Theorem or_eliml ≪ | index | src | ≫

\or左消除

theorem or_eliml (A B: wff): $ A \or B \imp \neg A \imp B $;

Step	Hyp	Ref	Expression
1		imp_refl	(\neg A \imp B) \imp \neg A \imp B
2	1	conv or	A \or B \imp \neg A \imp B

Axiom use

Logic (ax_mp, ax_1, ax_2)