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Member since Dec-31-08 · Last seen Jan-29-15
About Me (in case you care):

Old timer from Fischer, Reshevky, Spassky, Petrosian, etc. era. Active while in high school and early college, but not much since. Never rated above low 1800s and highly erratic; I would occasionally beat much higher rated players and equally often lose to much lower rated players. Highly entertaining combinatorial style, everybody liked to play me since they were never sure what I was going to do (neither did I!). When facing a stronger player many try to even their chances by steering towards simple positions to be able to see what was going on. My philosophy in those situations was to try to even the chances by complicating the game to the extent that neither I nor the stronger player would be able to see what was going on! Alas, this approach no longer works in the computer age. And, needless to say, my favorite all-time player is Tal.

I also have a computer background and have been following with interest the development in computer chess since the days when computers couldn't always recognize illegal moves and a patzer like me could beat them with ease. Now it’s me that can’t always recognize illegal moves and any chess program can beat me with ease.

But after about 4 years (a lifetime in computer-related activities) of playing computer-assisted chess, I think I have learned a thing or two about the subject. I have conceitedly defined "AylerKupp's corollary to Murphy's Law" (AKC2ML) as follows:

"If you use your engine to analyze a position to a search depth=N, your opponent's killer move (the move that will refute your entire analysis) will be found at search depth=N+1, regardless of the value you choose for N."

I’m also a food and wine enthusiast. Some of my favorites are German wines (along with French, Italian, US, New Zealand, Australia, Argentina, Spain, ... well, you probably get the idea). One of my early favorites were wines from the Ayler Kupp vineyard in the Saar region, hence my user name. Here is a link to a picture of the village of Ayl with a portion of the Kupp vineyard on the left:

You can send me an e-mail whenever you'd like to aylerkupp(at)

And check out a picture of me with my "partner", Rybka (Aylerkupp / Rybka) from the Masters - Machines Invitational (2011). No, I won't tell you which one is me.


Analysis Tree Spreadsheet (ATSS).

The ATSS is a spreadsheet developed to track the analyses posted by team members in various on-line games (XXXX vs. The World, Team White vs. Team Black, etc.). It is a poor man's database which provides some tools to help organize and find analyses.

I'm in the process of developing a series of tutorials on how to use it and related information. The tutorials are spread all over this forum, so here's a list of the tutorials developed to date and links to them:

Overview: AylerKupp chessforum

Minimax algorithm: AylerKupp chessforum

Principal Variation: AylerKupp chessforum

Finding desired moves: AylerKupp chessforum

Average Move Evaluation Calculator (AMEC): AylerKupp chessforum


ATSS Analysis Viewer

I added a capability to the Analysis Tree Spreadsheet (ATSS) to display each analysis in PGN-viewer style. You can read a brief summary of its capabilities here AylerKupp chessforum and download a beta version for evaluation.


Chess Engine Evaluation Project

Some time ago I started but then dropped a project whose goal was to evaluate different engines' performance in solving the "insane" Sunday puzzles. I'm planning to restart the project with the following goals:

(1) Determine whether various engines were capable of solving the Sunday puzzles within a reasonable amount of time, how long it took them to do so, and what search depth they required.

(2) Classify the puzzles as Easy, Medium, or Hard from the perspective of how many engines successfully solved the puzzle, and to determine whether any one engine(s) excelled at the Hard problems.

(3) Classify the puzzle positions as Open, Semi-Open, or Closed and determine whether any engine excelled at one type of positions that other engines did not.

(4) Classify the puzzle position as characteristic of the opening, middle game, or end game and determine which engines excelled at one phase of the game vs. another.

(5) Compare the evals of the various engines to see whether one engine tends to generate higher or lower evals than other engines for the same position.

If anybody is interested in participating in the restarted project, either post a response in this forum or send me an email. Any comments, suggestions, etc. very welcome.


Ratings Inflation

I have recently become interested in the increase in top player ratings since the mid-1980s and whether this represents a true increase in player strength (and if so, why) or if it is simply a consequence of a larger chess population from which ratings are derived. So I've opened up my forum for discussions on this subject.

I have updated the list that I initially completed in Mar-2013 with the FIDE rating list through 2013, and you can download the complete data from It is quite large (101 MB) and to open it you will need Excel 2007 or later version or a compatible spreadsheet since several of the later tabs contain more than 65,536 rows.

