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Theorem predpredss 6153
Description: If 𝐴 is a subset of 𝐵, then their predecessor classes are also subsets. (Contributed by Scott Fenton, 2-Feb-2011.)
Assertion
Ref Expression
predpredss (𝐴𝐵 → Pred(𝑅, 𝐴, 𝑋) ⊆ Pred(𝑅, 𝐵, 𝑋))

Proof of Theorem predpredss
StepHypRef Expression
1 ssrin 4214 . 2 (𝐴𝐵 → (𝐴 ∩ (𝑅 “ {𝑋})) ⊆ (𝐵 ∩ (𝑅 “ {𝑋})))
2 df-pred 6147 . 2 Pred(𝑅, 𝐴, 𝑋) = (𝐴 ∩ (𝑅 “ {𝑋}))
3 df-pred 6147 . 2 Pred(𝑅, 𝐵, 𝑋) = (𝐵 ∩ (𝑅 “ {𝑋}))
41, 2, 33sstr4g 4016 1 (𝐴𝐵 → Pred(𝑅, 𝐴, 𝑋) ⊆ Pred(𝑅, 𝐵, 𝑋))
Colors of variables: wff setvar class
Syntax hints:  wi 4  cin 3939  wss 3940  {csn 4564  ccnv 5553  cima 5557  Predcpred 6146
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1904  ax-6 1963  ax-7 2008  ax-8 2109  ax-9 2117  ax-10 2138  ax-11 2153  ax-12 2169  ax-ext 2798
This theorem depends on definitions:  df-bi 208  df-an 397  df-or 844  df-tru 1533  df-ex 1774  df-nf 1778  df-sb 2063  df-clab 2805  df-cleq 2819  df-clel 2898  df-nfc 2968  df-v 3502  df-in 3947  df-ss 3956  df-pred 6147
This theorem is referenced by:  preddowncl  6174  wfrlem8  7958
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