exact absurd hcntr.1 <| pivot_not_mem_path i j
case refl
m n : Nat
i : Fin m
j : Fin n
ha : ↑(Board.pivot i j) < (m + 1) * (n + 1) - 1
hcntr :
  Board.pivot i j ∈ Board.path i j ∧
    Fin.restrict (Board.pivot i j) (_ : ↑(Board.pivot i j) < (m + 1) * (n + 1) - 1) = Fin.restrict (Board.pivot i j) ha
⊢ False
no goals