Theorem ssinss1 3392

Description: Intersection preserves subclass relationship. (Contributed by NM, 14-Sep-1999.)

Assertion

Ref	Expression
ssinss1	|- ( A C_ C -> ( A i^i B ) C_ C )

Proof of Theorem ssinss1

Step	Hyp	Ref	Expression
1		inss1 3383	. 2 |- ( A i^i B ) C_ A
2		sstr2 3190	. 2 |- ( ( A i^i B ) C_ A -> ( A C_ C -> ( A i^i B ) C_ C ) )
3	1, 2	ax-mp 5	1 |- ( A C_ C -> ( A i^i B ) C_ C )

Syntax hints:   -> wi 4   i^i cin 3156   C_ wss 3157

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-v 2765  df-in 3163  df-ss 3170

This theorem is referenced by:  inss  3393  insubm  13117  distop  14321  ntrin  14360  innei  14399  txcnp  14507