- // Set up the improvement variable, which is the difference between the current
- // static evaluation and the previous static evaluation at our turn (if we were
- // in check at our previous move we look at the move prior to it). The improvement
- // margin and the improving flag are used in various pruning heuristics.
- improvement = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval
- : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval
- : 173;
- improving = improvement > 0;
+ // Set up the improving flag, which is true if current static evaluation is
+ // bigger than the previous static evaluation at our turn (if we were in
+ // check at our previous move we look at static evaluaion at move prior to it
+ // and if we were in check at move prior to it flag is set to true) and is
+ // false otherwise. The improving flag is used in various pruning heuristics.
+ improving = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval > (ss-2)->staticEval
+ : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval > (ss-4)->staticEval
+ : true;