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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 3120 | . 2 ⊢ (𝐶 ⊆ 𝐷 ↔ 𝐴 ⊆ 𝐵) |
5 | 1, 4 | mpbir 145 | 1 ⊢ 𝐶 ⊆ 𝐷 |
Colors of variables: wff set class |
Syntax hints: = wceq 1331 ⊆ wss 3066 |
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 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-11 1484 ax-4 1487 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2119 |
This theorem depends on definitions: df-bi 116 df-nf 1437 df-sb 1736 df-clab 2124 df-cleq 2130 df-clel 2133 df-in 3072 df-ss 3079 |
This theorem is referenced by: undif2ss 3433 pwsnss 3725 iinuniss 3890 brab2a 4587 rncoss 4804 imassrn 4887 rnin 4943 inimass 4950 imadiflem 5197 imainlem 5199 ssoprab2i 5853 npsspw 7272 axresscn 7661 |
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