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Mirrors > Home > ILE Home > Th. List > equcomi | GIF version |
Description: Commutative law for equality. Lemma 7 of [Tarski] p. 69. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
equcomi | ⊢ (𝑥 = 𝑦 → 𝑦 = 𝑥) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | equid 1677 | . 2 ⊢ 𝑥 = 𝑥 | |
2 | ax-8 1482 | . 2 ⊢ (𝑥 = 𝑦 → (𝑥 = 𝑥 → 𝑦 = 𝑥)) | |
3 | 1, 2 | mpi 15 | 1 ⊢ (𝑥 = 𝑦 → 𝑦 = 𝑥) |
Colors of variables: wff set class |
Syntax hints: → wi 4 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-gen 1425 ax-ie2 1470 ax-8 1482 ax-17 1506 ax-i9 1510 |
This theorem depends on definitions: df-bi 116 |
This theorem is referenced by: ax6evr 1681 equcom 1682 equcoms 1684 ax10 1695 cbv2h 1724 equvini 1731 equveli 1732 equsb2 1759 drex1 1770 sbcof2 1782 aev 1784 cbvexdh 1898 rext 4137 iotaval 5099 prodmodc 11347 |
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