Theorem nssinpss 3487

Description: Negation of subclass expressed in terms of intersection and proper subclass. (Contributed by NM, 30-Jun-2004.) (Proof shortened by Andrew Salmon, 26-Jun-2011.)

Assertion

Ref	Expression
nssinpss	|- (-. A C_ B <-> (A i^i B) C. A)

Proof of Theorem nssinpss

Step	Hyp	Ref	Expression
1		inss1 3475	. . 3 |- (A i^i B) C_ A
2	1	biantrur 492	. 2 |- ((A i^i B) =/= A <-> ((A i^i B) C_ A /\ (A i^i B) =/= A))
3		df-ss 3259	. . 3 |- (A C_ B <-> (A i^i B) = A)
4	3	necon3bbii 2547	. 2 |- (-. A C_ B <-> (A i^i B) =/= A)
5		df-pss 3261	. 2 |- ((A i^i B) C. A <-> ((A i^i B) C_ A /\ (A i^i B) =/= A))
6	2, 4, 5	3bitr4i 268	1 |- (-. A C_ B <-> (A i^i B) C. A)

Syntax hints:  -. wn 3   <-> wb 176   /\ wa 358   =/= wne 2516   i^i cin 3208   C_ wss 3257   C. wpss 3258

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

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-ss 3259  df-pss 3261

This theorem is referenced by: (None)