- ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
-
- // We want to extend the TT move if it is much better then remaining ones.
- // To verify this we do a reduced search on all the other moves but the ttMove,
- // if result is lower then TT value minus a margin then we assume ttMove is the
- // only one playable. It is a kind of relaxed single reply extension.
- if ( depth >= 4 * OnePly
- && !excludedMove // do not allow recursive single-reply search
- && move == ttMove
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
+
+ // Singular extension search. We extend the TT move if its value is much better than
+ // its siblings. To verify this we do a reduced search on all the other moves but the
+ // ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
+ if ( depth >= 8 * OnePly
+ && tte
+ && move == tte->move()
+ && !excludedMove // Do not allow recursive single-reply search