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Mirrors > Home > ILE Home > Th. List > pm5.11dc | GIF version |
Description: A decidable proposition or its negation implies a second proposition. Based on theorem *5.11 of [WhiteheadRussell] p. 123. (Contributed by Jim Kingdon, 29-Mar-2018.) |
Ref | Expression |
---|---|
pm5.11dc | ⊢ (DECID φ → (DECID ψ → ((φ → ψ) ∨ (¬ φ → ψ)))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dcim 783 | . 2 ⊢ (DECID φ → (DECID ψ → DECID (φ → ψ))) | |
2 | pm2.5dc 762 | . . 3 ⊢ (DECID φ → (¬ (φ → ψ) → (¬ φ → ψ))) | |
3 | pm2.54dc 789 | . . 3 ⊢ (DECID (φ → ψ) → ((¬ (φ → ψ) → (¬ φ → ψ)) → ((φ → ψ) ∨ (¬ φ → ψ)))) | |
4 | 2, 3 | syl5com 26 | . 2 ⊢ (DECID φ → (DECID (φ → ψ) → ((φ → ψ) ∨ (¬ φ → ψ)))) |
5 | 1, 4 | syld 40 | 1 ⊢ (DECID φ → (DECID ψ → ((φ → ψ) ∨ (¬ φ → ψ)))) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∨ wo 628 DECID wdc 741 |
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-in1 544 ax-in2 545 ax-io 629 |
This theorem depends on definitions: df-bi 110 df-dc 742 |
This theorem is referenced by: (None) |
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