MPE Home Metamath Proof Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >  sbcco2 Structured version   Visualization version   GIF version

Theorem sbcco2 3492
Description: A composition law for class substitution. Importantly, 𝑥 may occur free in the class expression substituted for 𝐴. (Contributed by NM, 5-Sep-2004.) (Proof shortened by Andrew Salmon, 8-Jun-2011.)
Hypothesis
Ref Expression
sbcco2.1 (𝑥 = 𝑦𝐴 = 𝐵)
Assertion
Ref Expression
sbcco2 ([𝑥 / 𝑦][𝐵 / 𝑥]𝜑[𝐴 / 𝑥]𝜑)
Distinct variable groups:   𝑥,𝑦   𝜑,𝑦   𝑦,𝐴
Allowed substitution hints:   𝜑(𝑥)   𝐴(𝑥)   𝐵(𝑥,𝑦)

Proof of Theorem sbcco2
StepHypRef Expression
1 sbsbc 3472 . 2 ([𝑥 / 𝑦][𝐵 / 𝑥]𝜑[𝑥 / 𝑦][𝐵 / 𝑥]𝜑)
2 nfv 1883 . . 3 𝑦[𝐴 / 𝑥]𝜑
3 sbcco2.1 . . . . 5 (𝑥 = 𝑦𝐴 = 𝐵)
43equcoms 1993 . . . 4 (𝑦 = 𝑥𝐴 = 𝐵)
5 dfsbcq 3470 . . . . 5 (𝐴 = 𝐵 → ([𝐴 / 𝑥]𝜑[𝐵 / 𝑥]𝜑))
65bicomd 213 . . . 4 (𝐴 = 𝐵 → ([𝐵 / 𝑥]𝜑[𝐴 / 𝑥]𝜑))
74, 6syl 17 . . 3 (𝑦 = 𝑥 → ([𝐵 / 𝑥]𝜑[𝐴 / 𝑥]𝜑))
82, 7sbie 2436 . 2 ([𝑥 / 𝑦][𝐵 / 𝑥]𝜑[𝐴 / 𝑥]𝜑)
91, 8bitr3i 266 1 ([𝑥 / 𝑦][𝐵 / 𝑥]𝜑[𝐴 / 𝑥]𝜑)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196   = wceq 1523  [wsb 1937  [wsbc 3468
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-9 2039  ax-10 2059  ax-12 2087  ax-13 2282  ax-ext 2631
This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-ex 1745  df-nf 1750  df-sb 1938  df-clab 2638  df-cleq 2644  df-clel 2647  df-sbc 3469
This theorem is referenced by:  tfinds2  7105
  Copyright terms: Public domain W3C validator