-/// MovePicker::go_next_phase() generates, scores and sorts the next bunch
-/// of moves when there are no more moves to try for the current phase.
+/// score() assign a numerical value to each move in a move list. The moves with
+/// highest values will be picked first.
+template<>
+void MovePicker::score<CAPTURES>() {
+ // Winning and equal captures in the main search are ordered by MVV.
+ // Suprisingly, this appears to perform slightly better than SEE based
+ // move ordering. The reason is probably that in a position with a winning
+ // capture, capturing a valuable (but sufficiently defended) piece
+ // first usually doesn't hurt. The opponent will have to recapture, and
+ // the hanging piece will still be hanging (except in the unusual cases
+ // where it is possible to recapture with the hanging piece). Exchanging
+ // big pieces before capturing a hanging piece probably helps to reduce
+ // the subtree size.
+ // In main search we want to push captures with negative SEE values to the
+ // badCaptures[] array, but instead of doing it now we delay until the move
+ // has been picked up in pick_move_from_list(). This way we save some SEE
+ // calls in case we get a cutoff.
+ for (auto& m : *this)
+ m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ - 200 * relative_rank(pos.side_to_move(), to_sq(m));
+}