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Mirrors > Home > MPE Home > Th. List > nelneq2 | Structured version Visualization version GIF version |
Description: A way of showing two classes are not equal. (Contributed by NM, 12-Jan-2002.) |
Ref | Expression |
---|---|
nelneq2 | ⊢ ((𝐴 ∈ 𝐵 ∧ ¬ 𝐴 ∈ 𝐶) → ¬ 𝐵 = 𝐶) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eleq2 2899 | . . 3 ⊢ (𝐵 = 𝐶 → (𝐴 ∈ 𝐵 ↔ 𝐴 ∈ 𝐶)) | |
2 | 1 | biimpcd 251 | . 2 ⊢ (𝐴 ∈ 𝐵 → (𝐵 = 𝐶 → 𝐴 ∈ 𝐶)) |
3 | 2 | con3dimp 411 | 1 ⊢ ((𝐴 ∈ 𝐵 ∧ ¬ 𝐴 ∈ 𝐶) → ¬ 𝐵 = 𝐶) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 398 = wceq 1531 ∈ wcel 2108 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1905 ax-6 1964 ax-7 2009 ax-8 2110 ax-9 2118 ax-ext 2791 |
This theorem depends on definitions: df-bi 209 df-an 399 df-ex 1775 df-cleq 2812 df-clel 2891 |
This theorem is referenced by: nelne1 3111 ssnelpss 4086 opthwiener 5395 ssfin4 9724 pwxpndom2 10079 fzneuz 12980 hauspwpwf1 22587 topdifinffinlem 34620 clsk1indlem1 40386 |
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