The spreadsheet also contains several charts and summary information. If you are only interested in that and not the actual rating lists, you can download a much smaller (594 KB) spreadsheet containing the charts and summary information from here: You can open this file with a pre-Excel 2007 version or a compatible spreadsheet.

FWIW, after looking at the data I think that ratings inflation, which I define to be the unwarranted increase in ratings not necessarily accompanied by a corresponding increase in playing strength, is real, but it is a slow process. I refer to this as my "Bottom Feeder" hypothesis and it goes something like this:

1. Initially (late 1960s and 1970s) the ratings for the strongest players were fairly constant.

2. In the 1980s the number of rated players began to increase exponentially, and they entered the FIDE-rated chess playing population mostly at the lower rating levels. The ratings of the stronger of these players increased as a result of playing weaker players, but their ratings were not sufficiently high to play in tournaments, other than open tournaments, where they would meet middle and high rated players.

3. Eventually they did. The ratings of the middle rated players then increased as a result of beating the lower rated players, and the ratings of the lower rated players then leveled out and even started to decline. You can see this effect in the 'Inflation Charts' tab, "Rating Inflation: Nth Player" chart, for the 1500th to 5000th rated player.

4. Once the middle rated players increased their ratings sufficiently, they began to meet the strongest players. And the cycle repeated itself. The ratings of the middle players began to level out and might now be ready to start a decrease. You can see this effect in the same chart for the 100th to 1000th rated player.

5. The ratings of the strongest players, long stable, began to increase as a result of beating the middle rated players. And, because they are at the top of the food chain, their ratings, at least so far, continue to climb. I think that they will eventually level out but if this hypothesis is true there is no force to drive them down so they will stay relatively constant like the pre-1986 10th rated player and the pre-1981 50th rated player. When this leveling out will take place, if it does, and at what level, I have no idea. But a look at the 2013 ratings data indicates that, indeed, it may have already started.

You can see in the chart that the rating increase, leveling off, and decline first starts with the lowest ranking players, then through the middle ranking players, and finally affects the top ranked players. It's not precise, it's not 100% consistent, but it certainly seems evident. And the process takes decades so it's not easy to see unless you look at all the years and many ranked levels.

Of course, this is just a hypothesis and the chart may look very different 20 years from now. But, at least on the surface, it doesn't sound unreasonable to me.

Any comments, suggestions, criticisms, etc. are both welcomed and encouraged.

------------------- Full Member

   AylerKupp has kibitzed 7490 times to chessgames   [more...]
   Jan-29-15 Carlsen-Anand World Championship (2014) (replies)
AylerKupp: <<Everett> I think Fischer abdicated before the beginning of that '74 match. June 27th, 1974 he resigned by letter to FIDE.> He did, but the question as to whether he was still World Champion or not depends on the answer to the question "Who owns the World Chess ...
   Jan-27-15 Tata Steel (2015) (replies)
AylerKupp: <chancho> Ding missed out on a defining moment by playing timid.> Yes, but it's understandable to be a little timid when playing the World Champion who is rated 132 Elo points above you, particularly on your first meeting. Ding's rise has been steady and I suspect that he
   Jan-23-15 The World vs Naiditsch, 2014 (replies)
   Jan-21-15 Ding Liren vs W So, 2015 (replies)
AylerKupp: <Marmot PFL> Thanks for the link to Vaisser vs Geller, 1982 . I wasn't familiar with that game. It's amazing how much preparation a level player must do in order to be able to compete at the highest level. And while watching the game the thought of 22...Ne7 like Vaisser ...
   Jan-19-15 Ivanchuk vs W So, 2015 (replies)
AylerKupp: <tamar> I think that knowing how long to run an engine analysis is one of the, if not THE, critical questions in computer assisted chess. Run it longer than needed and you waste time. Not run it as long as needed and you will get a misevaluation of the position. In the ...
   Jan-19-15 World Chess Championship Candidates (2014) (replies)
AylerKupp: <<Mr 1100> How about “long armageddon chess” (i.e., with near-classical time controls)?> As good an idea as any and probably better than most. My one suggestion, to eliminate wear and tear on those 2600-rated players, is to determine the initial, hopefully somewhat ...
   Jan-19-15 Arno Nickel (replies)
AylerKupp: <<isemeria> For example, the K + P vs. K endgames would be 3/4 wins for the stronger side. And I guess many other traditionally drawn endgames too.> I am not so sure. According to this link, , (see the Frequency table near the ...
   Jan-18-15 G Mohr vs Anand, 1988 (replies)
AylerKupp: <morfishine> How far did you get? I got as far as the first sentence of the Wikipedia article, "Mohr's circle, named after Christian Otto Mohr, is a two-dimensional graphical representation of the transformation law for the Cauchy stress tensor." Huh? But at least it ...
   Jan-17-15 Robert James Fischer (replies)
AylerKupp: <The Rocket> If we are to believe <>'s Opening Explorer, the most successful opening move is 1.Na3, with a White winning % of 82.6%. White's winning % for 1.e4 and 1.c4 are "only" 54.0% and 56.4% respectively. Alas, Opening Explorer contains only 23 games
   Jan-14-15 The World
AylerKupp: <PinnedPiece>, <OhioChessFan> I think that it is reasonable to lump all the World Teams together. After all, even for the <>'s World Team, the membership in the team changes from game to game as do the players voting in each game, even though there ...
(replies) indicates a reply to the comment.

