apply Eq.symm
V : Sort u_1
G : SerreGraph V
A B C : V
p✝ p : Path A B
p' : Path B A := inverse p
pinv : p = inverse p'
⊢ last (inverse p') = first p'
case h
V : Sort u_1
G : SerreGraph V
A B C : V
p✝ p : Path A B
p' : Path B A := inverse p
pinv : p = inverse p'
⊢ first p' = last (inverse p')