fact: Hypothesis (EQx: sigma x = enc m) (EQy: sigma y = enc n) (EQz: sigma z = enc p).
imports: List Arith Lia Undecidability.HOU(std.std calculus.calculus) Undecidability.HOU.second_order(diophantine_equations dowek.encoding) Undecidability.HOU.unification.nth_order_unification