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 x 0 F x F x + 1 A 0 B A F A F B

Proof

Step Hyp Ref Expression
1 fveq2 a = A F a = F A
2 1 sseq2d a = A F A F a F A F A
3 2 imbi2d a = A x 0 F x F x + 1 A 0 F A F a x 0 F x F x + 1 A 0 F A F A
4 fveq2 a = b F a = F b
5 4 sseq2d a = b F A F a F A F b
6 5 imbi2d a = b x 0 F x F x + 1 A 0 F A F a x 0 F x F x + 1 A 0 F A F b
7 fveq2 a = b + 1 F a = F b + 1
8 7 sseq2d a = b + 1 F A F a F A F b + 1
9 8 imbi2d a = b + 1 x 0 F x F x + 1 A 0 F A F a x 0 F x F x + 1 A 0 F A F b + 1
10 fveq2 a = B F a = F B
11 10 sseq2d a = B F A F a F A F B
12 11 imbi2d a = B x 0 F x F x + 1 A 0 F A F a x 0 F x F x + 1 A 0 F A F B
13 ssid F A F A
14 13 2a1i A x 0 F x F x + 1 A 0 F A F A
15 eluznn0 A 0 b A b 0
16 15 ancoms b A A 0 b 0
17 fveq2 x = b F x = F b
18 fvoveq1 x = b F x + 1 = F b + 1
19 17 18 sseq12d x = b F x F x + 1 F b F b + 1
20 19 rspcv b 0 x 0 F x F x + 1 F b F b + 1
21 16 20 syl b A A 0 x 0 F x F x + 1 F b F b + 1
22 21 expimpd b A A 0 x 0 F x F x + 1 F b F b + 1
23 22 ancomsd b A x 0 F x F x + 1 A 0 F b F b + 1
24 sstr2 F A F b F b F b + 1 F A F b + 1
25 24 com12 F b F b + 1 F A F b F A F b + 1
26 23 25 syl6 b A x 0 F x F x + 1 A 0 F A F b F A F b + 1
27 26 a2d b A x 0 F x F x + 1 A 0 F A F b x 0 F x F x + 1 A 0 F A F b + 1
28 3 6 9 12 14 27 uzind4 B A x 0 F x F x + 1 A 0 F A F B
29 28 com12 x 0 F x F x + 1 A 0 B A F A F B
30 29 3impia x 0 F x F x + 1 A 0 B A F A F B