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Parent - - By rocket (****) Date 2018-03-30 11:09
Could be an issue with the material values. If you cranked up the values for connected passers, it should give a positive evaluation for the sacrifice. Problem is that it would probably play weaker overall and overestimate connected passers in other games. That's the main difficulty in engine work.
Parent - - By Lyudmil Tsvetkov (**) Date 2018-03-31 08:19
No, there is no issue, this is mainline SF, you see its score drop from + 100 to -100, so it simply misunderstands the position.
I have looked at around 100 similar examples, before formulating the concept of 'spearhead connected passers'.
Not much has been left to chance.
There might be slight issues with particular positions, but the concept should hold.
Parent - - By rocket (****) Date 2018-03-31 13:01
That's what I mean is the issue. The depth of its search should make it understand the sacrifice if the tuning of the weights are optimized.
Parent - - By Lyudmil Tsvetkov (**) Date 2018-04-01 11:09
Problem is, tuning is not always possible, even if perfectly tuned.
In the present case, you need new weights, the so-called 'spearhead connected passer'.
I doubt very much any combination of existing terms could substitute for it.
Parent - - By rocket (****) Date 2018-04-01 13:31
You don't need a new eval term. It's connected passed pawns, which are already implemented. The horizon effect occurs due to the material imbalance. Precise tuning of the weights optimizes an engines evaluation of those positions before the search solves it.
Parent - - By MarshallArts (***) Date 2018-04-01 21:39
They're connected AND protected spearhead passers, meaning they're also supported by the chains behind them.
That's more than simple connected passers.

Parent - - By Lyudmil Tsvetkov (**) Date 2018-05-29 18:09
As part of a free promotion, running for a couple of days, my latest book, 'Practical Mates', is offered for free.
Download it here:
500 mate problems, ranging from 1 to 5 moves.
You will get much better after reading it, of course.
If interested, spread the word about it.
Parent - - By Lyudmil Tsvetkov (**) Date 2018-05-31 17:42
2 more days to go for the free promotion of my latest book, 'Practical Mates'.
Download it here to get stronger at checkmate pattern recognition and at chess:
Parent - By Antares (****) Date 2018-05-31 18:11
Is the Marshall covered in it as well? According to you Be3 must be a mate in 17 or so?!
Up Topic The Rybka Lounge / Computer Chess / The Secret of Chess
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