De Gustibus Non Disputandum Est

Kibitzer's Corner
< Earlier Kibitzing  · PAGE 47 OF 47 ·  Later Kibitzing>
Premium Chessgames Member
  AylerKupp: <AgentRgent> I don't know when Kasparov started looking at the World Team's analysis. The earliest mention of it in the book was in the discussion of 11.Nd5 where Kasparov casually mentions "After I played Nd5 and saw that all the analysts recommended 11...Qxe4, I was worried." And "I sat down in my hotel room to study the position on my own. I looked at the World's latest recommendations, and I read Irina Krush's commentary." followed by a discussion of her analysis.

Just prior to that in his discussion of 10.Nde2 he indicated that "So far, everything was going according to plan. The game was still following the path of past experience, so little thought had been required up to this moment." It was during this discussion that he mentions that "10.Nde2 was the last move I made from Moscow. I was sitting in m study having just sent it down the line when it suddenly struck me: ' What about Qe6?'" He says that he started going through variations in his head and concluded by saying "It was a moment not of fear, but of apprehension. Then I reasoned, 'Fine, if it happens, I will figure it out'."

So it's not unreasonable to suspect that he started looking at the World Team's analysis after 10.Nde2. He might have looked at it earlier but, if he did, he probably didn't pay much attention to it.

The following is an interesting commentary during his discussion of 11.Nd5 which may have applicability to this game if GMARK plays 23...Nxd5: "I considered the variation 11...Qxd4 12.Nc7= Kd7 13.Nxa8 Qxc4 14.Nc3 Rxa8 15.Re1 Kc7 16.h3 Rc8 17.Be3 Kb8 18.Rc1, and White is better because Black's king is still a bit exposed. The material balance of a knight and two pawns against a rook is potentially favorable for Black, but it is difficult to restore coordination, so White has the better position." Of course, that assessment refers to a middlegame position with many more pieces remaining on the board.

Later, during the discussion about 12...Kd7, Kasparov has this to say in response to a comment by Boris Alterman indicating that Khalifman was involved in the game: "I had not been looking at the website in great detail so I simply hadn't appreciated the number of people on the World Team working against me, and in the case of Khalifman and his friends in St. Petersburg, the quality and depth of the analysis. Anyway, although the game hadn't gone exactly as I had wanted it to, I didn't sense any real danger."

And this is an "interesting" perspective from the discussion of 15.Nc3: "Many people on the bulletin boards said <during the game> (emphasis mine) that I had an unfair advantage because I could see the World's analysis. That was absolutely correct. That gave me an advantage – I wouldn't describe it as unfair though; it balanced the struggle. There were three of us with three computers versus thousands of them with hundreds of computers, so just the amount of positions they could analyze was immense. There was a chance that I could suddenly find myself in dire difficulties and it would simply be too late. There would be no blunder, no favor returned. From this moment on I realized we would have to work day and night to avoid defeat."

