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Mirrors > Home > MPE Home > Th. List > dfss2 | Structured version Visualization version GIF version |
Description: Alternate definition of the subclass relationship between two classes. Definition 5.9 of [TakeutiZaring] p. 17. (Contributed by NM, 8-Jan-2002.) Avoid ax-10 2138, ax-11 2155, ax-12 2172. (Revised by SN, 16-May-2024.) |
Ref | Expression |
---|---|
dfss2 | ⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfcleq 2726 | . 2 ⊢ (𝐴 = (𝐴 ∩ 𝐵) ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∩ 𝐵))) | |
2 | dfss 3967 | . 2 ⊢ (𝐴 ⊆ 𝐵 ↔ 𝐴 = (𝐴 ∩ 𝐵)) | |
3 | pm4.71 559 | . . . 4 ⊢ ((𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ↔ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵))) | |
4 | elin 3965 | . . . . 5 ⊢ (𝑥 ∈ (𝐴 ∩ 𝐵) ↔ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵)) | |
5 | 4 | bibi2i 338 | . . . 4 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∩ 𝐵)) ↔ (𝑥 ∈ 𝐴 ↔ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵))) |
6 | 3, 5 | bitr4i 278 | . . 3 ⊢ ((𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∩ 𝐵))) |
7 | 6 | albii 1822 | . 2 ⊢ (∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵) ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ (𝐴 ∩ 𝐵))) |
8 | 1, 2, 7 | 3bitr4i 303 | 1 ⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 397 ∀wal 1540 = wceq 1542 ∈ wcel 2107 ∩ cin 3948 ⊆ wss 3949 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1914 ax-6 1972 ax-7 2012 ax-8 2109 ax-9 2117 ax-ext 2704 |
This theorem depends on definitions: df-bi 206 df-an 398 df-tru 1545 df-ex 1783 df-sb 2069 df-clab 2711 df-cleq 2725 df-clel 2811 df-v 3477 df-in 3956 df-ss 3966 |
This theorem is referenced by: dfss3 3971 dfss6 3972 dfss2f 3973 ssel 3976 sselOLD 3977 ssriv 3987 ssrdv 3989 sstr2 3990 eqss 3998 nss 4047 rabss2 4076 ssconb 4138 ssequn1 4181 unss 4185 ssin 4231 ssdif0 4364 difin0ss 4369 inssdif0 4370 reldisj 4452 reldisjOLD 4453 ssundif 4488 sbcssg 4524 pwss 4626 snssb 4787 snssgOLD 4789 pwpw0 4817 pwsnOLD 4902 ssuni 4937 unissb 4944 unissbOLD 4945 iunssf 5048 iunss 5049 dftr2 5268 axpweq 5349 axpow2 5366 ssextss 5454 ssrel 5783 ssrelOLD 5784 ssrel2 5786 ssrelrel 5797 reliun 5817 relop 5851 idrefALT 6113 funimass4 6957 dfom2 7857 inf2 9618 grothprim 10829 psslinpr 11026 ltaddpr 11029 isprm2 16619 vdwmc2 16912 acsmapd 18507 ismhp3 21686 dfconn2 22923 iskgen3 23053 metcld 24823 metcld2 24824 isch2 30476 pjnormssi 31421 ssiun3 31790 ssrelf 31844 bnj1361 33839 bnj978 33960 fineqvpow 34096 dffr5 34724 brsset 34861 sscoid 34885 relowlpssretop 36245 fvineqsneq 36293 unielss 41967 rp-fakeinunass 42266 rababg 42325 dfhe3 42526 snhesn 42537 dffrege76 42690 ntrneiiso 42842 ntrneik2 42843 ntrneix2 42844 ntrneikb 42845 expanduniss 43052 ismnuprim 43053 ismnushort 43060 onfrALTlem2 43307 trsspwALT 43579 trsspwALT2 43580 snssiALTVD 43588 snssiALT 43589 sstrALT2VD 43595 sstrALT2 43596 sbcssgVD 43644 onfrALTlem2VD 43650 sspwimp 43679 sspwimpVD 43680 sspwimpcf 43681 sspwimpcfVD 43682 sspwimpALT 43686 unisnALT 43687 icccncfext 44603 |
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