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Theorem bwth 22561
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 pm3.24 403 . . . . . . 7 ¬ ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin)
21a1i 11 . . . . . 6 (𝑏𝑧 → ¬ ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin))
32nrex 3197 . . . . 5 ¬ ∃𝑏𝑧 ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin)
4 r19.29 3184 . . . . 5 ((∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin) → ∃𝑏𝑧 ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin))
53, 4mto 196 . . . 4 ¬ (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
65a1i 11 . . 3 (𝑧 ∈ (𝒫 𝐽 ∩ Fin) → ¬ (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin))
76nrex 3197 . 2 ¬ ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
8 ralnex 3167 . . . . . 6 (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
9 cmptop 22546 . . . . . . 7 (𝐽 ∈ Comp → 𝐽 ∈ Top)
10 bwt2.1 . . . . . . . . . . 11 𝑋 = 𝐽
1110islp3 22297 . . . . . . . . . 10 ((𝐽 ∈ Top ∧ 𝐴𝑋𝑥𝑋) → (𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
12113expa 1117 . . . . . . . . 9 (((𝐽 ∈ Top ∧ 𝐴𝑋) ∧ 𝑥𝑋) → (𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
1312notbid 318 . . . . . . . 8 (((𝐽 ∈ Top ∧ 𝐴𝑋) ∧ 𝑥𝑋) → (¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
1413ralbidva 3111 . . . . . . 7 ((𝐽 ∈ Top ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
159, 14sylan 580 . . . . . 6 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
168, 15bitr3id 285 . . . . 5 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
17 rexanali 3192 . . . . . . . . 9 (∃𝑏𝐽 (𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) ↔ ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅))
18 nne 2947 . . . . . . . . . . . 12 (¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅ ↔ (𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅)
19 vex 3436 . . . . . . . . . . . . 13 𝑥 ∈ V
20 sneq 4571 . . . . . . . . . . . . . . . 16 (𝑜 = 𝑥 → {𝑜} = {𝑥})
2120difeq2d 4057 . . . . . . . . . . . . . . 15 (𝑜 = 𝑥 → (𝐴 ∖ {𝑜}) = (𝐴 ∖ {𝑥}))
2221ineq2d 4146 . . . . . . . . . . . . . 14 (𝑜 = 𝑥 → (𝑏 ∩ (𝐴 ∖ {𝑜})) = (𝑏 ∩ (𝐴 ∖ {𝑥})))
2322eqeq1d 2740 . . . . . . . . . . . . 13 (𝑜 = 𝑥 → ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ ↔ (𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅))
2419, 23spcev 3545 . . . . . . . . . . . 12 ((𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅ → ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)
2518, 24sylbi 216 . . . . . . . . . . 11 (¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅ → ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)
2625anim2i 617 . . . . . . . . . 10 ((𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2726reximi 3178 . . . . . . . . 9 (∃𝑏𝐽 (𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2817, 27sylbir 234 . . . . . . . 8 (¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2928ralimi 3087 . . . . . . 7 (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
3010cmpcov2 22541 . . . . . . . 8 ((𝐽 ∈ Comp ∧ ∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
3130ex 413 . . . . . . 7 (𝐽 ∈ Comp → (∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3229, 31syl5 34 . . . . . 6 (𝐽 ∈ Comp → (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3332adantr 481 . . . . 5 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3416, 33sylbid 239 . . . 4 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
35343adant3 1131 . . 3 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
36 elinel2 4130 . . . . . . . 8 (𝑧 ∈ (𝒫 𝐽 ∩ Fin) → 𝑧 ∈ Fin)
37 sseq2 3947 . . . . . . . . . . . 12 (𝑋 = 𝑧 → (𝐴𝑋𝐴 𝑧))
3837biimpac 479 . . . . . . . . . . 11 ((𝐴𝑋𝑋 = 𝑧) → 𝐴 𝑧)
39 infssuni 9110 . . . . . . . . . . . . 13 ((¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin ∧ 𝐴 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
40393expa 1117 . . . . . . . . . . . 12 (((¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin) ∧ 𝐴 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4140ancoms 459 . . . . . . . . . . 11 ((𝐴 𝑧 ∧ (¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4238, 41sylan 580 . . . . . . . . . 10 (((𝐴𝑋𝑋 = 𝑧) ∧ (¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4342an42s 658 . . . . . . . . 9 (((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ (𝑧 ∈ Fin ∧ 𝑋 = 𝑧)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4443anassrs 468 . . . . . . . 8 ((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ Fin) ∧ 𝑋 = 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4536, 44sylanl2 678 . . . . . . 7 ((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) ∧ 𝑋 = 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
