Inductive wishes_eq_horses := .

Lemma decode_val_uniq: (* Just not true any more, with Fragments *) forall ch b1 b2 v, v <> Vundef -> length b1 = size_chunk_nat ch -> length b2 = size_chunk_nat ch -> decode_val ch b1 = v -> decode_val ch b2 = v -> b1=b2.