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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 4310 | . . 3 ⊢ (𝐴 ≠ ∅ ↔ ∃𝑥 𝑥 ∈ 𝐴) | |
2 | intss1 4891 | . . . . 5 ⊢ (𝑥 ∈ 𝐴 → ∩ 𝐴 ⊆ 𝑥) | |
3 | vex 3497 | . . . . . 6 ⊢ 𝑥 ∈ V | |
4 | 3 | ssex 5225 | . . . . 5 ⊢ (∩ 𝐴 ⊆ 𝑥 → ∩ 𝐴 ∈ V) |
5 | 2, 4 | syl 17 | . . . 4 ⊢ (𝑥 ∈ 𝐴 → ∩ 𝐴 ∈ V) |
6 | 5 | exlimiv 1931 | . . 3 ⊢ (∃𝑥 𝑥 ∈ 𝐴 → ∩ 𝐴 ∈ V) |
7 | 1, 6 | sylbi 219 | . 2 ⊢ (𝐴 ≠ ∅ → ∩ 𝐴 ∈ V) |
8 | vprc 5219 | . . . 4 ⊢ ¬ V ∈ V | |
9 | inteq 4879 | . . . . . 6 ⊢ (𝐴 = ∅ → ∩ 𝐴 = ∩ ∅) | |
10 | int0 4890 | . . . . . 6 ⊢ ∩ ∅ = V | |
11 | 9, 10 | syl6eq 2872 | . . . . 5 ⊢ (𝐴 = ∅ → ∩ 𝐴 = V) |
12 | 11 | eleq1d 2897 | . . . 4 ⊢ (𝐴 = ∅ → (∩ 𝐴 ∈ V ↔ V ∈ V)) |
13 | 8, 12 | mtbiri 329 | . . 3 ⊢ (𝐴 = ∅ → ¬ ∩ 𝐴 ∈ V) |
14 | 13 | necon2ai 3045 | . 2 ⊢ (∩ 𝐴 ∈ V → 𝐴 ≠ ∅) |
15 | 7, 14 | impbii 211 | 1 ⊢ (𝐴 ≠ ∅ ↔ ∩ 𝐴 ∈ V) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 208 = wceq 1537 ∃wex 1780 ∈ wcel 2114 ≠ wne 3016 Vcvv 3494 ⊆ wss 3936 ∅c0 4291 ∩ cint 4876 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 ax-sep 5203 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-ral 3143 df-rab 3147 df-v 3496 df-dif 3939 df-in 3943 df-ss 3952 df-nul 4292 df-int 4877 |
This theorem is referenced by: intnex 5241 intexab 5242 iinexg 5244 onint0 7511 onintrab 7516 onmindif2 7527 fival 8876 elfi2 8878 elfir 8879 dffi2 8887 elfiun 8894 fifo 8896 tz9.1c 9172 tz9.12lem1 9216 tz9.12lem3 9218 rankf 9223 cardf2 9372 cardval3 9381 cardid2 9382 cardcf 9674 cflim2 9685 intwun 10157 wuncval 10164 inttsk 10196 intgru 10236 gruina 10240 dfrtrcl2 14421 mremre 16875 mrcval 16881 asplss 20103 aspsubrg 20105 toponmre 21701 subbascn 21862 insiga 31396 sigagenval 31399 sigagensiga 31400 dmsigagen 31403 dfon2lem8 33035 dfon2lem9 33036 bj-snmoore 34408 igenval 35354 pclvalN 37041 elrfi 39311 ismrcd1 39315 mzpval 39349 dmmzp 39350 salgenval 42626 intsal 42633 |
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