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Theorem bwth 23536
Description: The glorious Bolzano-Weierstrass theorem. The first general topology theorem ever proved. The first mention of this theorem can be found in a course by Weierstrass from 1865. In his course Weierstrass called it a lemma. He didn't know how famous this theorem would be. He used a Euclidean space instead of a general compact space. And he was not aware of the Heine-Borel property. But the concepts of neighborhood and limit point were already there although not precisely defined. Cantor was one of his students. He published and used the theorem in an article from 1872. The rest of the general topology followed from that. (Contributed by FL, 2-Aug-2009.) (Revised by Mario Carneiro, 15-Dec-2013.) Revised by BL to significantly shorten the proof and avoid infinity, regularity, and choice. (Revised by Brendan Leahy, 26-Dec-2018.)
Hypothesis
Ref Expression
bwt2.1 𝑋 = 𝐽
Assertion
Ref Expression
bwth ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐽   𝑥,𝑋

Proof of Theorem bwth
Dummy variables 𝑜 𝑏 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 pm3.24 407 . . . . . . 7 ¬ ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin)
21a1i 11 . . . . . 6 (𝑏𝑧 → ¬ ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin))
32nrex 3099 . . . . 5 ¬ ∃𝑏𝑧 ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin)
4 r19.29 3134 . . . . 5 ((∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin) → ∃𝑏𝑧 ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin))
53, 4mto 200 . . . 4 ¬ (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
65a1i 11 . . 3 (𝑧 ∈ (𝒫 𝐽 ∩ Fin) → ¬ (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin))
76nrex 3099 . 2 ¬ ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
8 ralnex 3097 . . . . . 6 (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
9 cmptop 23521 . . . . . . 7 (𝐽 ∈ Comp → 𝐽 ∈ Top)
10 bwt2.1 . . . . . . . . . . 11 𝑋 = 𝐽
1110islp3 23272 . . . . . . . . . 10 ((𝐽 ∈ Top ∧ 𝐴𝑋𝑥𝑋) → (𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
12113expa 1134 . . . . . . . . 9 (((𝐽 ∈ Top ∧ 𝐴𝑋) ∧ 𝑥𝑋) → (𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
1312notbid 321 . . . . . . . 8 (((𝐽 ∈ Top ∧ 𝐴𝑋) ∧ 𝑥𝑋) → (¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
1413ralbidva 3192 . . . . . . 7 ((𝐽 ∈ Top ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
159, 14sylan 591 . . . . . 6 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
168, 15bitr3id 288 . . . . 5 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
17 rexanali 3125 . . . . . . . . 9 (∃𝑏𝐽 (𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) ↔ ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅))
18 nne 2968 . . . . . . . . . . . 12 (¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅ ↔ (𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅)
19 vex 3465 . . . . . . . . . . . . 13 𝑥 ∈ V
20 sneq 4602 . . . . . . . . . . . . . . . 16 (𝑜 = 𝑥 → {𝑜} = {𝑥})
2120difeq2d 4087 . . . . . . . . . . . . . . 15 (𝑜 = 𝑥 → (𝐴 ∖ {𝑜}) = (𝐴 ∖ {𝑥}))
2221ineq2d 4179 . . . . . . . . . . . . . 14 (𝑜 = 𝑥 → (𝑏 ∩ (𝐴 ∖ {𝑜})) = (𝑏 ∩ (𝐴 ∖ {𝑥})))
2322eqeq1d 2771 . . . . . . . . . . . . 13 (𝑜 = 𝑥 → ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ ↔ (𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅))
2419, 23spcev 3572 . . . . . . . . . . . 12 ((𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅ → ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)
2518, 24sylbi 220 . . . . . . . . . . 11 (¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅ → ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)
2625anim2i 628 . . . . . . . . . 10 ((𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2726reximi 3109 . . . . . . . . 9 (∃𝑏𝐽 (𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2817, 27sylbir 238 . . . . . . . 8 (¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2928ralimi 3108 . . . . . . 7 (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
3010cmpcov2 23516 . . . . . . . 8 ((𝐽 ∈ Comp ∧ ∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
3130ex 417 . . . . . . 7 (𝐽 ∈ Comp → (∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3229, 31syl5 35 . . . . . 6 (𝐽 ∈ Comp → (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3332adantr 485 . . . . 5 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3416, 33sylbid 243 . . . 4 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
35343adant3 1148 . . 3 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
36 elinel2 4161 . . . . . . . 8 (𝑧 ∈ (𝒫 𝐽 ∩ Fin) → 𝑧 ∈ Fin)
37 sseq2 3969 . . . . . . . . . . . 12 (𝑋 = 𝑧 → (𝐴𝑋𝐴 𝑧))
3837biimpac 483 . . . . . . . . . . 11 ((𝐴𝑋𝑋 = 𝑧) → 𝐴 𝑧)
39 infssuni 9303 . . . . . . . . . . . . 13 ((¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin ∧ 𝐴 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
