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Theorem bwth 22020
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 pm3.24 405 . . . . . . 7 ¬ ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin)
21a1i 11 . . . . . 6 (𝑏𝑧 → ¬ ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin))
32nrex 3271 . . . . 5 ¬ ∃𝑏𝑧 ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin)
4 r19.29 3256 . . . . 5 ((∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin) → ∃𝑏𝑧 ((𝐴𝑏) ∈ Fin ∧ ¬ (𝐴𝑏) ∈ Fin))
53, 4mto 199 . . . 4 ¬ (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
65a1i 11 . . 3 (𝑧 ∈ (𝒫 𝐽 ∩ Fin) → ¬ (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin))
76nrex 3271 . 2 ¬ ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
8 ralnex 3238 . . . . . 6 (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
9 cmptop 22005 . . . . . . 7 (𝐽 ∈ Comp → 𝐽 ∈ Top)
10 bwt2.1 . . . . . . . . . . 11 𝑋 = 𝐽
1110islp3 21756 . . . . . . . . . 10 ((𝐽 ∈ Top ∧ 𝐴𝑋𝑥𝑋) → (𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
12113expa 1114 . . . . . . . . 9 (((𝐽 ∈ Top ∧ 𝐴𝑋) ∧ 𝑥𝑋) → (𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
1312notbid 320 . . . . . . . 8 (((𝐽 ∈ Top ∧ 𝐴𝑋) ∧ 𝑥𝑋) → (¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
1413ralbidva 3198 . . . . . . 7 ((𝐽 ∈ Top ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
159, 14sylan 582 . . . . . 6 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
168, 15syl5bbr 287 . . . . 5 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) ↔ ∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅)))
17 rexanali 3267 . . . . . . . . 9 (∃𝑏𝐽 (𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) ↔ ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅))
18 nne 3022 . . . . . . . . . . . 12 (¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅ ↔ (𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅)
19 vex 3499 . . . . . . . . . . . . 13 𝑥 ∈ V
20 sneq 4579 . . . . . . . . . . . . . . . 16 (𝑜 = 𝑥 → {𝑜} = {𝑥})
2120difeq2d 4101 . . . . . . . . . . . . . . 15 (𝑜 = 𝑥 → (𝐴 ∖ {𝑜}) = (𝐴 ∖ {𝑥}))
2221ineq2d 4191 . . . . . . . . . . . . . 14 (𝑜 = 𝑥 → (𝑏 ∩ (𝐴 ∖ {𝑜})) = (𝑏 ∩ (𝐴 ∖ {𝑥})))
2322eqeq1d 2825 . . . . . . . . . . . . 13 (𝑜 = 𝑥 → ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ ↔ (𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅))
2419, 23spcev 3609 . . . . . . . . . . . 12 ((𝑏 ∩ (𝐴 ∖ {𝑥})) = ∅ → ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)
2518, 24sylbi 219 . . . . . . . . . . 11 (¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅ → ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)
2625anim2i 618 . . . . . . . . . 10 ((𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2726reximi 3245 . . . . . . . . 9 (∃𝑏𝐽 (𝑥𝑏 ∧ ¬ (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2817, 27sylbir 237 . . . . . . . 8 (¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
2928ralimi 3162 . . . . . . 7 (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
3010cmpcov2 22000 . . . . . . . 8 ((𝐽 ∈ Comp ∧ ∀𝑥𝑋𝑏𝐽 (𝑥𝑏 ∧ ∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅))
3130ex 415 . . . . . . 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 483 . . . . 5 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (∀𝑥𝑋 ¬ ∀𝑏𝐽 (𝑥𝑏 → (𝑏 ∩ (𝐴 ∖ {𝑥})) ≠ ∅) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
3416, 33sylbid 242 . . . 4 ((𝐽 ∈ Comp ∧ 𝐴𝑋) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
35343adant3 1128 . . 3 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → (¬ ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴) → ∃𝑧 ∈ (𝒫 𝐽 ∩ Fin)(𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅)))
36 elinel2 4175 . . . . . . . 8 (𝑧 ∈ (𝒫 𝐽 ∩ Fin) → 𝑧 ∈ Fin)
37 sseq2 3995 . . . . . . . . . . . 12 (𝑋 = 𝑧 → (𝐴𝑋𝐴 𝑧))
3837biimpac 481 . . . . . . . . . . 11 ((𝐴𝑋𝑋 = 𝑧) → 𝐴 𝑧)
39 infssuni 8817 . . . . . . . . . . . . 13 ((¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin ∧ 𝐴 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
40393expa 1114 . . . . . . . . . . . 12 (((¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin) ∧ 𝐴 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4140ancoms 461 . . . . . . . . . . 11 ((𝐴 𝑧 ∧ (¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4238, 41sylan 582 . . . . . . . . . 10 (((𝐴𝑋𝑋 = 𝑧) ∧ (¬ 𝐴 ∈ Fin ∧ 𝑧 ∈ Fin)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4342an42s 659 . . . . . . . . 9 (((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ (𝑧 ∈ Fin ∧ 𝑋 = 𝑧)) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4443anassrs 470 . . . . . . . 8 ((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ Fin) ∧ 𝑋 = 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
