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Theorem in4 3180
 Description: Rearrangement of intersection of 4 classes. (Contributed by NM, 21-Apr-2001.)
Assertion
Ref Expression
in4 ((𝐴𝐵) ∩ (𝐶𝐷)) = ((𝐴𝐶) ∩ (𝐵𝐷))

Proof of Theorem in4
StepHypRef Expression
1 in12 3175 . . 3 (𝐵 ∩ (𝐶𝐷)) = (𝐶 ∩ (𝐵𝐷))
21ineq2i 3162 . 2 (𝐴 ∩ (𝐵 ∩ (𝐶𝐷))) = (𝐴 ∩ (𝐶 ∩ (𝐵𝐷)))
3 inass 3174 . 2 ((𝐴𝐵) ∩ (𝐶𝐷)) = (𝐴 ∩ (𝐵 ∩ (𝐶𝐷)))
4 inass 3174 . 2 ((𝐴𝐶) ∩ (𝐵𝐷)) = (𝐴 ∩ (𝐶 ∩ (𝐵𝐷)))
52, 3, 43eqtr4i 2086 1 ((𝐴𝐵) ∩ (𝐶𝐷)) = ((𝐴𝐶) ∩ (𝐵𝐷))
 Colors of variables: wff set class Syntax hints:   = wceq 1259   ∩ cin 2943 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-io 640  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-10 1412  ax-11 1413  ax-i12 1414  ax-bndl 1415  ax-4 1416  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038 This theorem depends on definitions:  df-bi 114  df-tru 1262  df-nf 1366  df-sb 1662  df-clab 2043  df-cleq 2049  df-clel 2052  df-nfc 2183  df-v 2576  df-in 2951 This theorem is referenced by:  inindi  3181  inindir  3182
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