Metamath Proof Explorer


Theorem clwwlknon2x

Description: The set of closed walks on vertex X of length 2 in a graph G as words over the set of vertices, definition of ClWWalksN expanded. (Contributed by Alexander van der Vekens, 19-Sep-2018) (Revised by AV, 25-Mar-2022)

Ref Expression
Hypotheses clwwlknon2.c C = ClWWalksNOn G
clwwlknon2x.v V = Vtx G
clwwlknon2x.e E = Edg G
Assertion clwwlknon2x X C 2 = w Word V | w = 2 w 0 w 1 E w 0 = X

Proof

Step Hyp Ref Expression
1 clwwlknon2.c C = ClWWalksNOn G
2 clwwlknon2x.v V = Vtx G
3 clwwlknon2x.e E = Edg G
4 1 clwwlknon2 X C 2 = w 2 ClWWalksN G | w 0 = X
5 clwwlkn2 w 2 ClWWalksN G w = 2 w Word Vtx G w 0 w 1 Edg G
6 5 anbi1i w 2 ClWWalksN G w 0 = X w = 2 w Word Vtx G w 0 w 1 Edg G w 0 = X
7 3anan12 w = 2 w Word Vtx G w 0 w 1 Edg G w Word Vtx G w = 2 w 0 w 1 Edg G
8 7 anbi1i w = 2 w Word Vtx G w 0 w 1 Edg G w 0 = X w Word Vtx G w = 2 w 0 w 1 Edg G w 0 = X
9 anass w Word Vtx G w = 2 w 0 w 1 Edg G w 0 = X w Word Vtx G w = 2 w 0 w 1 Edg G w 0 = X
10 2 eqcomi Vtx G = V
11 10 wrdeqi Word Vtx G = Word V
12 11 eleq2i w Word Vtx G w Word V
13 df-3an w = 2 w 0 w 1 E w 0 = X w = 2 w 0 w 1 E w 0 = X
14 3 eleq2i w 0 w 1 E w 0 w 1 Edg G
15 14 anbi2i w = 2 w 0 w 1 E w = 2 w 0 w 1 Edg G
16 15 anbi1i w = 2 w 0 w 1 E w 0 = X w = 2 w 0 w 1 Edg G w 0 = X
17 13 16 bitr2i w = 2 w 0 w 1 Edg G w 0 = X w = 2 w 0 w 1 E w 0 = X
18 12 17 anbi12i w Word Vtx G w = 2 w 0 w 1 Edg G w 0 = X w Word V w = 2 w 0 w 1 E w 0 = X
19 9 18 bitri w Word Vtx G w = 2 w 0 w 1 Edg G w 0 = X w Word V w = 2 w 0 w 1 E w 0 = X
20 8 19 bitri w = 2 w Word Vtx G w 0 w 1 Edg G w 0 = X w Word V w = 2 w 0 w 1 E w 0 = X
21 6 20 bitri w 2 ClWWalksN G w 0 = X w Word V w = 2 w 0 w 1 E w 0 = X
22 21 rabbia2 w 2 ClWWalksN G | w 0 = X = w Word V | w = 2 w 0 w 1 E w 0 = X
23 4 22 eqtri X C 2 = w Word V | w = 2 w 0 w 1 E w 0 = X