Theorem unissd 3917

Description: Subclass relationship for subclass union. Deduction form of uniss 3914. (Contributed by David Moews, 1-May-2017.)

Hypothesis

Ref	Expression
unissd.1	|- ( ph -> A C_ B )

Assertion

Ref	Expression
unissd	|- ( ph -> U. A C_ U. B )

Proof of Theorem unissd

Step	Hyp	Ref	Expression
1		unissd.1	. 2 |- ( ph -> A C_ B )
2		uniss 3914	. 2 |- ( A C_ B -> U. A C_ U. B )
3	1, 2	syl 14	1 |- ( ph -> U. A C_ U. B )

Syntax hints:   -> wi 4   C_ wss 3200   U.cuni 3893

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 716  ax-5 1495  ax-7 1496  ax-gen 1497  ax-ie1 1541  ax-ie2 1542  ax-8 1552  ax-10 1553  ax-11 1554  ax-i12 1555  ax-bndl 1557  ax-4 1558  ax-17 1574  ax-i9 1578  ax-ial 1582  ax-i5r 1583  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-tru 1400  df-nf 1509  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2363  df-v 2804  df-in 3206  df-ss 3213  df-uni 3894

This theorem is referenced by:  iotanul  5302  tfrlemibfn  6493  tfrlemiubacc  6495  tfr1onlemssrecs  6504  tfr1onlembfn  6509  tfr1onlemubacc  6511  tfrcllemssrecs  6517  tfrcllembfn  6522  tfrcllemubacc  6524  fiuni  7176  eltg3i  14779  unitg  14785  tgss  14786  ntrss  14842