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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 4359 | . . 3 ⊢ (𝐴 ≠ ∅ ↔ ∃𝑥 𝑥 ∈ 𝐴) | |
2 | intss1 4968 | . . . . 5 ⊢ (𝑥 ∈ 𝐴 → ∩ 𝐴 ⊆ 𝑥) | |
3 | vex 3482 | . . . . . 6 ⊢ 𝑥 ∈ V | |
4 | 3 | ssex 5327 | . . . . 5 ⊢ (∩ 𝐴 ⊆ 𝑥 → ∩ 𝐴 ∈ V) |
5 | 2, 4 | syl 17 | . . . 4 ⊢ (𝑥 ∈ 𝐴 → ∩ 𝐴 ∈ V) |
6 | 5 | exlimiv 1928 | . . 3 ⊢ (∃𝑥 𝑥 ∈ 𝐴 → ∩ 𝐴 ∈ V) |
7 | 1, 6 | sylbi 217 | . 2 ⊢ (𝐴 ≠ ∅ → ∩ 𝐴 ∈ V) |
8 | vprc 5321 | . . . 4 ⊢ ¬ V ∈ V | |
9 | inteq 4954 | . . . . . 6 ⊢ (𝐴 = ∅ → ∩ 𝐴 = ∩ ∅) | |
10 | int0 4967 | . . . . . 6 ⊢ ∩ ∅ = V | |
11 | 9, 10 | eqtrdi 2791 | . . . . 5 ⊢ (𝐴 = ∅ → ∩ 𝐴 = V) |
12 | 11 | eleq1d 2824 | . . . 4 ⊢ (𝐴 = ∅ → (∩ 𝐴 ∈ V ↔ V ∈ V)) |
13 | 8, 12 | mtbiri 327 | . . 3 ⊢ (𝐴 = ∅ → ¬ ∩ 𝐴 ∈ V) |
14 | 13 | necon2ai 2968 | . 2 ⊢ (∩ 𝐴 ∈ V → 𝐴 ≠ ∅) |
15 | 7, 14 | impbii 209 | 1 ⊢ (𝐴 ≠ ∅ ↔ ∩ 𝐴 ∈ V) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 206 = wceq 1537 ∃wex 1776 ∈ wcel 2106 ≠ wne 2938 Vcvv 3478 ⊆ wss 3963 ∅c0 4339 ∩ cint 4951 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-ext 2706 ax-sep 5302 |
This theorem depends on definitions: df-bi 207 df-an 396 df-3an 1088 df-tru 1540 df-fal 1550 df-ex 1777 df-sb 2063 df-clab 2713 df-cleq 2727 df-clel 2814 df-ne 2939 df-ral 3060 df-rex 3069 df-rab 3434 df-v 3480 df-dif 3966 df-in 3970 df-ss 3980 df-nul 4340 df-int 4952 |
This theorem is referenced by: intnex 5351 intexab 5352 iinexg 5354 onint0 7811 onintrab 7816 onmindif2 7827 fival 9450 elfi2 9452 elfir 9453 dffi2 9461 elfiun 9468 fifo 9470 tz9.1c 9768 tz9.12lem1 9825 tz9.12lem3 9827 rankf 9832 cardf2 9981 cardval3 9990 cardid2 9991 cardcf 10290 cflim2 10301 intwun 10773 wuncval 10780 inttsk 10812 intgru 10852 gruina 10856 dfrtrcl2 15098 mremre 17649 mrcval 17655 asplss 21912 aspsubrg 21914 toponmre 23117 subbascn 23278 zarclsint 33833 insiga 34118 sigagenval 34121 sigagensiga 34122 dmsigagen 34125 dfon2lem8 35772 dfon2lem9 35773 bj-snmoore 37096 igenval 38048 pclvalN 39873 elrfi 42682 ismrcd1 42686 mzpval 42720 dmmzp 42721 oninfex2 43234 salgenval 46277 intsal 46286 |
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