Description: Dual of truan (which has biconditional reversed). (Contributed by BJ, 26-Oct-2019) (Proof modification is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | bj-falor | ⊢ ( 𝜑 ↔ ( ⊥ ∨ 𝜑 ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fal | ⊢ ¬ ⊥ | |
2 | 1 | bj-biorfi | ⊢ ( 𝜑 ↔ ( ⊥ ∨ 𝜑 ) ) |