Theorem snelpwi 4116

Description: A singleton of a set belongs to the power class of a class containing the set. (Contributed by Alan Sare, 25-Aug-2011.)

Assertion

Ref	Expression
snelpwi	|- (A e. B -> {A} e. ~PB)

Proof of Theorem snelpwi

Step	Hyp	Ref	Expression
1		snssi 3852	. 2 |- (A e. B -> {A} C_ B)
2		snex 4111	. . 3 |- {A} e. _V
3	2	elpw 3728	. 2 |- ({A} e. ~PB <-> {A} C_ B)
4	1, 3	sylibr 203	1 |- (A e. B -> {A} e. ~PB)

Syntax hints:   -> wi 4   e. wcel 1710   C_ wss 3257  ~Pcpw 3722  {csn 3737

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334  ax-nin 4078  ax-sn 4087

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-ne 2518  df-v 2861  df-nin 3211  df-compl 3212  df-in 3213  df-un 3214  df-dif 3215  df-ss 3259  df-nul 3551  df-pw 3724  df-sn 3741

This theorem is referenced by:  unipw  4117