Metamath Proof Explorer


Theorem incssnn0

Description: Transitivity induction of subsets, lemma for nacsfix . (Contributed by Stefan O'Rear, 4-Apr-2015)

Ref Expression
Assertion incssnn0 x0FxFx+1A0BAFAFB

Proof

Step Hyp Ref Expression
1 fveq2 a=AFa=FA
2 1 sseq2d a=AFAFaFAFA
3 2 imbi2d a=Ax0FxFx+1A0FAFax0FxFx+1A0FAFA
4 fveq2 a=bFa=Fb
5 4 sseq2d a=bFAFaFAFb
6 5 imbi2d a=bx0FxFx+1A0FAFax0FxFx+1A0FAFb
7 fveq2 a=b+1Fa=Fb+1
8 7 sseq2d a=b+1FAFaFAFb+1
9 8 imbi2d a=b+1x0FxFx+1A0FAFax0FxFx+1A0FAFb+1
10 fveq2 a=BFa=FB
11 10 sseq2d a=BFAFaFAFB
12 11 imbi2d a=Bx0FxFx+1A0FAFax0FxFx+1A0FAFB
13 ssid FAFA
14 13 2a1i Ax0FxFx+1A0FAFA
15 eluznn0 A0bAb0
16 15 ancoms bAA0b0
17 fveq2 x=bFx=Fb
18 fvoveq1 x=bFx+1=Fb+1
19 17 18 sseq12d x=bFxFx+1FbFb+1
20 19 rspcv b0x0FxFx+1FbFb+1
21 16 20 syl bAA0x0FxFx+1FbFb+1
22 21 expimpd bAA0x0FxFx+1FbFb+1
23 22 ancomsd bAx0FxFx+1A0FbFb+1
24 sstr2 FAFbFbFb+1FAFb+1
25 24 com12 FbFb+1FAFbFAFb+1
26 23 25 syl6 bAx0FxFx+1A0FAFbFAFb+1
27 26 a2d bAx0FxFx+1A0FAFbx0FxFx+1A0FAFb+1
28 3 6 9 12 14 27 uzind4 BAx0FxFx+1A0FAFB
29 28 com12 x0FxFx+1A0BAFAFB
30 29 3impia x0FxFx+1A0BAFAFB