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Theorem 0nei 21712
Description: The empty set is a neighborhood of itself. (Contributed by FL, 10-Dec-2006.)
Assertion
Ref Expression
0nei (𝐽 ∈ Top → ∅ ∈ ((nei‘𝐽)‘∅))

Proof of Theorem 0nei
StepHypRef Expression
1 0opn 21488 . 2 (𝐽 ∈ Top → ∅ ∈ 𝐽)
2 opnneiid 21710 . 2 (𝐽 ∈ Top → (∅ ∈ ((nei‘𝐽)‘∅) ↔ ∅ ∈ 𝐽))
31, 2mpbird 260 1 (𝐽 ∈ Top → ∅ ∈ ((nei‘𝐽)‘∅))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wcel 2115  c0 4266  cfv 6328  Topctop 21477  neicnei 21681
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1971  ax-7 2016  ax-8 2117  ax-9 2125  ax-10 2146  ax-11 2162  ax-12 2178  ax-ext 2793  ax-rep 5163  ax-sep 5176  ax-nul 5183  ax-pow 5239  ax-pr 5303
This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2071  df-mo 2623  df-eu 2654  df-clab 2800  df-cleq 2814  df-clel 2892  df-nfc 2960  df-ne 3008  df-ral 3131  df-rex 3132  df-reu 3133  df-rab 3135  df-v 3473  df-sbc 3750  df-csb 3858  df-dif 3913  df-un 3915  df-in 3917  df-ss 3927  df-nul 4267  df-if 4441  df-pw 4514  df-sn 4541  df-pr 4543  df-op 4547  df-uni 4812  df-iun 4894  df-br 5040  df-opab 5102  df-mpt 5120  df-id 5433  df-xp 5534  df-rel 5535  df-cnv 5536  df-co 5537  df-dm 5538  df-rn 5539  df-res 5540  df-ima 5541  df-iota 6287  df-fun 6330  df-fn 6331  df-f 6332  df-f1 6333  df-fo 6334  df-f1o 6335  df-fv 6336  df-top 21478  df-nei 21682
This theorem is referenced by:  utop2nei  22835
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