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Theorem predpredss 6307
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 4233 . 2 (𝐴𝐵 → (𝐴 ∩ (𝑅 “ {𝑋})) ⊆ (𝐵 ∩ (𝑅 “ {𝑋})))
2 df-pred 6300 . 2 Pred(𝑅, 𝐴, 𝑋) = (𝐴 ∩ (𝑅 “ {𝑋}))
3 df-pred 6300 . 2 Pred(𝑅, 𝐵, 𝑋) = (𝐵 ∩ (𝑅 “ {𝑋}))
41, 2, 33sstr4g 4027 1 (𝐴𝐵 → Pred(𝑅, 𝐴, 𝑋) ⊆ Pred(𝑅, 𝐵, 𝑋))
Colors of variables: wff setvar class
Syntax hints:  wi 4  cin 3947  wss 3948  {csn 4628  ccnv 5675  cima 5679  Predcpred 6299
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1912  ax-6 1970  ax-7 2010  ax-8 2107  ax-9 2115  ax-ext 2702
This theorem depends on definitions:  df-bi 206  df-an 396  df-tru 1543  df-ex 1781  df-sb 2067  df-clab 2709  df-cleq 2723  df-clel 2809  df-v 3475  df-in 3955  df-ss 3965  df-pred 6300
This theorem is referenced by:  preddowncl  6333  wfrlem8OLD  8322
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