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Theorem ntrdif 22876
Description: An interior of a complement is the complement of the closure. This set is also known as the exterior of 𝐴. (Contributed by Jeff Hankins, 31-Aug-2009.)
Hypothesis
Ref Expression
clscld.1 𝑋 = βˆͺ 𝐽
Assertion
Ref Expression
ntrdif ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ ((intβ€˜π½)β€˜(𝑋 βˆ– 𝐴)) = (𝑋 βˆ– ((clsβ€˜π½)β€˜π΄)))
Proof of Theorem ntrdif
StepHypRef Expression
1 difss 4131 . . . 4 (𝑋 βˆ– 𝐴) βŠ† 𝑋
2 clscld.1 . . . . 5 𝑋 = βˆͺ 𝐽
32ntrval2 22875 . . . 4 ((𝐽 ∈ Top ∧ (𝑋 βˆ– 𝐴) βŠ† 𝑋) β†’ ((intβ€˜π½)β€˜(𝑋 βˆ– 𝐴)) = (𝑋 βˆ– ((clsβ€˜π½)β€˜(𝑋 βˆ– (𝑋 βˆ– 𝐴)))))
41, 3mpan2 688 . . 3 (𝐽 ∈ Top β†’ ((intβ€˜π½)β€˜(𝑋 βˆ– 𝐴)) = (𝑋 βˆ– ((clsβ€˜π½)β€˜(𝑋 βˆ– (𝑋 βˆ– 𝐴)))))
54adantr 480 . 2 ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ ((intβ€˜π½)β€˜(𝑋 βˆ– 𝐴)) = (𝑋 βˆ– ((clsβ€˜π½)β€˜(𝑋 βˆ– (𝑋 βˆ– 𝐴)))))
6 simpr 484 . . . . 5 ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ 𝐴 βŠ† 𝑋)
7 dfss4 4258 . . . . 5 (𝐴 βŠ† 𝑋 ↔ (𝑋 βˆ– (𝑋 βˆ– 𝐴)) = 𝐴)
86, 7sylib 217 . . . 4 ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ (𝑋 βˆ– (𝑋 βˆ– 𝐴)) = 𝐴)
98fveq2d 6895 . . 3 ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ ((clsβ€˜π½)β€˜(𝑋 βˆ– (𝑋 βˆ– 𝐴))) = ((clsβ€˜π½)β€˜π΄))
109difeq2d 4122 . 2 ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ (𝑋 βˆ– ((clsβ€˜π½)β€˜(𝑋 βˆ– (𝑋 βˆ– 𝐴)))) = (𝑋 βˆ– ((clsβ€˜π½)β€˜π΄)))
115, 10eqtrd 2771 1 ((𝐽 ∈ Top ∧ 𝐴 βŠ† 𝑋) β†’ ((intβ€˜π½)β€˜(𝑋 βˆ– 𝐴)) = (𝑋 βˆ– ((clsβ€˜π½)β€˜π΄)))
Colors of variables: wff setvar class
Syntax hints:   β†’ wi 4   ∧ wa 395   = wceq 1540   ∈ wcel 2105   βˆ– cdif 3945   βŠ† wss 3948  βˆͺ cuni 4908  β€˜cfv 6543  Topctop 22715  intcnt 22841  clsccl 22842
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 1912  ax-6 1970  ax-7 2010  ax-8 2107  ax-9 2115  ax-10 2136  ax-11 2153  ax-12 2170  ax-ext 2702  ax-rep 5285  ax-sep 5299  ax-nul 5306  ax-pow 5363  ax-pr 5427  ax-un 7729
This theorem depends on definitions:  df-bi 206  df-an 396  df-or 845  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1781  df-nf 1785  df-sb 2067  df-mo 2533  df-eu 2562  df-clab 2709  df-cleq 2723  df-clel 2809  df-nfc 2884  df-ne 2940  df-ral 3061  df-rex 3070  df-reu 3376  df-rab 3432  df-v 3475  df-sbc 3778  df-csb 3894  df-dif 3951  df-un 3953  df-in 3955  df-ss 3965  df-nul 4323  df-if 4529  df-pw 4604  df-sn 4629  df-pr 4631  df-op 4635  df-uni 4909  df-int 4951  df-iun 4999  df-iin 5000  df-br 5149  df-opab 5211  df-mpt 5232  df-id 5574  df-xp 5682  df-rel 5683  df-cnv 5684  df-co 5685  df-dm 5686  df-rn 5687  df-res 5688  df-ima 5689  df-iota 6495  df-fun 6545  df-fn 6546  df-f 6547  df-f1 6548  df-fo 6549  df-f1o 6550  df-fv 6551  df-top 22716  df-cld 22843  df-ntr 22844  df-cls 22845
This theorem is referenced by:  clsun  35679
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