simp [inverse]
V : Sort u_1
C : CombinatorialTwoComplex V
u v : V
p✝ q r p : Path u v
⊢ NullHomotopy (append (append p (inverse p)) (inverse nil))
V : Sort u_1
C : CombinatorialTwoComplex V
u v : V
p✝ q r p : Path u v
⊢ NullHomotopy (append p (inverse p))