Metamath Proof Explorer


Theorem wlkonprop

Description: Properties of a walk between two vertices. (Contributed by Alexander van der Vekens, 12-Dec-2017) (Revised by AV, 31-Dec-2020) (Proof shortened by AV, 16-Jan-2021)

Ref Expression
Hypothesis wlkson.v V = Vtx G
Assertion wlkonprop F A WalksOn G B P G V A V B V F V P V F Walks G P P 0 = A P F = B

Proof

Step Hyp Ref Expression
1 wlkson.v V = Vtx G
2 1 fvexi V V
3 df-wlkson WalksOn = g V a Vtx g , b Vtx g f p | f Walks g p p 0 = a p f = b
4 1 wlkson A V B V A WalksOn G B = f p | f Walks G p p 0 = A p f = B
5 4 3adant1 G V A V B V A WalksOn G B = f p | f Walks G p p 0 = A p f = B
6 fveq2 g = G Vtx g = Vtx G
7 6 1 eqtr4di g = G Vtx g = V
8 fveq2 g = G Walks g = Walks G
9 8 breqd g = G f Walks g p f Walks G p
10 9 3anbi1d g = G f Walks g p p 0 = a p f = b f Walks G p p 0 = a p f = b
11 3 5 7 7 10 bropfvvvv V V V V F A WalksOn G B P G V A V B V F V P V
12 2 2 11 mp2an F A WalksOn G B P G V A V B V F V P V
13 3anass G V A V B V G V A V B V
14 13 anbi1i G V A V B V F V P V G V A V B V F V P V
15 df-3an G V A V B V F V P V G V A V B V F V P V
16 14 15 bitr4i G V A V B V F V P V G V A V B V F V P V
17 12 16 sylibr F A WalksOn G B P G V A V B V F V P V
18 1 iswlkon A V B V F V P V F A WalksOn G B P F Walks G P P 0 = A P F = B
19 18 3adantl1 G V A V B V F V P V F A WalksOn G B P F Walks G P P 0 = A P F = B
20 19 biimpd G V A V B V F V P V F A WalksOn G B P F Walks G P P 0 = A P F = B
21 20 imdistani G V A V B V F V P V F A WalksOn G B P G V A V B V F V P V F Walks G P P 0 = A P F = B
22 17 21 mpancom F A WalksOn G B P G V A V B V F V P V F Walks G P P 0 = A P F = B
23 df-3an G V A V B V F V P V F Walks G P P 0 = A P F = B G V A V B V F V P V F Walks G P P 0 = A P F = B
24 22 23 sylibr F A WalksOn G B P G V A V B V F V P V F Walks G P P 0 = A P F = B