Is Naum 4 a serious challenge for Rybka

[M ANSARI]

N4 has a very serious flaw in its search ... it is a very inefficient searcher in some critical positions when compared to Rybka 3. I am doing a match of an 8 core N4 against 1 single core Rybka 3 @ Ghz on one of my Octa's at 5 min + 1sec time controls with neutral 7move HS book. The only modification I did on the single core Rybka 3 was to change the contempt from default 15 to 0. I had expected an 8 core N4 to score around 60% to 65% against R3 single core ... but so far after 162 games R3 single core leads 51% to 49%. I had expected N4 to win easily because at fast time controls the short time frame usually helps an Octa against a single core. Looking at the games it is painfully obvious that even with 1 core ... Rybka 3 will outsearch N4 in many positions. N4 is notoriously bad at searching possibilities of pawns advancing ... in one game I was watching R3 single core was showing a -4 evaluation due to such a position ... and it took N4 3 or 4 moves before it changed its +.30 evaluation to a -3.00+ evaluation. I will try also 200 games at R3 single core with the default 15 contempt and see what happens.