So it seems that if Kasparov is correct, at least some members of the World Team were aware that he had access to their analysis. Kasparov's rationalization is also interesting for emphasizing that he had a team of 2 additional people working with him (night and day!) and so perhaps the proper title for his book should have been "Kasparov and a few friends against the World". But I don't think that would sell as well. :-)

In fairness the World Team had the assistance of several grandmasters like Speelman, Khalifman, and Bacrot. And Krush would eventually (recently) become a grandmaster. Kasparov had this to say about it: "My point was that this game had long ceased to be an event where ordinary players could have their say. Everyone was following the suggestions from Irina and her group. It had turned into a tough professional game, and I did not like the pretense that it was otherwise." Do you agree with that assessment?

At any rate the game was lost for Black after 55.Qxb4 per the 6-piece Nalimov tablebases which indicate that White mates in 82 moves, and the longest non-pawn-move sequence is 39 moves. And at the position prior to the final controversy resulting from Krush's late recommendation submittal after 58.g6 White has a mate in 79 moves with the longest non-pawn-move sequence also 39 moves.

Premium Chessgames Member
  AylerKupp: OK, here are the tablebase wins per for those 2 positions in Kasparov vs The World, 1999. For some reason it lists almost all the moves but not all of them.

After 55.Qxb4:

click for larger view

Mate in 82 moves:

1...Qf3+ 2.Kg7 d5 3.Qd4+ Kb1 4.g6 Qf5 5.Kh6 Qe6 6.Qg1+ Kc2 7.Qf2+ Kb1 8.Qd4 Ka2 9.Kg5 Qe7+ 10.Qf6 Qe3+ 11.Qf4 Qg1+ 12.Kf6 Qb6+ 13.Kf7 Qb7+ 14.Ke6 Qc8+ 15.Kf6 Qd8+ 16.Kf5 Qc8+ 17.Kg5 Qc3 18.Qh2+ Ka1 19.Qe2 Kb1 20.Qf2 Qc1+ 21.Kg4 Qc3 22.Qf1+ Kc2 23.Kf5 Qc7 24.Qe2+ Kb1 25.Qd3+ Ka2 26.Qa6+ Kb3 27.Qe6 Ka2 28.Qf7 Qc2+ 29.Ke6 Qe2+ 30.Kxd5 Ka3 31.Qa7+ Kb3 32.Qb6+ Ka3 33.Qd6+ Ka4 34.Qd7+ Ka3 35.g7 Qd1+ 36.Kc6 Qa4+ 37.Kc7 Qa7+ 38.Kd8 Qb8+ 39.Ke7 Qe5+ 40.Kf7 Qf4+ 41.Kg6 Qg3+ 42.Kf6 Qh4+ 43.Ke5 Qg5+ 44.Kd6 Qf4+ 45.Kd5 Qf3+ 46.Kc5 Qc3+ 47.Kb6 Qe3+ 48.Kb7 Qe4+ 49.Kb8 Qe5+ 50.Kc8 Qc5+ 51.Kd8 Qa5+ 52.Ke8 Qh5+ 53.Kf8 Qf3+ 54.Ke7 Qe4+ 55.Qe6 Qh4+ 56.Qf6 Qe4+ 57.Kf8 Qa8+ 58.Kf7 Qd5+ 59.Qe6 Qh5+ 60.Kf8 Qf3+ 61.Ke7 Qb7+ 62.Kf6 Qf3+ 63.Kg5 Qg2+ 64.Qg4 Qd5+ 65.Kh4 Qd8+ 66.Kg3 Qg8 67.Kh3 Qh7+ 68.Kg2 Qg8 69.Kg1 Ka2 70.Qg3 Kb1 71.Qg2 Kc1 72.Qf1+ Kd2 73.Qf8 Qe6 74.g8Q Qe1+ 75.Qf1 Qe3+ 76.Qf2+ Qxf2+

From 1...Qf3+ to 4.g6: 4 moves
From 4.g6 to 35.g7: 31 moves
From 35.g7 to 74.g8Q: 39 moves

After 58.g6:

click for larger view

Mate in 79 moves:

