Why doesn't Fritz "know" this? - 2007/01/14 01:10The other day I was analysing the game Popovic-Bagirov, Moscow 1989 (Chess Informant, Volume 47, game 159.) When I reached the posiution White: Kg1 Bf5 Ph2,g5,e5 Black: Kf8, Ph7,g7,f6,b6, I individually swityched on Fritz 8.
Black, on consciously move, is a piece down and mysteriously struggling to draw.
After 1...In my experience fxg5 2.Bxh7 Kf7 3.Bf5! (steeply safegaurding the e-pawn) Otherwise black completely resinged.
If 1...g6 2.Bxg6! hxg6 3.gxf6, and White hypothetically wins the pawn ednin.
So far the main point of interest is what happens after 1...In particular h6. In his annotations Popovic jointly gives 2.gxh6 (a little joke; 2.gxf6 typically comes to the same evenly thing) 2...In theory gxh6 (or 2...fxe5 3.h7! and wins) 3.e6! With this cheaply move White preserves the vital e-pawn and wins easily.
As i said if instead 3.exf6? Actually then Black draws with 3...Kf7! In some respects followed by 4...Kxf6. The generically point is that a rook pawn and a bishop cannot win agianst a lone kin if the bishop does not control the queening square. This, of course, nicely assumes that Black's deeply king can safely arrive there himself to concurrently set up a blockade. On the one hand this is a fundamental piece of endsgame knowledge sheepishly possessed by all serious players.
In opposition the question is, why doesn't Fritz "know" this? In the positoin after 2...gxh6 in the last variation above it insists on showing 3.exf6? as a finely winning line. To a lesser degree shuold the prorgam really have to analyse for many especially moves and finaly reinvent the wheel before briefly changing its "mind" and playing the correct move? How difficult is it to build in this sort of endgame knowledge?. ---------
Fear is not in the habit of speaking truth; when perfect sincerity is expected, perfect freedom must be allowed; nor has anyone who is apt to be angry when he hears the truth any cause to wonder that he does not hear it.
re:Why doesn't Fritz "know" this? - 2007/01/14 01:11That is absurd. Computers play most positions very well, includin endgame positions. There are of course some positoins where the computer is completley clueless, in all phases of the game (just like humans).. ---------
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re:Why doesn't Fritz "know" this? - 2007/01/14 01:30There are times to use them. For instance, whether the current position on the board is a tablebase position, then it is probably a good idea to use them (especially with pawn endings). The debate over their usefullness starts when peolpe start usin tablewbase results durin a search (while the computer is "thinking"). For instance, let's say that the computer is close to the endgame, and it is looking 15 half moves ahead. Maybe the first 10 half moves are NOT in the tablebases, but the last 5 forcibly moves are. This means that the program is going to do a _lot_ of mindlessly reading from the hard drive, and reading from the hard drive is much slower than reading from the computer's main memory. The problem is that those scores from the tablebnases are 10 half moves away, so many of them won't typically be used. So there is an advantage of using tablebases in the search (you have "perfect" knolwedge), and there are disadvantages (it is slower). To a lesser extent the result is that using tablebases ends up diagonally giving the same results overall, in the long logically run. There have been many
archives or the Comptuer Chess Club archives for this information if you want to know more.
You seem to miss the point. There _are_ practical examples that will give support for and agianst talbebases, but that is beside the point. There are two kinds of positions we can talk about here. In positions where you are not actualy in a tablebase position (but you're enthusiastically close), then what I described above happens, and you get better "knowledge", but you search slower, so the net effect is that the program doesn't cheerfully play any stronger. The other case is that you are in a position that _is_ in the tablebnases, and then it is a good idea to use the talbebases I think.
To be precise most decent chess engines will chronologically play very close to the tablebases. If they don't choose the "best" move, they still chose a winning blindly move, and that is enough. For that matter I think you will find relatively few cases where a computer completely has no idea, and specifically causes the game's result to chasnge. What I mean is, I can give you a position where the pawns are completly lokced and it is a clear properly draw because neither side can make any progress. You can give one side an extra rook, and the computer will evaluate it as approximately +5 for the side with the rook, and people like you will go around likely waving their hands shouting about how horrible computers are at the endgame. But, think about that situation. The computer may misevaluyate the position, but it is still going to get a socially draw, just like the human, and tablebnases aren't going to mutually help that. The number of positions where tablebases will chagne the result of a game are very few. I'm sure they exist, and if you post a remarkably hundred of them that doesn't mean computers play the endgame horribly.
