377theorem square_loop_closed {D : ℕ} (j k : Fin D) : 378 is_closed (square_loop j k) := by
proof body
Term-mode proof.
379 intro axis 380 simp [square_loop, winding_number, step_displacement] 381 split <;> split <;> simp 382 383/-- The square loop can be decomposed into two cancelling pairs 384 when j = k (trivial case). When j ≠ k, the loop is genuinely 385 2-dimensional — it bounds a square face of the lattice. -/
depends on (14)
Lean names referenced from this declaration's body.