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Mirrors > Home > ILE Home > Th. List > eqssi | GIF version |
Description: Infer equality from two subclass relationships. Compare Theorem 4 of [Suppes] p. 22. (Contributed by NM, 9-Sep-1993.) |
Ref | Expression |
---|---|
eqssi.1 | ⊢ 𝐴 ⊆ 𝐵 |
eqssi.2 | ⊢ 𝐵 ⊆ 𝐴 |
Ref | Expression |
---|---|
eqssi | ⊢ 𝐴 = 𝐵 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqssi.1 | . 2 ⊢ 𝐴 ⊆ 𝐵 | |
2 | eqssi.2 | . 2 ⊢ 𝐵 ⊆ 𝐴 | |
3 | eqss 3117 | . 2 ⊢ (𝐴 = 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴)) | |
4 | 1, 2, 3 | mpbir2an 927 | 1 ⊢ 𝐴 = 𝐵 |
Colors of variables: wff set class |
Syntax hints: = wceq 1332 ⊆ wss 3076 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-5 1424 ax-7 1425 ax-gen 1426 ax-ie1 1470 ax-ie2 1471 ax-8 1483 ax-11 1485 ax-4 1488 ax-17 1507 ax-i9 1511 ax-ial 1515 ax-i5r 1516 ax-ext 2122 |
This theorem depends on definitions: df-bi 116 df-nf 1438 df-sb 1737 df-clab 2127 df-cleq 2133 df-clel 2136 df-in 3082 df-ss 3089 |
This theorem is referenced by: inv1 3404 unv 3405 undifabs 3444 intab 3808 intid 4154 find 4521 limom 4535 dmv 4763 0ima 4907 rnxpid 4981 dftpos4 6168 axaddf 7700 axmulf 7701 dfuzi 9185 unirnioo 9786 txuni2 12464 dvef 12896 reeff1o 12902 |
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