40393expa 1134 . . . . . . . . . . . 12 (((¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin) ∧ 𝐴 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4140ancoms 463 . . . . . . . . . . 11 ((𝐴 𝑧 ∧ (¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4238, 41sylan 591 . . . . . . . . . 10 (((𝐴𝑋𝑋 = 𝑧) ∧ (¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4342an42s 673 . . . . . . . . 9 (((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ (𝑧 ∈ Fin ∧ 𝑋 = 𝑧)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4443anassrs 472 . . . . . . . 8 ((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ Fin) ∧ 𝑋 = 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4536, 44sylanl2 693 . . . . . . 7 ((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) ∧ 𝑋 = 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
46 0fi 9039 . . . . . . . . . . . 12 ∅ ∈ Fin
47 eleq1 2857 . . . . . . . . . . . 12 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin ↔ ∅ ∈ Fin))
4846, 47mpbiri 261 . . . . . . . . . . 11 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin)
49 snfi 9040 . . . . . . . . . . 11 {𝑜} ∈ Fin
50 unfi 9155 . . . . . . . . . . 11 (((𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin ∧ {𝑜} ∈ Fin) → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin)
5148, 49, 50sylancl 597 . . . . . . . . . 10 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin)
52 ssun1 4137 . . . . . . . . . . . 12 𝑏 ⊆ (𝑏 ∪ {𝑜})
53 ssun1 4137 . . . . . . . . . . . . 13 𝐴 ⊆ (𝐴 ∪ {𝑜})
54 undif1 4440 . . . . . . . . . . . . 13 ((𝐴 ∖ {𝑜}) ∪ {𝑜}) = (𝐴 ∪ {𝑜})
5553, 54sseqtrri 3992 . . . . . . . . . . . 12 𝐴 ⊆ ((𝐴 ∖ {𝑜}) ∪ {𝑜})
56 ss2in 4203 . . . . . . . . . . . 12 ((𝑏 ⊆ (𝑏 ∪ {𝑜}) ∧ 𝐴 ⊆ ((𝐴 ∖ {𝑜}) ∪ {𝑜})) → (𝑏𝐴) ⊆ ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜})))
5752, 55, 56mp2an 704 . . . . . . . . . . 11 (𝑏𝐴) ⊆ ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜}))
58 incom 4168 . . . . . . . . . . 11 (𝐴𝑏) = (𝑏𝐴)
59 undir 4246 . . . . . . . . . . 11 ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) = ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜}))
6057, 58, 593sstr4i 3994 . . . . . . . . . 10 (𝐴𝑏) ⊆ ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜})
61 ssfi 9157 . . . . . . . . . 10 ((((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin ∧ (𝐴𝑏) ⊆ ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜})) → (𝐴𝑏) ∈ Fin)
6251, 60, 61sylancl 597 . . . . . . . . 9 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝐴𝑏) ∈ Fin)
6362exlimiv 1957 . . . . . . . 8 (∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝐴𝑏) ∈ Fin)
6463ralimi 3108 . . . . . . 7 (∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ∀𝑏𝑧 (𝐴𝑏) ∈ Fin)
6545, 64anim12ci 625 . . . . . 6 (((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) ∧ 𝑋 = 𝑧) ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin))
6665expl 462 . . . . 5 (((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) → ((𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
6766reximdva 3184 . . . 4 ((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
68673adant1 1146 . . 3 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
6935, 68syld 48 . 2 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
707, 69mt3i 150 1 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 209  wa 400  w3a 1101   = wceq 1567  wex 1806  wcel 2149  wne 2964  wral 3085  wrex 3095  cdif 3908  cun 3909  cin 3910  wss 3911  c0 4292  𝒫 cpw 4565  {csn 4592   cuni 4874  cfv 6537  Fincfn 8943  Topctop 23019  limPtclp 23260  Compccmp 23512
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1822  ax-4 1836  ax-5 1937  ax-6 1994  ax-7 2035  ax-8 2151  ax-9 2159  ax-10 2182  ax-11 2198  ax-12 2219  ax-ext 2741  ax-rep 5240  ax-sep 5259  ax-nul 5271  ax-pow 5337  ax-pr 5405  ax-un 7733
This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-3or 1102  df-3an 1103  df-tru 1570  df-fal 1580  df-ex 1807  df-nf 1811  df-sb 2098  df-mo 2573  df-eu 2603  df-clab 2748  df-cleq 2761  df-clel 2844  df-nfc 2918  df-ne 2965  df-ral 3086  df-rex 3096  df-reu 3376  df-rab 3423  df-v 3463  df-sbc 3752  df-csb 3860  df-dif 3914  df-un 3916  df-in 3918  df-ss 3928  df-pss 3931  df-nul 4293  df-if 4491  df-pw 4567  df-sn 4593  df-pr 4595  df-op 4599  df-uni 4875  df-int 4915  df-iun 4960  df-iin 4961  df-br 5112  df-opab 5176  df-mpt 5195  df-tr 5221  df-id 5557  df-eprel 5562  df-po 5570  df-so 5571  df-fr 5615  df-we 5617  df-xp 5668  df-rel 5669  df-cnv 5670  df-co 5671  df-dm 5672  df-rn 5673  df-res 5674  df-ima 5675  df-ord 6364  df-on 6365  df-lim 6366  df-suc 6367  df-iota 6493  df-fun 6539  df-fn 6540  df-f 6541  df-f1 6542  df-fo 6543  df-f1o 6544  df-fv 6545  df-om 7863  df-1o 8453  df-en 8944  df-fin 8947  df-top 23020  df-cld 23145  df-ntr 23146  df-cls 23147  df-lp 23262  df-cmp 23513
This theorem is referenced by:  poimirlem30  38224  fourierdlem42  46790
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