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Theorem coss2 5812
Description: Subclass theorem for composition. (Contributed by NM, 5-Apr-2013.)
Assertion
Ref Expression
coss2 (𝐴𝐵 → (𝐶𝐴) ⊆ (𝐶𝐵))

Proof of Theorem coss2
Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 ssbr 5149 . . . . 5 (𝐴𝐵 → (𝑥𝐴𝑦𝑥𝐵𝑦))
21anim1d 611 . . . 4 (𝐴𝐵 → ((𝑥𝐴𝑦𝑦𝐶𝑧) → (𝑥𝐵𝑦𝑦𝐶𝑧)))
32eximdv 1920 . . 3 (𝐴𝐵 → (∃𝑦(𝑥𝐴𝑦𝑦𝐶𝑧) → ∃𝑦(𝑥𝐵𝑦𝑦𝐶𝑧)))
43ssopab2dv 5508 . 2 (𝐴𝐵 → {⟨𝑥, 𝑧⟩ ∣ ∃𝑦(𝑥𝐴𝑦𝑦𝐶𝑧)} ⊆ {⟨𝑥, 𝑧⟩ ∣ ∃𝑦(𝑥𝐵𝑦𝑦𝐶𝑧)})
5 df-co 5642 . 2 (𝐶𝐴) = {⟨𝑥, 𝑧⟩ ∣ ∃𝑦(𝑥𝐴𝑦𝑦𝐶𝑧)}
6 df-co 5642 . 2 (𝐶𝐵) = {⟨𝑥, 𝑧⟩ ∣ ∃𝑦(𝑥𝐵𝑦𝑦𝐶𝑧)}
74, 5, 63sstr4g 3989 1 (𝐴𝐵 → (𝐶𝐴) ⊆ (𝐶𝐵))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 396  wex 1781  wss 3910   class class class wbr 5105  {copab 5167  ccom 5637
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-ext 2707
This theorem depends on definitions:  df-bi 206  df-an 397  df-tru 1544  df-ex 1782  df-sb 2068  df-clab 2714  df-cleq 2728  df-clel 2814  df-v 3447  df-in 3917  df-ss 3927  df-br 5106  df-opab 5168  df-co 5642
This theorem is referenced by:  coeq2  5814  funss  6520  tposss  8157  dftpos4  8175  ttrclco  9653  frmin  9684  frrlem16  9693  rtrclreclem4  14945  tsrdir  18492  mvdco  19225  ustex2sym  23566  ustex3sym  23567  ustneism  23573  trust  23579  utop2nei  23600  neipcfilu  23646  fcoinver  31472  trclubgNEW  41871  trrelsuperrel2dg  41924
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