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Mirrors > Home > MPE Home > Th. List > nornot | Structured version Visualization version GIF version |
Description: ¬ is expressible via ⊽. (Contributed by Remi, 25-Oct-2023.) (Proof shortened by Wolf Lammen, 8-Dec-2023.) |
Ref | Expression |
---|---|
nornot | ⊢ (¬ 𝜑 ↔ (𝜑 ⊽ 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-nor 1523 | . . 3 ⊢ ((𝜑 ⊽ 𝜑) ↔ ¬ (𝜑 ∨ 𝜑)) | |
2 | oridm 901 | . . 3 ⊢ ((𝜑 ∨ 𝜑) ↔ 𝜑) | |
3 | 1, 2 | xchbinx 333 | . 2 ⊢ ((𝜑 ⊽ 𝜑) ↔ ¬ 𝜑) |
4 | 3 | bicomi 223 | 1 ⊢ (¬ 𝜑 ↔ (𝜑 ⊽ 𝜑)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 205 ∨ wo 843 ⊽ wnor 1522 |
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 206 df-or 844 df-nor 1523 |
This theorem is referenced by: noran 1528 noranOLD 1529 noror 1530 nororOLD 1531 |
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