TCEC openings

[jdart]

I think there is a difference between, on the one hand, balanced openings where there really are no winning chances, or where in practice there are many short draws (for example, because one side can force a repetition), and on the other hand, openings that lead to a "dynamically" balanced position where the two sides each have chances but the game is still likely to be long and complex. In both cases you might have a close to zero eval. But the second class can still give you interesting games.

--Jon

[lkaufman]

Starting from the same opening position the chances are different for a mainly tactical monster like Stockfish and for a mainly positional monster like Komodo. A tactical engine finds a good continuation easier in an unbalanced position than in a balanced position and vice verse a positional engine does. So in my opinion a really good arrange is 50% balanced and 50% unbalanced opening position played with reversed color.

I guess it depends on the nature of the imbalance. If White is ahead by the bishop pair (for example) in an otherwise balanced position, it might be close enough to the win/draw line to show which program is stronger in normal positions. I did some tests (using the Monte Carlo feature of Fritz 15) to try to determine how much of an advantage constitutes the dividing line between win and draw, by removing various pawns from the initial position and comparing wins for the stronger side with draws plus wins for the weaker side, looking for near-equality. I tried various search depths to look for trends. Overall, the most appropriate position was the initial position with the b2 pawn removed. At almost every depth tested (from 8 to 15 ply), Black won very close to half the games, usually in the 49 to 51% range. Removing f2 or g2 gave Black clear superiority, while most of the other White pawns removal left Black below 50% wins. Frankly, I'm a bit surprised at this result. I would have thought that removing any non-edge pawn would be enough to give Black a won game, but based on the above this may not be true. Chess seems to offer the weaker side more drawing chances than most of us believe.

[JJJ]

That's means chess is a draw even with one pawn less if the pawn don't compromise king safety

[hgm]

This fits reasonably with the report I saw several years ago on Rybka forum, where someone tested all possible Pawn-odds positions in Rybka self-play. IIRC scores of around 73% were reported there.

It might depend on the engine a bit,and particular its skill in the opening; with Fairy-Max I usually see a 68% advantage as a result of deleting a Pawn (but I always average over both colors, so that does not include any first-move advantage). It also seems to not matter very much which Pawn I delete there, probably because Fairy-Max does not have any skill, and therefore cannot exploit specific positional opening advantages very well, but allows these to evaporate.

BTW, I don't think that the issue with f2 deletion is King Safety, as the King usually doesn't keep camp on e1 very long. It is more that all other Pawn deletions offer some compensation by accelerating development.

[Lyudmil Tsvetkov]

Starting from the same opening position the chances are different for a mainly tactical monster like Stockfish and for a mainly positional monster like Komodo. A tactical engine finds a good continuation easier in an unbalanced position than in a balanced position and vice verse a positional engine does. So in my opinion a really good arrange is 50% balanced and 50% unbalanced opening position played with reversed color.

I guess it depends on the nature of the imbalance. If White is ahead by the bishop pair (for example) in an otherwise balanced position, it might be close enough to the win/draw line to show which program is stronger in normal positions. I did some tests (using the Monte Carlo feature of Fritz 15) to try to determine how much of an advantage constitutes the dividing line between win and draw, by removing various pawns from the initial position and comparing wins for the stronger side with draws plus wins for the weaker side, looking for near-equality. I tried various search depths to look for trends. Overall, the most appropriate position was the initial position with the b2 pawn removed. At almost every depth tested (from 8 to 15 ply), Black won very close to half the games, usually in the 49 to 51% range. Removing f2 or g2 gave Black clear superiority, while most of the other White pawns removal left Black below 50% wins. Frankly, I'm a bit surprised at this result. I would have thought that removing any non-edge pawn would be enough to give Black a won game, but based on the above this may not be true. Chess seems to offer the weaker side more drawing chances than most of us believe.

That is because in most similar positions there is omly one, or maybe 2 plausible first winning moves.

I have been trying some handicap games with Komodo playing white while removing f2,e2,d2 pawns, etc., and usually in omly 1 or 2 black first moves/setups on white's first choice a clear advantage for black will arise, otherwise game will be slightly better for black, drawish, or even white might take the edge.

If Monte Carlo of Fritz 15 implies some kind of random picking of moves, that might easily explain the result.

To my knowledge, all single pawn handicaps, except possibly white h2 pawn, are won for the handicap-taker.

[hgm]

To my knowledge, all single pawn handicaps, except possibly white h2 pawn, are won for the handicap-taker.

Spoke the oracle...

[Laskos]

This fits reasonably with the report I saw several years ago on Rybka forum, where someone tested all possible Pawn-odds positions in Rybka self-play. IIRC scores of around 73% were reported there.

It might depend on the engine a bit,and particular its skill in the opening; with Fairy-Max I usually see a 68% advantage as a result of deleting a Pawn (but I always average over both colors, so that does not include any first-move advantage). It also seems to not matter very much which Pawn I delete there, probably because Fairy-Max does not have any skill, and therefore cannot exploit specific positional opening advantages very well, but allows these to evaporate.

BTW, I don't think that the issue with f2 deletion is King Safety, as the King usually doesn't keep camp on e1 very long. It is more that all other Pawn deletions offer some compensation by accelerating development.

It does depend on the skill. Komodo gets as Black roughly 77% from b2 pawn handicap at 5''+0.05'' self-play. Some care must be taken describing the results, as there are White wins too. Roughly 60% Black wins, 35% draws, 5% White wins in this case. Already a bit different from what Larry gets with fast Rybka. At longer time controls the Black performance increases further.

[hgm]

Does Komodo randomize enough to consider the games independent?

[Laskos]

Does Komodo randomize enough to consider the games independent?

4 openings, engine on 2 threads.

[lkaufman]

This fits reasonably with the report I saw several years ago on Rybka forum, where someone tested all possible Pawn-odds positions in Rybka self-play. IIRC scores of around 73% were reported there.

It might depend on the engine a bit,and particular its skill in the opening; with Fairy-Max I usually see a 68% advantage as a result of deleting a Pawn (but I always average over both colors, so that does not include any first-move advantage). It also seems to not matter very much which Pawn I delete there, probably because Fairy-Max does not have any skill, and therefore cannot exploit specific positional opening advantages very well, but allows these to evaporate.

BTW, I don't think that the issue with f2 deletion is King Safety, as the King usually doesn't keep camp on e1 very long. It is more that all other Pawn deletions offer some compensation by accelerating development.

It does depend on the skill. Komodo gets as Black roughly 77% from b2 pawn handicap at 5''+0.05'' self-play. Some care must be taken describing the results, as there are White wins too. Roughly 60% Black wins, 35% draws, 5% White wins in this case. Already a bit different from what Larry gets with fast Rybka. At longer time controls the Black performance increases further.

Your results agree more or less with my opinion as a grandmaster but as you say not so well with my test results using Fritz 15 MC. Perhaps it is just due to higher level of technique in Komodo, but another factor might be that both sides in your test used Contempt (unless you set them to zero), which would make for fewer draws and thus help the stronger side. Perhaps you might try removing c2, which is (I think) the best choice for White to remove other than the two edge pawns. My personal opinion is that removing any of the six non-edge pawns of White should be enough to give Black a theoretically won game, but not the two edge pawns. So I differ from Lyudmil only on the a2 pawn removal.