- // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
- // re-searched at full depth.
+ (ss+1)->distanceFromPv = ss->distanceFromPv + moveCount - 1;
+
+ // Step 16. Late moves reduction / extension (LMR, ~200 Elo)
+ // We use various heuristics for the sons of a node after the first son has
+ // been searched. In general we would like to reduce them, but there are many
+ // cases where we extend a son if it has good chances to be "interesting".