fact: Definition path_adjacent_cells (cells : seq cell) (source target : pt) (source_i target_i : nat) : option (seq (annotated_point * annotated_point)) := let source_cell := nth source_i cells dummy_cell in let target_cell := nth target_i cells dummy_cell in match common_vert_edge source_cell target_cell with | Some v => Some ((Apt source (source_i :: nil), Apt (vert_edge_midpoint v) (source_i :: target_i :: nil)) :: (Apt (vert_edge_midpoint v) (source_i :: target_i :: nil), Apt target (target_i :: nil)) :: nil) | None => None end.
imports: mathcomp(all_ssreflect) ZArith QArith List String OrderedType OrderedTypeEx FMapAVL