Theorem bj-nn0suc 16680

Description: Proof of (biconditional form of) nn0suc 4708 from the core axioms of CZF. See also bj-nn0sucALT 16694. As a characterization of the elements of om, this could be labeled "elom". (Contributed by BJ, 19-Nov-2019.) (Proof modification is discouraged.)

Assertion

Ref	Expression
bj-nn0suc	|- ( A e. om <-> ( A = (/) \/ E. x e. om A = suc x ) )

Distinct variable group:   x, A

Proof of Theorem bj-nn0suc

Step	Hyp	Ref	Expression
1		bj-nn0suc0 16666	. . 3 |- ( A e. om -> ( A = (/) \/ E. x e. A A = suc x ) )
2		bj-omtrans 16672	. . . . 5 |- ( A e. om -> A C_ om )
3		ssrexv 3293	. . . . 5 |- ( A C_ om -> ( E. x e. A A = suc x -> E. x e. om A = suc x ) )
4	2, 3	syl 14	. . . 4 |- ( A e. om -> ( E. x e. A A = suc x -> E. x e. om A = suc x ) )
5	4	orim2d 796	. . 3 |- ( A e. om -> ( ( A = (/) \/ E. x e. A A = suc x ) -> ( A = (/) \/ E. x e. om A = suc x ) ) )
6	1, 5	mpd 13	. 2 |- ( A e. om -> ( A = (/) \/ E. x e. om A = suc x ) )
7		peano1 4698	. . . 4 |- (/) e. om
8		eleq1 2294	. . . 4 |- ( A = (/) -> ( A e. om <-> (/) e. om ) )
9	7, 8	mpbiri 168	. . 3 |- ( A = (/) -> A e. om )
10		bj-peano2 16655	. . . . 5 |- ( x e. om -> suc x e. om )
11		eleq1a 2303	. . . . . 6 |- ( suc x e. om -> ( A = suc x -> A e. om ) )
12	11	imp 124	. . . . 5 |- ( ( suc x e. om /\ A = suc x ) -> A e. om )
13	10, 12	sylan 283	. . . 4 |- ( ( x e. om /\ A = suc x ) -> A e. om )
14	13	rexlimiva 2646	. . 3 |- ( E. x e. om A = suc x -> A e. om )
15	9, 14	jaoi 724	. 2 |- ( ( A = (/) \/ E. x e. om A = suc x ) -> A e. om )
16	6, 15	impbii 126	1 |- ( A e. om <-> ( A = (/) \/ E. x e. om A = suc x ) )

Syntax hints:   -> wi 4   <-> wb 105   \/ wo 716   = wceq 1398   e. wcel 2202   E.wrex 2512   C_ wss 3201   (/)c0 3496   suc csuc 4468   omcom 4694

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 619  ax-in2 620  ax-io 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-13 2204  ax-14 2205  ax-ext 2213  ax-nul 4220  ax-pr 4305  ax-un 4536  ax-bd0 16529  ax-bdim 16530  ax-bdan 16531  ax-bdor 16532  ax-bdn 16533  ax-bdal 16534  ax-bdex 16535  ax-bdeq 16536  ax-bdel 16537  ax-bdsb 16538  ax-bdsep 16600  ax-infvn 16657

This theorem depends on definitions:  df-bi 117  df-tru 1401  df-fal 1404  df-nf 1510  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2364  df-ral 2516  df-rex 2517  df-rab 2520  df-v 2805  df-dif 3203  df-un 3205  df-in 3207  df-ss 3214  df-nul 3497  df-sn 3679  df-pr 3680  df-uni 3899  df-int 3934  df-suc 4474  df-iom 4695  df-bdc 16557  df-bj-ind 16643

This theorem is referenced by:  bj-findis  16695