4536, 44sylanl2 679 . . . . . . 7 ((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) ∧ 𝑋 = 𝑧) → ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)
46 0fin 8748 . . . . . . . . . . . 12 ∅ ∈ Fin
47 eleq1 2902 . . . . . . . . . . . 12 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin ↔ ∅ ∈ Fin))
4846, 47mpbiri 260 . . . . . . . . . . 11 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin)
49 snfi 8596 . . . . . . . . . . 11 {𝑜} ∈ Fin
50 unfi 8787 . . . . . . . . . . 11 (((𝑏 ∩ (𝐴 ∖ {𝑜})) ∈ Fin ∧ {𝑜} ∈ Fin) → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin)
5148, 49, 50sylancl 588 . . . . . . . . . 10 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin)
52 ssun1 4150 . . . . . . . . . . . 12 𝑏 ⊆ (𝑏 ∪ {𝑜})
53 ssun1 4150 . . . . . . . . . . . . 13 𝐴 ⊆ (𝐴 ∪ {𝑜})
54 undif1 4426 . . . . . . . . . . . . 13 ((𝐴 ∖ {𝑜}) ∪ {𝑜}) = (𝐴 ∪ {𝑜})
5553, 54sseqtrri 4006 . . . . . . . . . . . 12 𝐴 ⊆ ((𝐴 ∖ {𝑜}) ∪ {𝑜})
56 ss2in 4215 . . . . . . . . . . . 12 ((𝑏 ⊆ (𝑏 ∪ {𝑜}) ∧ 𝐴 ⊆ ((𝐴 ∖ {𝑜}) ∪ {𝑜})) → (𝑏𝐴) ⊆ ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜})))
5752, 55, 56mp2an 690 . . . . . . . . . . 11 (𝑏𝐴) ⊆ ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜}))
58 incom 4180 . . . . . . . . . . 11 (𝐴𝑏) = (𝑏𝐴)
59 undir 4255 . . . . . . . . . . 11 ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) = ((𝑏 ∪ {𝑜}) ∩ ((𝐴 ∖ {𝑜}) ∪ {𝑜}))
6057, 58, 593sstr4i 4012 . . . . . . . . . 10 (𝐴𝑏) ⊆ ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜})
61 ssfi 8740 . . . . . . . . . 10 ((((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜}) ∈ Fin ∧ (𝐴𝑏) ⊆ ((𝑏 ∩ (𝐴 ∖ {𝑜})) ∪ {𝑜})) → (𝐴𝑏) ∈ Fin)
6251, 60, 61sylancl 588 . . . . . . . . 9 ((𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝐴𝑏) ∈ Fin)
6362exlimiv 1931 . . . . . . . 8 (∃𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → (𝐴𝑏) ∈ Fin)
6463ralimi 3162 . . . . . . 7 (∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅ → ∀𝑏𝑧 (𝐴𝑏) ∈ Fin)
6545, 64anim12ci 615 . . . . . 6 (((((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) ∧ 𝑋 = 𝑧) ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin))
6665expl 460 . . . . 5 (((𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) ∧ 𝑧 ∈ (𝒫 𝐽 ∩ Fin)) → ((𝑋 = 𝑧 ∧ ∀𝑏𝑧𝑜(𝑏 ∩ (𝐴 ∖ {𝑜})) = ∅) → (∀𝑏𝑧 (𝐴𝑏) ∈ Fin ∧ ∃𝑏𝑧 ¬ (𝐴𝑏) ∈ Fin)))
6766reximdva 3276 . . . 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 1126 . . 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 151 1 ((𝐽 ∈ Comp ∧ 𝐴𝑋 ∧ ¬ 𝐴 ∈ Fin) → ∃𝑥𝑋 𝑥 ∈ ((limPt‘𝐽)‘𝐴))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 208  wa 398  w3a 1083   = wceq 1537  wex 1780  wcel 2114  wne 3018  wral 3140  wrex 3141  cdif 3935  cun 3936  cin 3937  wss 3938  c0 4293  𝒫 cpw 4541  {csn 4569   cuni 4840  cfv 6357  Fincfn 8511  Topctop 21503  limPtclp 21744  Compccmp 21996
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 2795  ax-rep 5192  ax-sep 5205  ax-nul 5212  ax-pow 5268  ax-pr 5332  ax-un 7463
This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-3or 1084  df-3an 1085  df-tru 1540  df-ex 1781  df-nf 1785  df-sb 2070  df-mo 2622  df-eu 2654  df-clab 2802  df-cleq 2816  df-clel 2895  df-nfc 2965  df-ne 3019  df-ral 3145  df-rex 3146  df-reu 3147  df-rab 3149  df-v 3498  df-sbc 3775  df-csb 3886  df-dif 3941  df-un 3943  df-in 3945  df-ss 3954  df-pss 3956  df-nul 4294  df-if 4470  df-pw 4543  df-sn 4570  df-pr 4572  df-tp 4574  df-op 4576  df-uni 4841  df-int 4879  df-iun 4923  df-iin 4924  df-br 5069  df-opab 5131  df-mpt 5149  df-tr 5175  df-id 5462  df-eprel 5467  df-po 5476  df-so 5477  df-fr 5516  df-we 5518  df-xp 5563  df-rel 5564  df-cnv 5565  df-co 5566  df-dm 5567  df-rn 5568  df-res 5569  df-ima 5570  df-pred 6150  df-ord 6196  df-on 6197  df-lim 6198  df-suc 6199  df-iota 6316  df-fun 6359  df-fn 6360  df-f 6361  df-f1 6362  df-fo 6363  df-f1o 6364  df-fv 6365  df-ov 7161  df-oprab 7162  df-mpo 7163  df-om 7583  df-wrecs 7949  df-recs 8010  df-rdg 8048  df-1o 8104  df-oadd 8108  df-er 8291  df-en 8512  df-fin 8515  df-top 21504  df-cld 21629  df-ntr 21630  df-cls 21631  df-lp 21746  df-cmp 21997
This theorem is referenced by:  poimirlem30  34924  fourierdlem42  42441
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