Theorem 1stctop 21246

Description: A first-countable topology is a topology. (Contributed by Jeff Hankins, 22-Aug-2009.)

Assertion

Ref	Expression
1stctop	⊢ (𝐽 ∈ 1st𝜔 → 𝐽 ∈ Top)

Proof of Theorem 1stctop

Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		eqid 2622	. . 3 ⊢ ∪ 𝐽 = ∪ 𝐽
2	1	is1stc 21244	. 2 ⊢ (𝐽 ∈ 1st𝜔 ↔ (𝐽 ∈ Top ∧ ∀𝑥 ∈ ∪ 𝐽∃𝑦 ∈ 𝒫 𝐽(𝑦 ≼ ω ∧ ∀𝑧 ∈ 𝐽 (𝑥 ∈ 𝑧 → 𝑥 ∈ ∪ (𝑦 ∩ 𝒫 𝑧)))))
3	2	simplbi 476	1 ⊢ (𝐽 ∈ 1st𝜔 → 𝐽 ∈ Top)

Syntax hints:   → wi 4   ∧ wa 384   ∈ wcel 1990  ∀wral 2912  ∃wrex 2913   ∩ cin 3573  𝒫 cpw 4158  ∪ cuni 4436   class class class wbr 4653  ωcom 7065   ≼ cdom 7953  Topctop 20698  1^st𝜔c1stc 21240

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ral 2917  df-rex 2918  df-rab 2921  df-v 3202  df-in 3581  df-ss 3588  df-pw 4160  df-uni 4437  df-1stc 21242

This theorem is referenced by:  1stcfb  21248  1stcrest  21256  1stcelcls  21264  lly1stc  21299  1stckgen  21357  tx1stc  21453