public GeneralizedImplicitFunction<Domain> SymmetricDifference(GeneralizedImplicitFunction<Domain> second) => new Delegated((x, ε) => Evaluate(x, ε) ^ second.Evaluate(x, ε));
public GeneralizedImplicitFunction<Domain> Except(GeneralizedImplicitFunction<Domain> second) => new Delegated((x, ε) => Evaluate(x, ε) && !second.Evaluate(x, ε));
