King opposition
Moderator: Ras
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kbhearn
- Posts: 411
- Joined: Thu Dec 30, 2010 4:48 am
Re: King opposition
Opposition is a very simplistic human rule with loads of exceptions. In the general case, it comes down to an easily recognisable special case of corresponding squares. Whether it's a good, bad, or pointless situation however requires further analysis. i.e. at some point you have to give up the opposition in order to flank your opponent. sometimes you want the opposition at the start of your turn instead because you need the opposition after a needed pawn break. sometimes the opposition is pointless because there's nothing to outflank. it's easy to believe that merely looking for opposition in pawn endings you might just come up with noise as to recognising winning pawn endings faster (and playing them out should be trivial with a hash table due to a low number of positions to examine).
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syzygy
- Posts: 5943
- Joined: Tue Feb 28, 2012 11:56 pm
Re: King opposition
Your "This makes no sense" seemed to refer to an observed decrease in Elo, i.e. to an effect on real games.bob wrote:I simply gave an example of where opposition is important. However, if you are going to analyze endgame positions, this will certainly be significant... In real games, not so much.syzygy wrote:You claimed recently that having or not having KPK knowledge in whatever form really did not matter in terms of Elo.bob wrote:This makes no sense. Opposition is critical in KPK, for example. If you don't know about opposition, you have practically no chance of winning when you should win, or drawing when you should (from losing side)...cetormenter wrote:The Stockfish team tried experimenting with this. Perhaps not enough effort was put into the idea but in the end the tests failed. Surprisingly it seems that NOT having the opposition did better than having it. However this probably was just statistical noise and one of the tests got lucky/unlucky.
http://tests.stockfishchess.org/tests/v ... 344346beea
http://tests.stockfishchess.org/tests/v ... 344346beec
Anyway, Stockfish has a bitbase for KPK.
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lucasart
- Posts: 3243
- Joined: Mon May 31, 2010 1:29 pm
- Full name: lucasart
Re: King opposition
Sorry I missed the second bugfix patch. Bonus was the wrong way around in the first patch.cetormenter wrote:Did you look at both of the links? The second one was a bug fix to fix exactly that issue. I believe the patch failed simply because there was too much weight given to this term. If one side had the opposition then it would be given ~15.5 CP (40 / 258) of an advantage. I believe like you said, that this idea is being applied too simplistically as there are many positions where you do not need to strive to gain the opposition. Also, this factor does not take into account the ability of the opponent to gain back the opposition. Through a series of pawn moves your opponent may be able to regain opposition and then take the game.
Yes, I completely agree that the weight is unreasonable. To give you an idea, the *optimized* value of a tempo in DiscoCheck is only 4cp. This may be extremely small, yet modifying this value by to either 2cp or 6cp was a measurable regression (1cp is not possible to measure with my testing resources).
After experimenting in a few different to refine the tempo value in pawn endgings in case of opposition, I've come to the conclusion that it was always useless or regressive. Case closed, as far as DiscoCheck is concerned. It does not mean the idea of opposition cannot work, but I don't think it can work in such a simplistic form. Really the concept of opposition is much too vague and is riddled with exceptions to be useful by itself in CC.
Theory and practice sometimes clash. And when that happens, theory loses. Every single time.
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bob
- Posts: 20943
- Joined: Mon Feb 27, 2006 7:30 pm
- Location: Birmingham, AL
Re: King opposition
It was intended to apply to chess, period. I certainly use it in my chess program to evaluate KPK properly...syzygy wrote:Your "This makes no sense" seemed to refer to an observed decrease in Elo, i.e. to an effect on real games.bob wrote:I simply gave an example of where opposition is important. However, if you are going to analyze endgame positions, this will certainly be significant... In real games, not so much.syzygy wrote:You claimed recently that having or not having KPK knowledge in whatever form really did not matter in terms of Elo.bob wrote:This makes no sense. Opposition is critical in KPK, for example. If you don't know about opposition, you have practically no chance of winning when you should win, or drawing when you should (from losing side)...cetormenter wrote:The Stockfish team tried experimenting with this. Perhaps not enough effort was put into the idea but in the end the tests failed. Surprisingly it seems that NOT having the opposition did better than having it. However this probably was just statistical noise and one of the tests got lucky/unlucky.
http://tests.stockfishchess.org/tests/v ... 344346beea
http://tests.stockfishchess.org/tests/v ... 344346beec
Anyway, Stockfish has a bitbase for KPK.
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bob
- Posts: 20943
- Joined: Mon Feb 27, 2006 7:30 pm
- Location: Birmingham, AL
Re: King opposition
It was intended to apply to chess, period. I certainly use it in my chess program to evaluate KPK properly...syzygy wrote:Your "This makes no sense" seemed to refer to an observed decrease in Elo, i.e. to an effect on real games.bob wrote:I simply gave an example of where opposition is important. However, if you are going to analyze endgame positions, this will certainly be significant... In real games, not so much.syzygy wrote:You claimed recently that having or not having KPK knowledge in whatever form really did not matter in terms of Elo.bob wrote:This makes no sense. Opposition is critical in KPK, for example. If you don't know about opposition, you have practically no chance of winning when you should win, or drawing when you should (from losing side)...cetormenter wrote:The Stockfish team tried experimenting with this. Perhaps not enough effort was put into the idea but in the end the tests failed. Surprisingly it seems that NOT having the opposition did better than having it. However this probably was just statistical noise and one of the tests got lucky/unlucky.
http://tests.stockfishchess.org/tests/v ... 344346beea
http://tests.stockfishchess.org/tests/v ... 344346beec
Anyway, Stockfish has a bitbase for KPK.