1...Qf5 2.Kh6 Qe6 3.Qg1+ Kc2 4.Qf2+ Kb1 5.Qd4 Ka2 6.Kg5 Qe7+ 7.Qf6 Qe3+ 8.Qf4 Qg1+ 9.Kf6 Qb6+ 10.Kf7 Qb7+ 11.Ke6 Qc8+ 12.Kf6 Qd8+ 13.Kf5 Qc8+ 14.Kg5 Qc3 15.Qh2+ Ka1 16.Qe2 Kb1 17.Qf2 Qc1+ 18.Kg4 Qc3 19.Qf1+ Kc2 20.Kf5 Qc7 21.Qe2+ Kb1 22.Qd3+ Ka2 23.Qa6+ Kb3 24.Qe6 Ka2 25.Qf7 Qc2+ 26.Ke6 Qe2+ 27.Kxd5 Ka3 28.Qa7+ Kb3 29.Qb6+ Ka3 30.Qd6+ Ka4 31.Qd7+ Ka3 32.g7 Qd1+ 33.Kc6 Qa4+ 34.Kc7 Qa7+ 35.Kd8 Qb8+ 36.Ke7 Qe5+ 37.Kf7 Qf4+ 38.Kg6 Qg3+ 39.Kf6 Qh4+ 40.Ke5 Qg5+ 41.Kd6 Qf4+ 42.Kd5 Qf3+ 43.Kc5 Qc3+ 44.Kb6 Qe3+ 45.Kb7 Qe4+ 46.Kb8 Qe5+ 47.Kc8 Qc5+ 48.Kd8 Qa5+ 49.Ke8 Qh5+ 50.Kf8 Qf3+ 51.Ke7 Qe4+ 52.Qe6 Qh4+ 53.Qf6 Qe4+ 54.Kf8 Qa8+ 55.Kf7 Qd5+ 56.Qe6 Qh5+ 57.Kf8 Qf3+ 58.Ke7 Qb7+ 59.Kf6 Qf3+ 60.Kg5 Qg2+ 61.Qg4 Qd5+ 62.Kh4 Qd8+ 63.Kg3 Qg8 64.Kh3 Qh7+ 65.Kg2 Qg8 66.Kg1 Ka2 67.Qg3 Kb1 68.Qg2 Kc1 69.Qf1+ Kd2 70.Qf8 Qe6 71.g8Q Qe1+ 72.Qf1 Qe3+ 73.Qf2+ Qxf2+

From 1...Qf5 to 32.g7: 31 moves
From 32.g7 to 71.g8Q: 39 moves

Oct-07-14  DPLeo: <AylerKupp>, this is an interesting read but has not changed my opinion that GK could not have achieved the tablebase win position without reading our analysis. I'm actually more convinced than before because now I know that he was reading, using, and benefiting from our analysis much earlier than I realized!

His excuse of justifying the cheating because it turned into a "tough professional" game borders on ridiculous. The game was never billed as "ordinary players" against Kasparov and seconds. It was supposed to be Kasparov against The World.

Whatever it takes to help him sleep at night I guess. I know I'll sleep much better knowing it took him nearly 40 moves of reading our analysis along with the help of seconds to compete with us.


Premium Chessgames Member
  AgentRgent: <"I was sitting in my study having just sent it down the line when it suddenly struck me: ' What about Qe6?'"> Revisionist aggrandizement! And almost certainly absolute bollocks based upon other comments he made at the time. His choice of words at the time (as I recall) "I congratulate The World on playing such a bold <and surprising> move."

<"I wouldn't describe it as unfair though; it balanced the struggle."> Justification for what he must have known was unseemly behavior.

<"Everyone was following the suggestions from Irina and her group."> The point he absurdly fails to comprehend is that "her group" consisted of "his opponents". Irina and the vast numbers of contributors WERE the World, whom else should "we" have listened to? Space Aliens?

<"At any rate the game was lost for Black after 55.Qxb4 per the 6-piece Nalimov tablebases"> 51...Ka1 was our draw. After the voting fraud, any opportunity to find further moves that might have drawn was lost as the vast majority of the analysts had quit the game in protest. Had we known at the time that Kasparov had been reading our analysis, we almost certainly would have done so much earlier!

My opinion of Garry is that he is a spineless and dishonorable man who is deserving of nothing but scorn for his behavior. Despite my distaste for the current Russian political situation, I cannot find it in myself to wish Kasparov well in his political endeavors, the failure of which I fully attribute to Karma being a female hound!

