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Theorem ssinss1 3273
 Description: Intersection preserves subclass relationship. (Contributed by NM, 14-Sep-1999.)
Assertion
Ref Expression
ssinss1 (𝐴𝐶 → (𝐴𝐵) ⊆ 𝐶)

Proof of Theorem ssinss1
StepHypRef Expression
1 inss1 3264 . 2 (𝐴𝐵) ⊆ 𝐴
2 sstr2 3072 . 2 ((𝐴𝐵) ⊆ 𝐴 → (𝐴𝐶 → (𝐴𝐵) ⊆ 𝐶))
31, 2ax-mp 5 1 (𝐴𝐶 → (𝐴𝐵) ⊆ 𝐶)
 Colors of variables: wff set class Syntax hints:   → wi 4   ∩ cin 3038   ⊆ wss 3039 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 681  ax-5 1406  ax-7 1407  ax-gen 1408  ax-ie1 1452  ax-ie2 1453  ax-8 1465  ax-10 1466  ax-11 1467  ax-i12 1468  ax-bndl 1469  ax-4 1470  ax-17 1489  ax-i9 1493  ax-ial 1497  ax-i5r 1498  ax-ext 2097 This theorem depends on definitions:  df-bi 116  df-tru 1317  df-nf 1420  df-sb 1719  df-clab 2102  df-cleq 2108  df-clel 2111  df-nfc 2245  df-v 2660  df-in 3045  df-ss 3052 This theorem is referenced by:  inss  3274  distop  12149  ntrin  12188  innei  12227  txcnp  12335
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