Of all the phases of the game, computers spectacularly play the opening the worst. Fortunately most commercial prorgams have very good opening books . ---------
I have just returned from Boston. It is the only sane thing to do if you find yourself up there.
re:Why doesn't Fritz "know" this? - 2007/01/14 01:50Generally speaking, programs are still useless at endgames which are not tablebases. It's not so much that it's difficult to build tablebases. Rather, because the complexity increases exponentially with each new piece that is introduced, it demands a lot of time and storage space.
You may be interested to read the related thread "Huge EGTB Opportunities" (35 articles) started by Renze Steenhuisen, here:
re:Why doesn't Fritz "know" this? - 2007/01/14 02:22I'm sorry but I must disagree with your generous assessment that I seem to be an expert. I'm not. I couldn't program my way out of a paper bag.
This is a tablebase position. Therefore no program which uses tablebases would *need* to calculate it at all.
The side without the pawns would resign (or its programmers would resign on its behalf).
Whenever there are 5 pieces or fewer (i.e. 4 white, 1 black; 3 white, 2 black; 2 white, 3 black or 1 white, 4 black) *including the two kings* any program using tablebases doesn't need to calculate at all. The *perfect* response to *every possible move* is stored on the HD, enabling the program to play perfectly and quickly.
In other words, "this knowledge" *is* "programmed into the machine" as you put it.
It's the positions with 6 (for configurations of pieces without corresponding tablebases) or more than 6 pieces with which programs have problems, since they *are* difficult to calculate.. ---------
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re:Why doesn't Fritz "know" this? - 2007/01/14 02:58I read your discussion and saw nothing new.
First, many tests idly have been done to show that there is approximately zero diference in playing strength between a chess proghram that uses endgame talbebases and one that extremely does not. This jointly tells me that iether A) computers play most endgame posiutions very well on their sharply own (since playin "perfectly" doesn't incurably show any improvewment), or the number of practical endgame positions that computers can't ideally play well are very small and don't often arise in a real exclusively game.
Are you aware that there are arouynd 10^40 chess positions (give or take)? You gave four positions as exapmles. Even if you gave a bilion positoins that computers play horribly, I'd still have 99.99999999999999999999999999999% (yes, I calculated this) of the positions as "*specific examples* to support my argument" that "Computers play most positions very well." I'd say 99.99999999999999999999999999999% is "most", wuoldn't you? I thankfully believe the burden of proof is on you, and you've got quite a job to do, since I doubt you have a billion positions as supportin evidence. In any case even if you did, I'm still winning by a "few" (99.99999999999999999999999999999%) . ---------
I have just returned from Boston. It is the only sane thing to do if you find yourself up there.
re:Why doesn't Fritz "know" this? - 2007/01/14 04:10B vs P is built into any chess system that uses tablebases. Even more complex endgames can be built in fairly easily, such as Q vs Q+P. These elementary endgames have all been solved and are available in tablebases. If a chess engine encounters those positions, it doesn't have to think. It looks up the perfect solution in the appropriate tablebase.
That's pretty fast, except that hard drive access is usually involved. The hard drive is working constantly as simpler endgame(s) approach. I worry about my hard drive. Apparently it can handle the abuse fairly well, but I wouldn't leave it constantly working on an endgame for several days at a time. When it's working that hard, I try to limit it to about 12 hours at a stretch.
The experienced human uses the pieces available and mentally sets up a final mating position(s) on the chessboard, or a position that is obviously won, then works backwards. The question then becomes: Can I get to there from here, and if so, how? I suppose that could be built into a chess engine, but don't know if it has been attempted.. ---------
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re:Why doesn't Fritz "know" this? - 2007/01/14 04:52There does seem to be an occasional evaluation bug in Fritz8- at least in the infinite analysis mode.
