Chess - Programming - Move Ordering - Static Exchange Evaluation (SEE)

SEE stands for Static Exchange Evaluation.

• It is much more complicated than MVV/LVA, but allows for more accurate move ordering, and it allows for some captures to be discarded.

You cannot discard QxP in MVV/LVA, because it is very possible that the pawn is undefended, which would mean that QxP is a good move.

• Of course, if the pawn is defended, it is doubtful that anything significant is gained by searching this move at all.
• With a SEE, you can figure out if QxP is a losing capture, and if so, either order the capture so that it is searched last, or simply prune it.

How it works is that you apply a routine that resolves the captures, and then order moves by the amount of material that appears to be won.

• SEE allows bad capturing moves to be pruned very drastically, without many important captures being pruned out erroneously, and it improves move ordering.
• It also allows pruning out good captures, if they do not seem good enough.
  • If you are down a rook, a capture that wins a pawn is probably not worth trying in quiescent search.