Intuitionistic Logic Explorer |
< Previous
Next >
Nearby theorems |
||
Mirrors > Home > ILE Home > Th. List > eqss | GIF version |
Description: The subclass relationship is antisymmetric. Compare Theorem 4 of [Suppes] p. 22. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
eqss | ⊢ (𝐴 = 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | albiim 1463 | . 2 ⊢ (∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) ↔ (∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵) ∧ ∀𝑥(𝑥 ∈ 𝐵 → 𝑥 ∈ 𝐴))) | |
2 | dfcleq 2131 | . 2 ⊢ (𝐴 = 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) | |
3 | dfss2 3081 | . . 3 ⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) | |
4 | dfss2 3081 | . . 3 ⊢ (𝐵 ⊆ 𝐴 ↔ ∀𝑥(𝑥 ∈ 𝐵 → 𝑥 ∈ 𝐴)) | |
5 | 3, 4 | anbi12i 455 | . 2 ⊢ ((𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴) ↔ (∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵) ∧ ∀𝑥(𝑥 ∈ 𝐵 → 𝑥 ∈ 𝐴))) |
6 | 1, 2, 5 | 3bitr4i 211 | 1 ⊢ (𝐴 = 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 103 ↔ wb 104 ∀wal 1329 = wceq 1331 ∈ wcel 1480 ⊆ 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: eqssi 3108 eqssd 3109 sseq1 3115 sseq2 3116 eqimss 3146 ssrabeq 3178 uneqin 3322 ss0b 3397 vss 3405 sssnm 3676 unidif 3763 ssunieq 3764 iuneq1 3821 iuneq2 3824 iunxdif2 3856 ssext 4138 pweqb 4140 eqopab2b 4196 pwunim 4203 soeq2 4233 iunpw 4396 ordunisuc2r 4425 tfi 4491 eqrel 4623 eqrelrel 4635 coeq1 4691 coeq2 4692 cnveq 4708 dmeq 4734 relssres 4852 xp11m 4972 xpcanm 4973 xpcan2m 4974 ssrnres 4976 fnres 5234 eqfnfv3 5513 fneqeql2 5522 fconst4m 5633 f1imaeq 5669 eqoprab2b 5822 fo1stresm 6052 fo2ndresm 6053 nnacan 6401 nnmcan 6408 ixpeq2 6599 sbthlemi3 6840 isprm2 11787 bastop1 12241 epttop 12248 opnneiid 12322 cnntr 12383 metequiv 12653 bj-sseq 12988 bdeq0 13054 bdvsn 13061 bdop 13062 bdeqsuc 13068 bj-om 13124 |
Copyright terms: Public domain | W3C validator |