Noise Bug

[Henk]

Found a bug yesterday. Must have been there for months in Skippers source code. (See simplified code)

Code: Select all

            saveLB : Original lb (= lowerbound)
            if (essentialMove)
            {
                 int noise =  (lb - Noise >= saveLB  && plyCount == 0 && mvCount > 1) ? Noise : 0;
                  var researchResult = Search (depth - R,  -(ub - noise), -(lb - noise), mv);
                  score = -(researchResult.value + noise);  
            }
 

Bug is that Noise can be negative too. I still don't understand it. If I make Noise only positive bug will be gone if I am right
Now ub - Noise >= ub if Noise negative.

[Henk]

Probably bug appears if research does not stay within range <saveLB, ub> where saveLB = unmodified lb

This is all about preventing same games are played over and over again. A workaround is to add noise to evaluation only.

[Henk]

I doubt code posted is correct. So I chose for workaround. Less worries.