Sub:
명제식,propositional_formula?
원자식,atom = atomic_formula
일차식,first-order_formula ? =,first-order_formula . first-order_formula
{
first-order formula
명제식,propositional_formula?
원자식,atom = atomic_formula
일차식,first-order_formula ? =,first-order_formula . first-order_formula
{
first-order formula