Tag Archives: endgame

ICCF Rant 1: Rating snobbery

In what circumstances do you offer or accept a draw in online correspondence chess? I apply a number of tests.

First, I look at the position from the point of view of an experienced OTB player. Is the position simple or complicated? Is it likely to be drawn with correct play? What is my technical knowledge about this particular kind of ending?

Then I check the engine evaluation. If all the lines on all my engines point to 0.00 or close to that, I know the engines don’t think either side is winning. These engines outrate me by over 1000 points. I have to respect that.

Also I take into account my opponent’s play so far. Has he played sensible moves of the kind that a strong human or an engine would play? Does it look as though he is playing with engine support?

If all these boxes are ticked, then I will offer or accept a draw. Notice one test that’s missing – the difference between my rating and my opponent’s rating. I will gain a few points if my opponent is higher-rated and I will lose a few points if my opponent is lower-rated. That’s just how it goes. I am trying to be objective about the position.

In an ideal world, my opponents would take the same approach as me. Many of them do. Unfortunately some of them do not. Let me illustrate that with some examples.

This is from the game Rodney Barking – Player A.

Player A (not his real name) is from England. He has been playing correspondence chess for many years. He is a prominent figure in the world of English correspondence chess but as far as I can tell has never played rated OTB games. At the start of our game, he outrated me by about 150 points.

In this position, I have just played 31.Rbe1. It seemed to me that neither side could make progress. The engine evaluation was 0.00 or slightly better for me across all lines going nearly 50 moves deep. So I offered a draw… which he declined. In correspondence chess you are limited to one draw offer every 10 moves. So I had no choice but to play on.

This is the position after I played 41.Rf4. The position is even more drawish than before. The pawn structure is symmetrical. Neither side has any threats. The engine evaluation is even more firmly 0.00 at over 50 moves ahead. Again I offered a draw, and again my opponent declined.

A few moves later, queens came off leaving a rook and pawn ending that not even Magnus Carlsen could win:

At this point, after his move 49…Rd7, he offered a draw which I accepted.

I have been trying to understand why he turned down the first two draw offers. One possible explanation is that he does not understand the basic principles of chess endings and simply plays whatever move his computer recommends. Maybe he does not know that this type of position is drawn. I think this is unlikely given his high rating and his many years of experience.

A second possible explanation is that he is using a different chess engine that tells him, contrary to the range of engines that I use, that Black is winning these positions and therefore he should play on. Again I think this is unlikely. From what I know of chess engines and how they evaluate positions, none of them would regard this as a winning position. Unless maybe it had become corrupted and had accepted a bribe from Player A in the form of a promise of a processor upgrade.

The only other explanation is that Player A thought his rating advantage of 150 points was sufficient for him to outplay me from a drawn position or that I would make a mistake. In order to think this he would have to set aside the progress of the game so far, in which I (in fact both of us) have played error-free chess. He would also have had to close his mind to the possibility that I might have engine assistance, so that he is not playing a 2200-rated player but a 2200-rated player with the backup of a range of 3500-rated computers.

In short, I think he turned down the draw offers, not because an objective evaluation of the position led him to think he could win, but simply because his rating was higher than mine. That’s rating snobbery and it does him no credit.

Here’s a different example of the same thing.

This is from the game Rodney Barking – Player B (also not his real name). He is an American player who has been playing correspondence chess for less than five years. At the start of this game, he outrated me by over 350 points.

The position is quite different from the other game. It’s unbalanced and tactical in nature. Black has a dangerous advanced b-pawn. I was the exchange up, but have just offered it back by capturing his bishop on e6 (31.Rxe6). He has only one good move (recapturing the rook) – everything else loses – and then my queen and rook combine against his exposed king to force perpetual check resulting in a draw by repetition within a few moves. The engines see this instantly. The lines are forcing, and at all critical points Black’s only choice is between perpetual check or an immediate loss. So I offered a draw… which he declined.

The game continued 31…Rxe6 32.Rc8+ Kf7 (forced since 32…Kh7 33.Qd3+ wins for White) 33.Rc7+ Re7 34.Qd5+ Kg6 (the only other legal move, 34…Kf8, also results in a quick draw after 35.Qd8+ or 35.Rc8+) 35.Qd3+ Kf7 (all other moves allow a forced mate in at most 9 moves) 36.Qd5+ Kg6 and at this point he offered a draw which I accepted.