FWIW I spoke with Irina about the event just last year. While she was extremely gracious, my impression was that she was disappointed (to say the least) with the way it all turned out.

Oct-07-14  iatelier: <AylerKupp> Kasparov seems to be known as defending his acts, and turning everything upside down. Irespectively of 3 against 3000 that was the point: Kasparov vs. World (which includes other profis) - it wasn't Kasparov vs. Amateurs of the World. And he was wrong to peek into analyses - as imagine Morphy vs. Partners listening their consultations. Morphy would never do that out of his pride.

Thank you so much for the such elaborated reply about the Tablebases. Would it be correct to say that for certain small % of positions they would "disagree", as in the first place all those 'stored' endgame lines were computed at some initial stage, and we see very often that in the World games engines disagree?

Premium Chessgames Member
  AgentRgent: But I'm not bitter... ;)
Oct-08-14  DPLeo: < AgentRgent: But I'm not bitter... ;) >

Me either.     :-)

FWIW your comments seem more accurate than bitter to me. Besides, what's there to be bitter about now that we know he couldn't beat us without cheating. I don't even consider it a loss anymore!

Premium Chessgames Member
  AgentRgent: <DPLeo: I don't even consider it a loss anymore!> Indeed.. I consider the game Drawn as well.
Premium Chessgames Member
  AylerKupp: <<AgentRgent: But I'm not bitter ... ;)>

Of course not. Besides, look at all the fun you had and the opportunity to make history. But I hope that I never hear from you when you <are> bitter! :-)

Premium Chessgames Member
  AylerKupp: <iatelier> I did give you some bad information about what the Syzygy tablebases contain, see <tbentley>'s comment at AylerKupp chessforum. Sorry about that. From reading the available on-line information It's not always clear to me what data the different tablebases contain.

With respect to tablebases disagreeing, tablebase generation works the opposite of engine analysis. Engines start from the position you give them and search <forward>. Along the way they evaluate all the candidate positions according to their evaluation function which differs from engine to engine. They each also prune their search tree differently, Stockfish probably being the most aggressive, so they don't necessarily evaluate the same positions. Finally, search engines, particularly multi-core search engines, are non-deterministic. If you were to run an analysis with the same engine starting from the same position at different times you will get different results. This is apparently because of the interference of higher-priority operating system processes which, by interrupting executing processes or threads, affect the order in which the nodes are evaluated. And the search functions are very sensitive to move ordering, so if the move ordering is different then different branches of the search tree will be pruned according to each engine's search tree pruning algorithms.

Tablebase generators, in contrast, work <backwards> in what is called retrograde analysis (see, for example, They start with K vs. K positions and (presumably!) indicate that all these are drawn. :-) Then they add a pawn in each possible location for each possible K vs. K position and record the result (any promotion results in a win with the side with the pawn); these become the KPvK tablebases. Then they add a pawn to the other side and repeat the process; these become the KPvKP tablebases, etc. until all the possible variations have been considered up to the number of pieces for which the tablebases are generated.

So all the different tablebases for a given number of pieces consider all the positions reachable for those number of pieces. There is no search tree pruning, move ordering considerations, or evaluation function differences. So, subject to the absence of programming errors, they are all correct subject to the different information they contain (DTM, DTZ, etc.) and their compression individual scheme.

Premium Chessgames Member
  AylerKupp: <Interpretation of Stockfish 5 reported evaluations>

Stockfish 5, like all other engines, reports its evaluation of the last node for each line it displays, according to the value specified in the MPV UCI parameter. This evaluation is one of the following:

a. The value reported by its evaluation function in the range [-99.99] to [+99.99] depending (if the proper specification has been made to the chess GUI) whether Black has the advantage (negative numbers) or White has the advantage (positive numbers).

b. The number of moves to mate preceded either by "M" or "#" according to the GUI and "+" or "-" depending on whether White or Black is delivering mate. This mate condition is detected by the normal search plus evaluation process and is not derived from tablebase information.

c. A "special number" in the range < [-100.00] or > [+100.00].

