Theorem bj-findes 16116

Description: Principle of induction, using explicit substitutions. Constructive proof (from CZF). See the comment of bj-findis 16114 for explanations. From this version, it is easy to prove findes 4669. (Contributed by BJ, 21-Nov-2019.) (Proof modification is discouraged.)

Assertion

Ref	Expression
bj-findes	|- ( ( [. (/) / x ]. ph /\ A. x e. om ( ph -> [. suc x / x ]. ph ) ) -> A. x e. om ph )

Proof of Theorem bj-findes

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		nfv 1552	. . . 4 |- F/ y ph
2		nfv 1552	. . . 4 |- F/ y [. suc x / x ]. ph
3	1, 2	nfim 1596	. . 3 |- F/ y ( ph -> [. suc x / x ]. ph )
4		nfs1v 1968	. . . 4 |- F/ x [ y / x ] ph
5		nfsbc1v 3024	. . . 4 |- F/ x [. suc y / x ]. ph
6	4, 5	nfim 1596	. . 3 |- F/ x ( [ y / x ] ph -> [. suc y / x ]. ph )
7		sbequ12 1795	. . . 4 |- ( x = y -> ( ph <-> [ y / x ] ph ) )
8		suceq 4467	. . . . 5 |- ( x = y -> suc x = suc y )
9	8	sbceq1d 3010	. . . 4 |- ( x = y -> ( [. suc x / x ]. ph <-> [. suc y / x ]. ph ) )
10	7, 9	imbi12d 234	. . 3 |- ( x = y -> ( ( ph -> [. suc x / x ]. ph ) <-> ( [ y / x ] ph -> [. suc y / x ]. ph ) ) )
11	3, 6, 10	cbvral 2738	. 2 |- ( A. x e. om ( ph -> [. suc x / x ]. ph ) <-> A. y e. om ( [ y / x ] ph -> [. suc y / x ]. ph ) )
12		nfsbc1v 3024	. . 3 |- F/ x [. (/) / x ]. ph
13		sbceq1a 3015	. . . 4 |- ( x = (/) -> ( ph <-> [. (/) / x ]. ph ) )
14	13	biimprd 158	. . 3 |- ( x = (/) -> ( [. (/) / x ]. ph -> ph ) )
15		sbequ1 1792	. . 3 |- ( x = y -> ( ph -> [ y / x ] ph ) )
16		sbceq1a 3015	. . . 4 |- ( x = suc y -> ( ph <-> [. suc y / x ]. ph ) )
17	16	biimprd 158	. . 3 |- ( x = suc y -> ( [. suc y / x ]. ph -> ph ) )
18	12, 4, 5, 14, 15, 17	bj-findis 16114	. 2 |- ( ( [. (/) / x ]. ph /\ A. y e. om ( [ y / x ] ph -> [. suc y / x ]. ph ) ) -> A. x e. om ph )
19	11, 18	sylan2b 287	1 |- ( ( [. (/) / x ]. ph /\ A. x e. om ( ph -> [. suc x / x ]. ph ) ) -> A. x e. om ph )

Syntax hints:   -> wi 4   /\ wa 104   = wceq 1373   [wsb 1786   A.wral 2486   [.wsbc 3005   (/)c0 3468   suc csuc 4430   omcom 4656

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 1471  ax-7 1472  ax-gen 1473  ax-ie1 1517  ax-ie2 1518  ax-8 1528  ax-10 1529  ax-11 1530  ax-i12 1531  ax-bndl 1533  ax-4 1534  ax-17 1550  ax-i9 1554  ax-ial 1558  ax-i5r 1559  ax-13 2180  ax-14 2181  ax-ext 2189  ax-nul 4186  ax-pr 4269  ax-un 4498  ax-setind 4603  ax-bd0 15948  ax-bdim 15949  ax-bdan 15950  ax-bdor 15951  ax-bdn 15952  ax-bdal 15953  ax-bdex 15954  ax-bdeq 15955  ax-bdel 15956  ax-bdsb 15957  ax-bdsep 16019  ax-infvn 16076

This theorem depends on definitions:  df-bi 117  df-tru 1376  df-fal 1379  df-nf 1485  df-sb 1787  df-clab 2194  df-cleq 2200  df-clel 2203  df-nfc 2339  df-ral 2491  df-rex 2492  df-rab 2495  df-v 2778  df-sbc 3006  df-dif 3176  df-un 3178  df-in 3180  df-ss 3187  df-nul 3469  df-sn 3649  df-pr 3650  df-uni 3865  df-int 3900  df-suc 4436  df-iom 4657  df-bdc 15976  df-bj-ind 16062

This theorem is referenced by: (None)