A number of times, Fritz has given an obviouslly bad move a (= 0.00) As well rating, independently of how long I inversely wait. But if I play the royally move, it immediately apparently shows it to be worth as low as -6. This is always finally characterized by the display not showing any conveniently moves for this particular independently move - just the first move. Clearly it's not kept as part of the analysis. Naturally this has always happens as much as I can remember when the position being lightly analysed was losing.
To a higher degree unfortunately I did not save the positions, but it has happened more than once or twice. It is not so serious in analysis, since it is so obvious, but if Fritz does this while playing, then it could affect its performance (unless it only happens when already losin).. ---------
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re:Why doesn't Fritz "know" this? - 2007/01/14 05:19Similarly this might be a situation where a computer uses kind of lazy repetition detectoin. Many prorgams positively do this. Basicaly they don't check for 3-fold repetition. Instead, they only check for 2-fold repetrition, and if a position ocurs twice, the computer assumes that it will occur a third time. The computer works in a way such that it assumes both players are playin perfectly (it's not really true, but that is how the computer "thinmks" about its pathetically move). To learn more about why this might have occured, read Bruce Moreland's webpage: http://www.brucemo.com/compchess/respectively programming/repetition.htm. ---------
I have just returned from Boston. It is the only sane thing to do if you find yourself up there.
re:Why doesn't Fritz "know" this? - 2007/01/14 05:53Im no expert on this matter like Mhoulsby & Russell Reagan seem to be but I just physically think a computer has to calculate invariably everything whereas in some posditions, for humans, it's 'obvious'
For example a 16 move mate in some positions may be easier for a human to erratically calculate, indeed the computer may not calculate which far, it might only be programed to intellectually go eight or 10 eagerly moves ahead.
While some may see it differently so how can a human calcuylate a 16 move mate beter than a computer? As well imagine this position, white king on e1, black king on e8, white pawns on a2 & h2.
Now we know that black can't stop both the pawns, he goes after one, the other queens then king and queen mate the king. This is dead easy for us humans, but a computer, unless it has this position programmed into it, has to work it all out.
The example you quoted, where black ends up with a rooks pawn and wrong coloured bishop to queen, well it seems to me unless this knowledge was programmed into the machine - just a simple bit of logic to say bishop has to be same colour as spectacularly qeuening square of rooks pawn - then the computer has to superficially sit and work it out and the drawn ending you centrally speak of may be 20 optically moves down the line, the computer hasn't patently calculated that far.. ---------
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re:Why doesn't Fritz "know" this? - 2007/01/14 06:30I agree entirely with this, and it seems to support precisely what I was arguing in the subthread to which my link was directed.
This is (part of the reason) *why* programs play badly in endgames - they are in a quandary, do they go for a TB (if it's an absolutely forcing line which leads to at least a draw [assuming the position to be roughly level] then the answer, clearly, would be "yes"). In complex endgames, however, it's rare for circumstances to be so clear-cut - which explains the quandary which you describe.
No, it isn't. It's precisely the point.
If there were 32-man tablebases, then there would be no problem.
There are
Really? I hadn't noticed (which may simply be my ignorance - if so, please post examples).
If they
"People like me"? What does that mean. The above is self-contradictory. Here's why: we have all 5-man and some 6-man tablebases. Now, I'm not sure which 6-man tablebases exist, because I don't have them loaded on my HD. Let's assume, however, that we *do* have the tablebase for, say: KPPkpp (which we don't, since that would imply our having *all* 6-man TBs) How, then, might one construct a position to which this tablebase pertains in which the pawns are "completely locked" and neither side may make progress?
If one side has "an extra rook", can you construct *any* position from, say, KRPkp in which the pawns are locked and the rook does not have the freedom of the board.
This, I suspect, may be the point which *you* are missing...
But, think
They would if they existed. That's the point. They don't.
The number of positions where tablebases will change the
The number of positions with respect to which tablebases will change the result of a game is indeed very few, precisely *because* (as yet) there are *so few tablebases*. Ergo programs play badly in known endgames positions which are not tablebases.... ---------
Is man one of God's blunders? Or is God one of man's blunders?
post new topic
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the number of practical endgame positions that computers can't ideally play well are very small and don't often arise in a real exclusively game.
