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Theorem cdleme31sdnN 40369
Description: Part of proof of Lemma E in [Crawley] p. 113. (Contributed by NM, 31-Mar-2013.) (New usage is discouraged.)
Hypotheses
Ref Expression
cdleme31sdn.c 𝐶 = ((𝑠 𝑈) (𝑄 ((𝑃 𝑠) 𝑊)))
cdleme31sdn.d 𝐷 = ((𝑡 𝑈) (𝑄 ((𝑃 𝑡) 𝑊)))
cdleme31sdn.n 𝑁 = if(𝑠 (𝑃 𝑄), 𝐼, 𝐶)
Assertion
Ref Expression
cdleme31sdnN 𝑁 = if(𝑠 (𝑃 𝑄), 𝐼, 𝑠 / 𝑡𝐷)
Distinct variable groups:   𝑡,   𝑡,   𝑡,𝑃   𝑡,𝑄   𝑡,𝑈   𝑡,𝑊   𝑡,𝑠
Allowed substitution hints:   𝐶(𝑡,𝑠)   𝐷(𝑡,𝑠)   𝑃(𝑠)   𝑄(𝑠)   𝑈(𝑠)   𝐼(𝑡,𝑠)   (𝑠)   (𝑡,𝑠)   (𝑠)   𝑁(𝑡,𝑠)   𝑊(𝑠)

Proof of Theorem cdleme31sdnN
StepHypRef Expression
1 cdleme31sdn.n . 2 𝑁 = if(𝑠 (𝑃 𝑄), 𝐼, 𝐶)
2 biid 261 . . 3 (𝑠 (𝑃 𝑄) ↔ 𝑠 (𝑃 𝑄))
3 cdleme31sdn.d . . . . 5 𝐷 = ((𝑡 𝑈) (𝑄 ((𝑃 𝑡) 𝑊)))
4 cdleme31sdn.c . . . . 5 𝐶 = ((𝑠 𝑈) (𝑄 ((𝑃 𝑠) 𝑊)))
53, 4cdleme31sc 40366 . . . 4 (𝑠 ∈ V → 𝑠 / 𝑡𝐷 = 𝐶)
65elv 3482 . . 3 𝑠 / 𝑡𝐷 = 𝐶
72, 6ifbieq2i 4555 . 2 if(𝑠 (𝑃 𝑄), 𝐼, 𝑠 / 𝑡𝐷) = if(𝑠 (𝑃 𝑄), 𝐼, 𝐶)
81, 7eqtr4i 2765 1 𝑁 = if(𝑠 (𝑃 𝑄), 𝐼, 𝑠 / 𝑡𝐷)
Colors of variables: wff setvar class
Syntax hints:   = wceq 1536  Vcvv 3477  csb 3907  ifcif 4530   class class class wbr 5147  (class class class)co 7430
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1791  ax-4 1805  ax-5 1907  ax-6 1964  ax-7 2004  ax-8 2107  ax-9 2115  ax-10 2138  ax-11 2154  ax-12 2174  ax-ext 2705
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1539  df-fal 1549  df-ex 1776  df-nf 1780  df-sb 2062  df-clab 2712  df-cleq 2726  df-clel 2813  df-nfc 2889  df-rab 3433  df-v 3479  df-sbc 3791  df-csb 3908  df-dif 3965  df-un 3967  df-ss 3979  df-nul 4339  df-if 4531  df-sn 4631  df-pr 4633  df-op 4637  df-uni 4912  df-br 5148  df-iota 6515  df-fv 6570  df-ov 7433
This theorem is referenced by: (None)
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