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BeyondCritics
- Posts: 415
- Joined: Sat May 05, 2012 2:48 pm
- Full name: Oliver Roese
Re: King opposition
Hi Lucas,
to introduce myself: i am a C++ programmer and a FM, but not a chess programmer.
Now to your question:
You messed it up somewhat. Cases 1/ and 3/ are direct and diagonal opposition, this is correct. But case 2/ is not opposition in any sense of it. Instead kings on d4 and d8 would be a correct example of distant opposition.
You can look it up all on wikipedia: http://en.wikipedia.org/wiki/Opposition_%28chess%29
So what is "opposition" in any case?
You can say that you "have the opposition" in a legal position if and only if:
a) Your opponent has the move.
b) The color of the fields of your king and the enemy king are identically.
c) One of the following three cases applies:
1/ The "manhatten" distance of your king and your enemy king is exactly 2, in this case you have the "direct opposition".
2/Case 1/ does not apply but the rook distance is exactly 1, in this case you have the distant opposition.
3/ The bishop distance is exactly 1, in this case you have the diagonal opposition.
Which "opposition" is "better"?
As a chess player: Somewhat scary question, since there is no intrinsic value in having opposition, except you need it badly. But to answer the question: Direct opposition is "stronger" than distant opposition, which in turn is "stronger" than diagonal opposition. Nevertheless you should consider for what it is used for, typically to combat for space advantage.
E.g: You do not value a collecting move, but you do appreciate the result.
Putting on the hat of a chess programmer:
A human chess player would apply heuristic concepts to carefully selected "prototypically" lines with taste and common sense. An engine on the other hand is a sort of a tough nut i believe, that would apply a programmed heuristic stubbornly to any random position.
Correct me if i am wrong, but i believe a chess programmer would watch out for something that converts precious cycles into something that is sufficently useful in any case. Something that helps to quickly identify the gross blunders of a random opponent and according to the Steinitz principle the mean to do this is to attack early.
Playing unbalanced positions is like riding a bycicle as GM Short put it recently: You are obliged to do something at any time, otherwise you will fall.
So what does that mean concrete? First things first: Try to run your passer or produce a passer if you don't have one or collect some pawns to produce a passer or drive your king into enemy territory to collect pawns that block your potential passers.
How many random positions are covered with this bold strategy?
I guess nearly all.
Best regards
Oliver
to introduce myself: i am a C++ programmer and a FM, but not a chess programmer.
Now to your question:
You messed it up somewhat. Cases 1/ and 3/ are direct and diagonal opposition, this is correct. But case 2/ is not opposition in any sense of it. Instead kings on d4 and d8 would be a correct example of distant opposition.
You can look it up all on wikipedia: http://en.wikipedia.org/wiki/Opposition_%28chess%29
So what is "opposition" in any case?
You can say that you "have the opposition" in a legal position if and only if:
a) Your opponent has the move.
b) The color of the fields of your king and the enemy king are identically.
c) One of the following three cases applies:
1/ The "manhatten" distance of your king and your enemy king is exactly 2, in this case you have the "direct opposition".
2/Case 1/ does not apply but the rook distance is exactly 1, in this case you have the distant opposition.
3/ The bishop distance is exactly 1, in this case you have the diagonal opposition.
Which "opposition" is "better"?
As a chess player: Somewhat scary question, since there is no intrinsic value in having opposition, except you need it badly. But to answer the question: Direct opposition is "stronger" than distant opposition, which in turn is "stronger" than diagonal opposition. Nevertheless you should consider for what it is used for, typically to combat for space advantage.
E.g: You do not value a collecting move, but you do appreciate the result.
Putting on the hat of a chess programmer:
A human chess player would apply heuristic concepts to carefully selected "prototypically" lines with taste and common sense. An engine on the other hand is a sort of a tough nut i believe, that would apply a programmed heuristic stubbornly to any random position.
Correct me if i am wrong, but i believe a chess programmer would watch out for something that converts precious cycles into something that is sufficently useful in any case. Something that helps to quickly identify the gross blunders of a random opponent and according to the Steinitz principle the mean to do this is to attack early.
Playing unbalanced positions is like riding a bycicle as GM Short put it recently: You are obliged to do something at any time, otherwise you will fall.
So what does that mean concrete? First things first: Try to run your passer or produce a passer if you don't have one or collect some pawns to produce a passer or drive your king into enemy territory to collect pawns that block your potential passers.
How many random positions are covered with this bold strategy?
I guess nearly all.
Best regards
Oliver