For a class C of binary linear codes, we write θC : (0, 1) → [0, 12 ] for the maximum-likelihood decoding threshold function of C, the function whose value at R ∈ (0, 1) is the largest bit-error rate p that codes in C can tolerate with a negligible probability of maximum-likelihood decoding error across a binary symmetric channel. We show that, if C is the class of cycle codes of graphs, then θ...