Stockfish 5 uses a value of 10000 internally to represent known win positions and refers to this value as VALUE_KNOWN_WIN. These known win conditions are:

a. KX vs. K where X = "plenty of material"; i.e. KQ vs. K, KR vs. K, and KBN vs. K, provided that it isn't a stalemate position. Once it finds such a position it will return an evaluation of [100.00].

b. KBN vs. K. This is similar to KX vs. K except that the 2 kings must be in close proximity to each other and the defending king must be driven to a corner in order for the attacking side to win. Stockfish calculates evaluation bonuses for both of these conditions and the bonuses get larger the better these conditions are satisfied. The value of these bonuses get added to VALUE_KNOWN_WIN so the evaluation reported by Stockfish will increase for each search ply until the mating condition is achieved.

c. KP vs. K. These endgames are evaluated with the help of an internal bitbase to determine whether the positions are a win for the stronger side or a draw. Like KBN vs. K, bonuses are added to VALUE_KNOWN_WIN,; a material bonus for having an extra pawn (PawnValueEg = 258 for Stockfish 5) and a positional bonus which increases the further the pawn(s) are advanced.

Stockfish 5 uses a value of 32000 internally and refers to this as VALUE_MATE. As far as I can tell Stockfish uses does not adjust VALUE_MATE in any way. But it does scale the evaluation of mate conditions reported to the GUI to conform to both the UCI parameter reporting specification (evaluation reported in equivalent pawns) and formats it for "human readability" (number of moves to mate preceded by "#")

Nov-17-14  ketchuplover: Go Anand!!!!!!!!!!!
Nov-22-14  eddazeitz: Since I never checked my user profile I was quite surprised by your post Nov-19-14 in "The World vs Naiditsch". But you probably have a point with mentioning the change of my user name from edda zeitz to eddazeitz. Searching my memory I remember that sometime (after buying a new PC) I couldn't enter the kibitzing area and was requested to register anew. There I probably changed the spelling.

(By the way registration seems to be connected to the explorer you use. Out of curiosity I opened Opera (I am using Firefox) and was not allowed to enter the game without new registration.)

Premium Chessgames Member
  AylerKupp: <eddazeitz> (or <edda zeitz>, which one do you prefer?) I had a similar problem when I switched from Internet Explorer to Chrome. I suspect the reason is that our settings (user name, password, preferences, etc.) are kept on our computers as cookies, and that each web browser maintains its own set of cookies. I imported my IE links and cookies into Chrome when I started using the latter but this is a manual operation and they are not sync'd. And, since I still prefer IE over Chrome, I use the former more often and so they quickly get out of sync.

An even more puzzling situation happens when I'm running a chess engines that uses all the cores in my computer. I have it set up so that my chess engines run at low priority, so I can run any other programs without the chess engine interfering. At least most of the time. But sometimes when I try to access <> IE apparently can't find my user name and password and requires me to explicitly log in even though this doesn't happen if the engines are not running.

Computers; you can't live with them and you can't live without them.

And, BTW, I apologize again for thinking that you had not participated in earlier games.

Premium Chessgames Member
  truefriends: Dutch Top OTB players VS Dutch Top CC players:

Already finished:

Still ongoing:

Dec-20-14  isemeria: Hi <AK>,

Few day ago you wrote about <relative> and <absolute> evaluations in the Naiditch game page. It lead me to think about it a little.

I understand that calibrated absolute evaluations help when we compare the results from different engines. But here's the catch: isn't the evaluation function the essential thing that makes the difference in engines playing strenght? Compare to humans of different skill level: I look at a position and think white's slightly better, but Carlsen thinks white is winning.

For example, two engines evaluate some position:
- engine A: +0.75
- engine B: +1.07
The way we use to think is that it's a scaling problem, but perhaps it is a real strenght difference. One of the evaluations is more correct than the other.

But then neither is actually correct, because in addition to the mentioned evaluations, there's one even more absolute evaluation, let's call it <real> evaluation. It has only 3 different values: win, draw, loss. (I know you know this, and this one has more philosophical merit than practical for playing strenght.)

For example, in position where white can capture a knight or a queen, the <real> evalution for both is the same, other things being equal. But of course it's better to take the queen, because it makes the win easier. Nevertheless, after either capture white would be winning just as much.

