L_{11}X_1² + 2 L_{12} X_1 X_2 + L_{22} X_2² (Onsager-symmetric, positive-definite for stability). Stationarity w.r.t. the free force…