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Mirrors > Home > ILE Home > Th. List > 3sstr4i | GIF version |
Description: Substitution of equality in both sides of a subclass relationship. (Contributed by NM, 13-Jan-1996.) (Proof shortened by Eric Schmidt, 26-Jan-2007.) |
Ref | Expression |
---|---|
3sstr4.1 | ⊢ 𝐴 ⊆ 𝐵 |
3sstr4.2 | ⊢ 𝐶 = 𝐴 |
3sstr4.3 | ⊢ 𝐷 = 𝐵 |
Ref | Expression |
---|---|
3sstr4i | ⊢ 𝐶 ⊆ 𝐷 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 3sstr4.1 | . 2 ⊢ 𝐴 ⊆ 𝐵 | |
2 | 3sstr4.2 | . . 3 ⊢ 𝐶 = 𝐴 | |
3 | 3sstr4.3 | . . 3 ⊢ 𝐷 = 𝐵 | |
4 | 2, 3 | sseq12i 3198 | . 2 ⊢ (𝐶 ⊆ 𝐷 ↔ 𝐴 ⊆ 𝐵) |
5 | 1, 4 | mpbir 146 | 1 ⊢ 𝐶 ⊆ 𝐷 |
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: undif2ss 3513 pwsnss 3818 iinuniss 3984 brab2a 4697 rncoss 4915 imassrn 4999 rnin 5056 inimass 5063 imadiflem 5314 imainlem 5316 ssoprab2i 5984 npsspw 7499 axresscn 7888 |
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