for (let i = 0; i < this.Rhs.length; ++i) {
            const newGoal1 = this.Rhs[i].ApplySubstitution(substitution);
            const newGoal2 = otherClause.Rhs[i].ApplySubstitution(substitution);
            const substitution2 = newGoal1.Unify(newGoal2);