fact: Definition update_open_cell (c : cell) (e : event) : seq cell * cell := let ps := left_pts c in if outgoing e is [::] then ([::], set_left_pts c [:: head dummy_pt ps, point e & behead ps]) else match opening_cells_aux (point e) (sort edge_below (outgoing e)) (low c) (high c) with | ([::], c') => ([::], c) | (c'::tlc', lc') => (set_left_pts c' (point e :: behead ps) :: tlc', lc') end.
imports: mathcomp(all_ssreflect) ZArith QArith List String OrderedType OrderedTypeEx FMapAVL