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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 3185 | . 2 ⊢ (𝐴 = 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴)) | |
4 | 1, 2, 3 | mpbir2an 944 | 1 ⊢ 𝐴 = 𝐵 |
Colors of variables: wff set class |
Syntax hints: = wceq 1364 ⊆ wss 3144 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-5 1458 ax-7 1459 ax-gen 1460 ax-ie1 1504 ax-ie2 1505 ax-8 1515 ax-11 1517 ax-4 1521 ax-17 1537 ax-i9 1541 ax-ial 1545 ax-i5r 1546 ax-ext 2171 |
This theorem depends on definitions: df-bi 117 df-nf 1472 df-sb 1774 df-clab 2176 df-cleq 2182 df-clel 2185 df-in 3150 df-ss 3157 |
This theorem is referenced by: inv1 3474 unv 3475 undifabs 3514 intab 3888 intid 4242 find 4616 limom 4631 dmv 4861 0ima 5006 rnxpid 5081 dftpos4 6288 axaddf 7897 axmulf 7898 dfuzi 9393 unirnioo 10003 4sqlem19 12441 txuni2 14213 dvef 14645 reeff1o 14651 |
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