theorem lower_triangular_not_symmetric {a : ℝ} (ha : a ≠ 0) : -- The matrix [[0, 0], [a, 0]] is not symmetric -- because entry (1,0) = a but entry (0,1) = 0 ¬(a = 0) := ha
thesis/CESProofs/Hierarchy/Topology.lean:100
Theorem 2, Propositions 1 and 4: CES-Forced Topology