Theorem nssss 4924

Description: Negation of subclass relationship. Compare nss 3663. (Contributed by NM, 30-Jun-2004.) (Proof shortened by Andrew Salmon, 25-Jul-2011.)

Assertion

Ref	Expression
nssss	|- ( -. A C_ B <-> E. x ( x C_ A /\ -. x C_ B ) )

Distinct variable groups:   x, A   x, B

Proof of Theorem nssss

Step	Hyp	Ref	Expression
1		exanali 1786	. . 3 |- ( E. x ( x C_ A /\ -. x C_ B ) <-> -. A. x ( x C_ A -> x C_ B ) )
2		ssextss 4922	. . 3 |- ( A C_ B <-> A. x ( x C_ A -> x C_ B ) )
3	1, 2	xchbinxr 325	. 2 |- ( E. x ( x C_ A /\ -. x C_ B ) <-> -. A C_ B )
4	3	bicomi 214	1 |- ( -. A C_ B <-> E. x ( x C_ A /\ -. x C_ B ) )

Syntax hints:   -. wn 3   -> wi 4   <-> wb 196   /\ wa 384   A.wal 1481   E.wex 1704   C_ wss 3574

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-nul 4789  ax-pr 4906

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-v 3202  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-nul 3916  df-pw 4160  df-sn 4178  df-pr 4180

This theorem is referenced by: (None)