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Mirrors > Home > ILE Home > Th. List > neirr | GIF version |
Description: No class is unequal to itself. (Contributed by Stefan O'Rear, 1-Jan-2015.) (Proof rewritten by Jim Kingdon, 15-May-2018.) |
Ref | Expression |
---|---|
neirr | ⊢ ¬ 𝐴 ≠ 𝐴 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqid 2040 | . . 3 ⊢ 𝐴 = 𝐴 | |
2 | 1 | notnoti 574 | . 2 ⊢ ¬ ¬ 𝐴 = 𝐴 |
3 | df-ne 2206 | . . 3 ⊢ (𝐴 ≠ 𝐴 ↔ ¬ 𝐴 = 𝐴) | |
4 | 3 | notbii 594 | . 2 ⊢ (¬ 𝐴 ≠ 𝐴 ↔ ¬ ¬ 𝐴 = 𝐴) |
5 | 2, 4 | mpbir 134 | 1 ⊢ ¬ 𝐴 ≠ 𝐴 |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 = wceq 1243 ≠ wne 2204 |
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-gen 1338 ax-ext 2022 |
This theorem depends on definitions: df-bi 110 df-cleq 2033 df-ne 2206 |
This theorem is referenced by: neldifsn 3497 0nnq 6462 1nuz2 8543 |
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