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Theorem csbcom 4135
Description: Commutative law for double substitution into a class. (Contributed by NM, 14-Nov-2005.) (Revised by NM, 18-Aug-2018.)
Assertion
Ref Expression
csbcom 𝐴 / 𝑥𝐵 / 𝑦𝐶 = 𝐵 / 𝑦𝐴 / 𝑥𝐶
Distinct variable groups:   𝑦,𝐴   𝑥,𝐵   𝑥,𝑦
Allowed substitution hints:   𝐴(𝑥)   𝐵(𝑦)   𝐶(𝑥,𝑦)

Proof of Theorem csbcom
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 sbccom 3648 . . . 4 ([𝐴 / 𝑥][𝐵 / 𝑦]𝑧𝐶[𝐵 / 𝑦][𝐴 / 𝑥]𝑧𝐶)
2 sbcel2 4130 . . . . 5 ([𝐵 / 𝑦]𝑧𝐶𝑧𝐵 / 𝑦𝐶)
32sbcbii 3630 . . . 4 ([𝐴 / 𝑥][𝐵 / 𝑦]𝑧𝐶[𝐴 / 𝑥]𝑧𝐵 / 𝑦𝐶)
4 sbcel2 4130 . . . . 5 ([𝐴 / 𝑥]𝑧𝐶𝑧𝐴 / 𝑥𝐶)
54sbcbii 3630 . . . 4 ([𝐵 / 𝑦][𝐴 / 𝑥]𝑧𝐶[𝐵 / 𝑦]𝑧𝐴 / 𝑥𝐶)
61, 3, 53bitr3i 290 . . 3 ([𝐴 / 𝑥]𝑧𝐵 / 𝑦𝐶[𝐵 / 𝑦]𝑧𝐴 / 𝑥𝐶)
7 sbcel2 4130 . . 3 ([𝐴 / 𝑥]𝑧𝐵 / 𝑦𝐶𝑧𝐴 / 𝑥𝐵 / 𝑦𝐶)
8 sbcel2 4130 . . 3 ([𝐵 / 𝑦]𝑧𝐴 / 𝑥𝐶𝑧𝐵 / 𝑦𝐴 / 𝑥𝐶)
96, 7, 83bitr3i 290 . 2 (𝑧𝐴 / 𝑥𝐵 / 𝑦𝐶𝑧𝐵 / 𝑦𝐴 / 𝑥𝐶)
109eqriv 2755 1 𝐴 / 𝑥𝐵 / 𝑦𝐶 = 𝐵 / 𝑦𝐴 / 𝑥𝐶
Colors of variables: wff setvar class
Syntax hints:   = wceq 1630  wcel 2137  [wsbc 3574  csb 3672
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1869  ax-4 1884  ax-5 1986  ax-6 2052  ax-7 2088  ax-9 2146  ax-10 2166  ax-11 2181  ax-12 2194  ax-13 2389  ax-ext 2738
This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-tru 1633  df-fal 1636  df-ex 1852  df-nf 1857  df-sb 2045  df-clab 2745  df-cleq 2751  df-clel 2754  df-nfc 2889  df-v 3340  df-sbc 3575  df-csb 3673  df-dif 3716  df-nul 4057
This theorem is referenced by:  ovmpt2s  6947  fvmpt2curryd  7564  f1od2  29806
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