∀ {w : ℕ} (lw lstart : ℕ) (lexpr : Std.Tactic.BVDecide.BVExpr lw) (rw rstart : ℕ)
  (rexpr : Std.Tactic.BVDecide.BVExpr rw),
  ¬(lw = rw ∧ lstart = rstart) →
    ¬Std.Tactic.BVDecide.BVExpr.extract lstart w lexpr = Std.Tactic.BVDecide.BVExpr.extract rstart w rexpr