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Up Topic Rybka Support & Discussion / Rybka Discussion / Horizon effects in Rybka 4 search.
- By rocket (***) [se] Date 2014-01-08 15:41
Rybka 4 time and time again exhibit ugly horizon effects in the search, coupled with an overall weaker tactics spotter. How can one explain both these deffiencys, in light of 30-40 elo improvements? Though R3 and R4 are almost tied at SDf rating list)

The latest display of this unreliable search occured in TCEC stage 3 in 2013, opposite Naum. Rybka 4 has a2 in it's initial winning line, it's -3 for black, easily winning. Yet it  Switches to Rd8 which leads to a draw. R3 knows with certainty that this move is bad. R4 evaluates them to be similiar, favouring Rd8?? in the end.

Other horizon misshaps have been overlooking forced draw continuations (once again in a winning position) or being completley blind to piece sacrifices (the latter is rarer but does pop up from time to time). Once again, checking with rybka 3 it's a wake and alert at all times.

The only theory I have for this is that Vas made the search more selective in R4 and improved the depth, at the cost of these ugly side effects
Up Topic Rybka Support & Discussion / Rybka Discussion / Horizon effects in Rybka 4 search.

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