Theorem or_comm ≪ | index | src | ≫

\or交换

theorem or_comm (A B: wff): $ A \or B \iff B \or A $;

Step	Hyp	Ref	Expression
1		neg_imp_perm	\neg A \imp B \iff \neg B \imp A
2	1	conv or	A \or B \iff B \or A

Axiom use

Logic (ax_mp, ax_1, ax_2, ax_3)