Theorem nn0ssxnn0 9467

Description: The standard nonnegative integers are a subset of the extended nonnegative integers. (Contributed by AV, 10-Dec-2020.)

Assertion

Ref	Expression
nn0ssxnn0	|- NN0 C_ NN0*

Proof of Theorem nn0ssxnn0

Step	Hyp	Ref	Expression
1		ssun1 3370	. 2 |- NN0 C_ ( NN0 u. { +oo } )
2		df-xnn0 9465	. 2 |- NN0* = ( NN0 u. { +oo } )
3	1, 2	sseqtrri 3262	1 |- NN0 C_ NN0*

Syntax hints:   u. cun 3198   C_ wss 3200   {csn 3669   +oocpnf 8210   NN0cn0 9401  NN0*cxnn0 9464

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-un 3204  df-in 3206  df-ss 3213  df-xnn0 9465

This theorem is referenced by:  nn0xnn0  9468  0xnn0  9470  nn0xnn0d  9473  nninfctlemfo  12610