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Theorem 0ntr 21386
Description: A subset with an empty interior cannot cover a whole (nonempty) topology. (Contributed by NM, 12-Sep-2006.)
Hypothesis
Ref Expression
clscld.1 𝑋 = 𝐽
Assertion
Ref Expression
0ntr (((𝐽 ∈ Top ∧ 𝑋 ≠ ∅) ∧ (𝑆𝑋 ∧ ((int‘𝐽)‘𝑆) = ∅)) → (𝑋𝑆) ≠ ∅)

Proof of Theorem 0ntr
StepHypRef Expression
1 ssdif0 4211 . . . . 5 (𝑋𝑆 ↔ (𝑋𝑆) = ∅)
2 eqss 3875 . . . . . . . . 9 (𝑆 = 𝑋 ↔ (𝑆𝑋𝑋𝑆))
3 fveq2 6501 . . . . . . . . . . . . 13 (𝑆 = 𝑋 → ((int‘𝐽)‘𝑆) = ((int‘𝐽)‘𝑋))
4 clscld.1 . . . . . . . . . . . . . 14 𝑋 = 𝐽
54ntrtop 21385 . . . . . . . . . . . . 13 (𝐽 ∈ Top → ((int‘𝐽)‘𝑋) = 𝑋)
63, 5sylan9eqr 2836 . . . . . . . . . . . 12 ((𝐽 ∈ Top ∧ 𝑆 = 𝑋) → ((int‘𝐽)‘𝑆) = 𝑋)
76eqeq1d 2780 . . . . . . . . . . 11 ((𝐽 ∈ Top ∧ 𝑆 = 𝑋) → (((int‘𝐽)‘𝑆) = ∅ ↔ 𝑋 = ∅))
87biimpd 221 . . . . . . . . . 10 ((𝐽 ∈ Top ∧ 𝑆 = 𝑋) → (((int‘𝐽)‘𝑆) = ∅ → 𝑋 = ∅))
98ex 405 . . . . . . . . 9 (𝐽 ∈ Top → (𝑆 = 𝑋 → (((int‘𝐽)‘𝑆) = ∅ → 𝑋 = ∅)))
102, 9syl5bir 235 . . . . . . . 8 (𝐽 ∈ Top → ((𝑆𝑋𝑋𝑆) → (((int‘𝐽)‘𝑆) = ∅ → 𝑋 = ∅)))
1110expd 408 . . . . . . 7 (𝐽 ∈ Top → (𝑆𝑋 → (𝑋𝑆 → (((int‘𝐽)‘𝑆) = ∅ → 𝑋 = ∅))))
1211com34 91 . . . . . 6 (𝐽 ∈ Top → (𝑆𝑋 → (((int‘𝐽)‘𝑆) = ∅ → (𝑋𝑆𝑋 = ∅))))
1312imp32 411 . . . . 5 ((𝐽 ∈ Top ∧ (𝑆𝑋 ∧ ((int‘𝐽)‘𝑆) = ∅)) → (𝑋𝑆𝑋 = ∅))
141, 13syl5bir 235 . . . 4 ((𝐽 ∈ Top ∧ (𝑆𝑋 ∧ ((int‘𝐽)‘𝑆) = ∅)) → ((𝑋𝑆) = ∅ → 𝑋 = ∅))
1514necon3d 2988 . . 3 ((𝐽 ∈ Top ∧ (𝑆𝑋 ∧ ((int‘𝐽)‘𝑆) = ∅)) → (𝑋 ≠ ∅ → (𝑋𝑆) ≠ ∅))
1615imp 398 . 2 (((𝐽 ∈ Top ∧ (𝑆𝑋 ∧ ((int‘𝐽)‘𝑆) = ∅)) ∧ 𝑋 ≠ ∅) → (𝑋𝑆) ≠ ∅)
1716an32s 639 1 (((𝐽 ∈ Top ∧ 𝑋 ≠ ∅) ∧ (𝑆𝑋 ∧ ((int‘𝐽)‘𝑆) = ∅)) → (𝑋𝑆) ≠ ∅)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 387   = wceq 1507  wcel 2050  wne 2967  cdif 3828  wss 3831  c0 4180   cuni 4713  cfv 6190  Topctop 21208  intcnt 21332
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1758  ax-4 1772  ax-5 1869  ax-6 1928  ax-7 1965  ax-8 2052  ax-9 2059  ax-10 2079  ax-11 2093  ax-12 2106  ax-13 2301  ax-ext 2750  ax-rep 5050  ax-sep 5061  ax-nul 5068  ax-pow 5120  ax-pr 5187  ax-un 7281
This theorem depends on definitions:  df-bi 199  df-an 388  df-or 834  df-3an 1070  df-tru 1510  df-ex 1743  df-nf 1747  df-sb 2016  df-mo 2547  df-eu 2583  df-clab 2759  df-cleq 2771  df-clel 2846  df-nfc 2918  df-ne 2968  df-ral 3093  df-rex 3094  df-reu 3095  df-rab 3097  df-v 3417  df-sbc 3684  df-csb 3789  df-dif 3834  df-un 3836  df-in 3838  df-ss 3845  df-nul 4181  df-if 4352  df-pw 4425  df-sn 4443  df-pr 4445  df-op 4449  df-uni 4714  df-iun 4795  df-br 4931  df-opab 4993  df-mpt 5010  df-id 5313  df-xp 5414  df-rel 5415  df-cnv 5416  df-co 5417  df-dm 5418  df-rn 5419  df-res 5420  df-ima 5421  df-iota 6154  df-fun 6192  df-fn 6193  df-f 6194  df-f1 6195  df-fo 6196  df-f1o 6197  df-fv 6198  df-top 21209  df-ntr 21335
This theorem is referenced by: (None)
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