Theorem pwntru 4243

Description: A slight strengthening of pwtrufal 15934. (Contributed by Mario Carneiro and Jim Kingdon, 12-Sep-2023.)

Assertion

Ref	Expression
pwntru	|- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> A = (/) )

Proof of Theorem pwntru

Dummy variable x is distinct from all other variables.

Step	Hyp	Ref	Expression
1		simpr 110	. . . 4 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> A =/= { (/) } )
2	1	neneqd 2397	. . 3 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> -. A = { (/) } )
3		simpll 527	. . . . . 6 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> A C_ { (/) } )
4		simpl 109	. . . . . . . . . 10 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> A C_ { (/) } )
5	4	sselda 3193	. . . . . . . . 9 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> x e. { (/) } )
6		elsni 3651	. . . . . . . . 9 |- ( x e. { (/) } -> x = (/) )
7	5, 6	syl 14	. . . . . . . 8 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> x = (/) )
8		simpr 110	. . . . . . . 8 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> x e. A )
9	7, 8	eqeltrrd 2283	. . . . . . 7 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> (/) e. A )
10	9	snssd 3778	. . . . . 6 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> { (/) } C_ A )
11	3, 10	eqssd 3210	. . . . 5 |- ( ( ( A C_ { (/) } /\ A =/= { (/) } ) /\ x e. A ) -> A = { (/) } )
12	11	ex 115	. . . 4 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> ( x e. A -> A = { (/) } ) )
13	12	exlimdv 1842	. . 3 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> ( E. x x e. A -> A = { (/) } ) )
14	2, 13	mtod 665	. 2 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> -. E. x x e. A )
15		notm0 3481	. 2 |- ( -. E. x x e. A <-> A = (/) )
16	14, 15	sylib 122	1 |- ( ( A C_ { (/) } /\ A =/= { (/) } ) -> A = (/) )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 104   = wceq 1373   E.wex 1515   e. wcel 2176   =/= wne 2376   C_ wss 3166   (/)c0 3460   {csn 3633

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-in1 615  ax-in2 616  ax-io 711  ax-5 1470  ax-7 1471  ax-gen 1472  ax-ie1 1516  ax-ie2 1517  ax-8 1527  ax-10 1528  ax-11 1529  ax-i12 1530  ax-bndl 1532  ax-4 1533  ax-17 1549  ax-i9 1553  ax-ial 1557  ax-i5r 1558  ax-ext 2187

This theorem depends on definitions:  df-bi 117  df-tru 1376  df-fal 1379  df-nf 1484  df-sb 1786  df-clab 2192  df-cleq 2198  df-clel 2201  df-nfc 2337  df-ne 2377  df-v 2774  df-dif 3168  df-in 3172  df-ss 3179  df-nul 3461  df-sn 3639

This theorem is referenced by:  exmid1dc  4244  exmid1stab  4252