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Mirrors > Home > MPE Home > Th. List > intex | Structured version Visualization version GIF version |
Description: The intersection of a nonempty class exists. Exercise 5 of [TakeutiZaring] p. 44 and its converse. (Contributed by NM, 13-Aug-2002.) |
Ref | Expression |
---|---|
intex | ⊢ (𝐴 ≠ ∅ ↔ ∩ 𝐴 ∈ V) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | n0 4347 | . . 3 ⊢ (𝐴 ≠ ∅ ↔ ∃𝑥 𝑥 ∈ 𝐴) | |
2 | intss1 4968 | . . . . 5 ⊢ (𝑥 ∈ 𝐴 → ∩ 𝐴 ⊆ 𝑥) | |
3 | vex 3479 | . . . . . 6 ⊢ 𝑥 ∈ V | |
4 | 3 | ssex 5322 | . . . . 5 ⊢ (∩ 𝐴 ⊆ 𝑥 → ∩ 𝐴 ∈ V) |
5 | 2, 4 | syl 17 | . . . 4 ⊢ (𝑥 ∈ 𝐴 → ∩ 𝐴 ∈ V) |
6 | 5 | exlimiv 1934 | . . 3 ⊢ (∃𝑥 𝑥 ∈ 𝐴 → ∩ 𝐴 ∈ V) |
7 | 1, 6 | sylbi 216 | . 2 ⊢ (𝐴 ≠ ∅ → ∩ 𝐴 ∈ V) |
8 | vprc 5316 | . . . 4 ⊢ ¬ V ∈ V | |
9 | inteq 4954 | . . . . . 6 ⊢ (𝐴 = ∅ → ∩ 𝐴 = ∩ ∅) | |
10 | int0 4967 | . . . . . 6 ⊢ ∩ ∅ = V | |
11 | 9, 10 | eqtrdi 2789 | . . . . 5 ⊢ (𝐴 = ∅ → ∩ 𝐴 = V) |
12 | 11 | eleq1d 2819 | . . . 4 ⊢ (𝐴 = ∅ → (∩ 𝐴 ∈ V ↔ V ∈ V)) |
13 | 8, 12 | mtbiri 327 | . . 3 ⊢ (𝐴 = ∅ → ¬ ∩ 𝐴 ∈ V) |
14 | 13 | necon2ai 2971 | . 2 ⊢ (∩ 𝐴 ∈ V → 𝐴 ≠ ∅) |
15 | 7, 14 | impbii 208 | 1 ⊢ (𝐴 ≠ ∅ ↔ ∩ 𝐴 ∈ V) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 205 = wceq 1542 ∃wex 1782 ∈ wcel 2107 ≠ wne 2941 Vcvv 3475 ⊆ wss 3949 ∅c0 4323 ∩ cint 4951 |
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 ax-sep 5300 |
This theorem depends on definitions: df-bi 206 df-an 398 df-tru 1545 df-fal 1555 df-ex 1783 df-sb 2069 df-clab 2711 df-cleq 2725 df-clel 2811 df-ne 2942 df-ral 3063 df-rex 3072 df-rab 3434 df-v 3477 df-dif 3952 df-in 3956 df-ss 3966 df-nul 4324 df-int 4952 |
This theorem is referenced by: intnex 5339 intexab 5340 iinexg 5342 onint0 7779 onintrab 7784 onmindif2 7795 fival 9407 elfi2 9409 elfir 9410 dffi2 9418 elfiun 9425 fifo 9427 tz9.1c 9725 tz9.12lem1 9782 tz9.12lem3 9784 rankf 9789 cardf2 9938 cardval3 9947 cardid2 9948 cardcf 10247 cflim2 10258 intwun 10730 wuncval 10737 inttsk 10769 intgru 10809 gruina 10813 dfrtrcl2 15009 mremre 17548 mrcval 17554 asplss 21428 aspsubrg 21430 toponmre 22597 subbascn 22758 zarclsint 32852 insiga 33135 sigagenval 33138 sigagensiga 33139 dmsigagen 33142 dfon2lem8 34762 dfon2lem9 34763 bj-snmoore 35994 igenval 36929 pclvalN 38761 elrfi 41432 ismrcd1 41436 mzpval 41470 dmmzp 41471 oninfex2 41994 salgenval 45037 intsal 45046 |
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