46 0fin 8954 . . . . . . . . . . . 12 ∅ ∈ Fin
47 eleq1 2826 . . . . . . . . . . . 12 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin ↔ ∅ ∈ Fin))
4846, 47mpbiri 257 . . . . . . . . . . 11 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin)
49 snfi 8834 . . . . . . . . . . 11 {𝑜} ∈ Fin
50 unfi 8955 . . . . . . . . . . 11 (((𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin ∧ {𝑜} ∈ Fin) → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin)
5148, 49, 50sylancl 586 . . . . . . . . . 10 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin)
52 ssun1 4106 . . . . . . . . . . . 12 𝑏 ⊆ (𝑏 ∪ {𝑜})
53 ssun1 4106 . . . . . . . . . . . . 13 𝐴 ⊆ (𝐴 ∪ {𝑜})
54 undif1 4409 . . . . . . . . . . . . 13 ((𝐴 ∖ {𝑜}) ∪ {𝑜}) = (𝐴 ∪ {𝑜})
5553, 54sseqtrri 3958 . . . . . . . . . . . 12 𝐴 ⊆ ((𝐴 ∖ {𝑜}) ∪ {𝑜})
56 ss2in 4170 . . . . . . . . . . . 12 ((𝑏 ⊆ (𝑏 ∪ {𝑜}) ∧ 𝐴 ⊆ ((𝐴 ∖ {𝑜}) ∪ {𝑜})) → (𝑏𝐴) ⊆ ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜})))
5752, 55, 56mp2an 689 . . . . . . . . . . 11 (𝑏𝐴) ⊆ ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜}))
58 incom 4135 . . . . . . . . . . 11 (𝐴𝑏) = (𝑏𝐴)
59 undir 4210 . . . . . . . . . . 11 ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) = ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜}))
6057, 58, 593sstr4i 3964 . . . . . . . . . 10 (𝐴𝑏) ⊆ ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜})
61 ssfi 8956 . . . . . . . . . 10 ((((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin ∧ (𝐴𝑏) ⊆ ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜})) → (𝐴𝑏) ∈ Fin)
6251, 60, 61sylancl 586 . . . . . . . . 9 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝐴𝑏) ∈ Fin)
6362exlimiv 1933 . . . . . . . 8 (∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝐴𝑏) ∈ Fin)
6463ralimi 3087 . . . . . . 7 (∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ∀𝑏𝑧 (𝐴𝑏) ∈ Fin)
6545, 64anim12ci 614 . . . . . 6 (((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) ∧ 𝑋 = 𝑧) ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin))
6665expl 458 . . . . 5 (((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) → ((𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
6766reximdva 3203 . . . 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 1129 . . 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 47 . 2 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
707, 69mt3i 149 1 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 205  wa 396  w3a 1086   = wceq 1539  wex 1782  wcel 2106  wne 2943  wral 3064  wrex 3065  cdif 3884  cun 3885  cin 3886  wss 3887  c0 4256  𝒫 cpw 4533  {csn 4561   cuni 4839  cfv 6433  Fincfn 8733  Topctop 22042  limPtclp 22285  Compccmp 22537
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 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-10 2137  ax-11 2154  ax-12 2171  ax-ext 2709  ax-rep 5209  ax-sep 5223  ax-nul 5230  ax-pow 5288  ax-pr 5352  ax-un 7588
This theorem depends on definitions:  df-bi 206  df-an 397  df-or 845  df-3or 1087  df-3an 1088  df-tru 1542  df-fal 1552  df-ex 1783  df-nf 1787  df-sb 2068  df-mo 2540  df-eu 2569  df-clab 2716  df-cleq 2730  df-clel 2816  df-nfc 2889  df-ne 2944  df-ral 3069  df-rex 3070  df-reu 3072  df-rab 3073  df-v 3434  df-sbc 3717  df-csb 3833  df-dif 3890  df-un 3892  df-in 3894  df-ss 3904  df-pss 3906  df-nul 4257  df-if 4460  df-pw 4535  df-sn 4562  df-pr 4564  df-op 4568  df-uni 4840  df-int 4880  df-iun 4926  df-iin 4927  df-br 5075  df-opab 5137  df-mpt 5158  df-tr 5192  df-id 5489  df-eprel 5495  df-po 5503  df-so 5504  df-fr 5544  df-we 5546  df-xp 5595  df-rel 5596  df-cnv 5597  df-co 5598  df-dm 5599  df-rn 5600  df-res 5601  df-ima 5602  df-ord 6269  df-on 6270  df-lim 6271  df-suc 6272  df-iota 6391  df-fun 6435  df-fn 6436  df-f 6437  df-f1 6438  df-fo 6439  df-f1o 6440  df-fv 6441  df-om 7713  df-1o 8297  df-en 8734  df-fin 8737  df-top 22043  df-cld 22170  df-ntr 22171  df-cls 22172  df-lp 22287  df-cmp 22538
This theorem is referenced by:  poimirlem30  35807  fourierdlem42  43690
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