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Mirrors > Home > ILE Home > Th. List > pm4.25 | GIF version |
Description: Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 3-Jan-2005.) |
Ref | Expression |
---|---|
pm4.25 | ⊢ (𝜑 ↔ (𝜑 ∨ 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oridm 674 | . 2 ⊢ ((𝜑 ∨ 𝜑) ↔ 𝜑) | |
2 | 1 | bicomi 123 | 1 ⊢ (𝜑 ↔ (𝜑 ∨ 𝜑)) |
Colors of variables: wff set class |
Syntax hints: ↔ wb 98 ∨ wo 629 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-io 630 |
This theorem depends on definitions: df-bi 110 |
This theorem is referenced by: (None) |
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