Because of the existence of <real> evaluation, I don't know if it is possible to somehow define correctness of <absolute> evaluation. It's just an approximation for ordering the positions which are not solvable. You mentioned the relation between evaluation and winning probability. This would be useful of course.

Dec-20-14  isemeria: I'm not familiar with the evaluation functions. But let's assume there are two engines, which have the following evaluation functions.

Engine 1: E = a + b + c + d
where a king safety, b is material, c is central control, and d is space.

Engine 2: E = a + b + c + e
where a, b, c are the same as in Engine 1, but e is backward pawn on open file.

Is it possible to calibrate the numeric evaluation between engines, when the the functions have different terms in them?

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  AylerKupp: <isemeria> Thanks for taking the time to think about and comment on some of my thoughts. I have some thoughts in return.

I will first say that the evaluation function is not necessarily the essential thing that makes the difference in engines' playing strength. Sure, it's an important factor but other things like search depth are also important. For example, if engine A has a very accurate and detailed evaluation function it will likely be time consuming to calculate, and engine A could only reach a certain search depth in a given amount of time. Engine B might have a simpler and less accurate evaluation function, just an approximation to the <real evaluation>, but reasonably close. As a result, engine B's evaluations take less time to calculate, so engine B can reach deeper search depths in the same amount of time as engine A. Will engine B's deeper search compensate for engine A's more accurate evaluations? Hard to tell without the details, but this has apparently been Stockfish's approach for quite a while, so it seems like a reasonable strategy.

And there are other factors as well. The quality of an engine's search heuristics is (IMO), the most important component of an engine's playing strength. If engine A with its superior evaluation function were combined with the best search heuristics then it would do the best job in eliminating non-productive lines and many unnecessary node evaluations, thus compensating for the additional time required by its more complex (but more accurate) evaluation function. So the engine with the best heuristics would be able to reach the deepest search depths in the same amount of time, even with an evaluation function that is time-consuming to calculate. After all, the fastest evaluation function is the one that does not need to be invoked!

I would then say I think that your concept of <real evaluation> is too restrictive. I think that there is a <real evaluation> while a game is in progress or an analysis is being done (e.g. "White stands better"), we just don't know what it is and how to quantitatively express it. So I view the evaluations by engines, whether <relative> or <absolute>, but particularly the <absolute> evaluations to be approximations of the <real> evaluation. So, you're right, neither <relative> nor <absolute> evaluations are correct, they both have errors in them, namely the difference between their values and the <real> evaluation. The problem, of course, is that the value of the <real> evaluation is unknown.

This led me to a comparison of the difference between the actual value of a physical quantity and measured values of that quantity. All measurement equipment has errors, and measurement noise also needs to be taken into account. There are techniques (e.g. Kalman filters) for combining the results of various measurements to get a better approximation to the actual value of that physical quantity (e.g. a missile's position in space), but these require certain characteristics of the measured quantities like Gaussian-distributed noise that I don't think are applicable in chess position evaluations. And a sequence of chess moves is certainly not stochastic (random) or combinatorial but sequential. I have been doing research in more general filters and estimators to see if I can fit the problem of chess position evaluation into them (or vice versa) but so far without success.

As far as your last question, <Is it possible to calibrate the numeric evaluation between engines, when the functions have different terms in them?> my opinion at the moment is that I don't think so, particularly since we don't know what the terms are in commercial engines! I would mention that not only are the terms themselves unknown but also their relative importance (weights). Two evaluation functions could have the exact terms but different weights associated with them, giving different results. And it's a dynamic problem; I would think that, in general, the accuracy of the evaluation (or at least our <confidence> in the accuracy of the evaluation) increases with the search depth. So that's yet another factor to consider.

Dec-21-14  isemeria: Thanks for your reply <AK>. Helpful as usual.
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  Golden Executive: Merry Christmas and a Happy New Year <AylerKupp> to you and yours!
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  WinKing: Merry Christmas & Happy Holidays to you & yours <AK>! :)
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  wordfunph: <AylerKupp> Merry Christmas!
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  morfishine: <AylerKupp> I hope you have a very enjoyable Christmas and a Happy New Year!
Dec-26-14  cormier: Joyeux Noël ...
Premium Chessgames Member
  AylerKupp: Thank you all. And the same to all of you.
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