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Related theorems GIF version |
| Description: Define conjunction (logical 'and'). Definition of [Margaris] p. 49. |
| Ref | Expression |
|---|---|
| df-an | ⊢ ((φ ⋀ ψ) ↔ ¬ (φ → ¬ ψ)) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wph | . . 3 wff φ | |
| 2 | wps | . . 3 wff ψ | |
| 3 | 1, 2 | wa 223 | . 2 wff (φ ⋀ ψ) |
| 4 | 2 | wn 2 | . . . 4 wff ¬ ψ |
| 5 | 1, 4 | wi 3 | . . 3 wff (φ → ¬ ψ) |
| 6 | 5 | wn 2 | . 2 wff ¬ (φ → ¬ ψ) |
| 7 | 3, 6 | wb 146 | 1 wff ((φ ⋀ ψ) ↔ ¬ (φ → ¬ ψ)) |
| Colors of variables: wff set class |
| This definition is referenced by: pm4.63 228 iman 237 imnan 242 pm3.2 283 jca 288 anor 304 pm3.26 319 pm3.27 323 impexp 347 anass 439 bi 514 pm5.32 643 hban 1008 19.29 1070 19.35 1074 equsex 1151 sban 1236 r19.35 1757 aceq5lem4 4721 kmlem3 4750 nmcopexlem1 9907 nmcfnexlem1 9936 |