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Mirrors > Home > MPE Home > Th. List > Mathboxes > tsbi2 | Structured version Visualization version GIF version |
Description: A Tseitin axiom for logical biimplication, in deduction form. (Contributed by Giovanni Mascellani, 24-Mar-2018.) |
Ref | Expression |
---|---|
tsbi2 | ⊢ (𝜃 → ((𝜑 ∨ 𝜓) ∨ (𝜑 ↔ 𝜓))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm5.21 903 | . . . 4 ⊢ ((¬ 𝜑 ∧ ¬ 𝜓) → (𝜑 ↔ 𝜓)) | |
2 | 1 | olcd 408 | . . 3 ⊢ ((¬ 𝜑 ∧ ¬ 𝜓) → ((𝜑 ∨ 𝜓) ∨ (𝜑 ↔ 𝜓))) |
3 | pm4.57 518 | . . . . 5 ⊢ (¬ (¬ 𝜑 ∧ ¬ 𝜓) ↔ (𝜑 ∨ 𝜓)) | |
4 | 3 | biimpi 206 | . . . 4 ⊢ (¬ (¬ 𝜑 ∧ ¬ 𝜓) → (𝜑 ∨ 𝜓)) |
5 | 4 | orcd 407 | . . 3 ⊢ (¬ (¬ 𝜑 ∧ ¬ 𝜓) → ((𝜑 ∨ 𝜓) ∨ (𝜑 ↔ 𝜓))) |
6 | 2, 5 | pm2.61i 176 | . 2 ⊢ ((𝜑 ∨ 𝜓) ∨ (𝜑 ↔ 𝜓)) |
7 | 6 | a1i 11 | 1 ⊢ (𝜃 → ((𝜑 ∨ 𝜓) ∨ (𝜑 ↔ 𝜓))) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 196 ∨ wo 383 ∧ wa 384 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 |
This theorem is referenced by: tsxo2 33945 mpt2bi123f 33971 mptbi12f 33975 ac6s6 33980 |
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