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Theorem tpnei 20835
Description: The underlying set of a topology is a neighborhood of any of its subsets. Special case of opnneiss 20832. (Contributed by FL, 2-Oct-2006.)
Hypothesis
Ref Expression
tpnei.1 𝑋 = 𝐽
Assertion
Ref Expression
tpnei (𝐽 ∈ Top → (𝑆𝑋𝑋 ∈ ((nei‘𝐽)‘𝑆)))

Proof of Theorem tpnei
StepHypRef Expression
1 tpnei.1 . . . 4 𝑋 = 𝐽
21topopn 20636 . . 3 (𝐽 ∈ Top → 𝑋𝐽)
3 opnneiss 20832 . . . 4 ((𝐽 ∈ Top ∧ 𝑋𝐽𝑆𝑋) → 𝑋 ∈ ((nei‘𝐽)‘𝑆))
433exp 1261 . . 3 (𝐽 ∈ Top → (𝑋𝐽 → (𝑆𝑋𝑋 ∈ ((nei‘𝐽)‘𝑆))))
52, 4mpd 15 . 2 (𝐽 ∈ Top → (𝑆𝑋𝑋 ∈ ((nei‘𝐽)‘𝑆)))
6 ssnei 20824 . . 3 ((𝐽 ∈ Top ∧ 𝑋 ∈ ((nei‘𝐽)‘𝑆)) → 𝑆𝑋)
76ex 450 . 2 (𝐽 ∈ Top → (𝑋 ∈ ((nei‘𝐽)‘𝑆) → 𝑆𝑋))
85, 7impbid 202 1 (𝐽 ∈ Top → (𝑆𝑋𝑋 ∈ ((nei‘𝐽)‘𝑆)))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196   = wceq 1480  wcel 1987  wss 3555   cuni 4402  cfv 5847  Topctop 20617  neicnei 20811
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-8 1989  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601  ax-rep 4731  ax-sep 4741  ax-nul 4749  ax-pow 4803  ax-pr 4867
This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3an 1038  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-eu 2473  df-mo 2474  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2750  df-ne 2791  df-ral 2912  df-rex 2913  df-reu 2914  df-rab 2916  df-v 3188  df-sbc 3418  df-csb 3515  df-dif 3558  df-un 3560  df-in 3562  df-ss 3569  df-nul 3892  df-if 4059  df-pw 4132  df-sn 4149  df-pr 4151  df-op 4155  df-uni 4403  df-iun 4487  df-br 4614  df-opab 4674  df-mpt 4675  df-id 4989  df-xp 5080  df-rel 5081  df-cnv 5082  df-co 5083  df-dm 5084  df-rn 5085  df-res 5086  df-ima 5087  df-iota 5810  df-fun 5849  df-fn 5850  df-f 5851  df-f1 5852  df-fo 5853  df-f1o 5854  df-fv 5855  df-top 20621  df-nei 20812
This theorem is referenced by:  neiuni  20836  neifil  21594  gneispa  37910
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