What made him refuse the initial draw offer? Any engine would have told him that the best he could hope for was a draw by repetition. Was he not using engines and relying on his own natural ability to outplay me in a tactical position?

Or was he simply making the point that chess etiquette requires the draw offer to come from the stronger player? I understand that point, but in online correspondence chess with computer backing, the concept of the “stronger player” no longer means anything. Nor does “higher-rated.” Come on guys, it’s time to join the 21st century.

Endgame tablebases

I’m going to start this post by quoting an extract from the Wikipedia entry, since it says what I want to say and I don’t see the point of paraphrasing it.

An endgame tablebase is a computerized database that contains precalculated exhaustive analysis of chess endgame positions. It is typically used by a computer chess engine during play, or by a human or computer that is retrospectively analysing a game that has already been played.

The tablebase contains the game-theoretical value (win, loss, or draw) in each possible position, and how many moves it would take to achieve that result with perfect play. Thus, the tablebase acts as an oracle, always providing the optimal moves. Typically the database records each possible position with certain pieces remaining on the board, and the best moves with White to move and with Black to move.

Tablebases are generated by retrograde analysis, working backward from a checkmated position. By 2005, all chess positions with up to six pieces, including the two kings, had been solved. By August 2012, tablebases had solved chess for almost every position with up to seven pieces, but the positions with a lone king versus a king and five pieces were omitted because they were considered to be “rather obvious.”[1][2] These positions were included by August 2018.[3] As of 2022, work is still underway to solve all eight-piece positions.

Tablebases sometimes come with a name as a prefix, e.g. Nalimov, Lomonosov, Syzygy. Eugene Nalimov is a computer programmer who generated the first tablebases in the 1990s. Lomonosov is the name of a Russian supercomputer. Syzygy is an astronomical term describing the occurrence of three celestial bodies in a straight line. No, I don’t know what that has to do with chess either. Syzygy 7-piece tablebases are the most recent. These are used by the International Correspondence Chess Federation.

What is the practical use of a tablebase in correspondence chess? In my experience the tablebase is a means of bringing a game to an end quickly and so achieving a draw or a win, when your opponent cannot or will not see this, and particularly when he or she has slowed the game down in order to delay the inevitable. The ICCF rules allow you to claim a win or draw by reference to a tablebase where there are no more than seven pieces on the board. Here’s an example from one of Barking’s games earlier this year.

White: Maurizio Mangiarotti (1958), Black: Rodney Barking (1915).
D45: QGD Semi-Slav.

Yes, I know there are more than seven pieces… This was the position after White’s 41st move. Earlier I had given up my queen for a rook and bishop. As all the pieces are on one side of the board, and there are no passed pawns, Black can hold the draw easily enough and in fact the evaluation of one of the chess engines I use is 0.00. However, White can continue the game for quite a long time just by probing with the queen.

As I’m not winning this position, there’s no advantage to me in prolonging it. What’s the quickest way out? Answer: sacrifice some material…
41…Bxh4! 42.gxh4 Rxg4+ 43.Kh3 h5

Despite the material difference, this position is actually drawn. Black has constructed a fortress. There is no way the white king can penetrate Black’s defences. I offered a draw, which my opponent accepted.

The point that’s relevant to this post, and obviously I checked this before going nuclear, is that the position is a tablebase draw as well. I would have claimed a draw by reference to the ICCF tablebase if my opponent had not co-operated. This is what the tablebase evaluation looks like:

Interestingly, the various engines I use all evaluate this position differently. The strongest of them has White at +0.81 (approaching a clear advantage, but not yet winning). The weakest has White at +4.21 (a trivial win). I guess none of the engines has the 7-piece tablebase programmed in. Maybe that should not be a surprise as the storage size you need for a tablebase is absolutely huge.

I was going to give a further example, another game against my Austrian opponent Herr Wiesinger. We have reached a rook and pawn ending where the Austrian is totally lost. He knows this and has slowed the game down to a funereal pace. Unfortunately there are still eight pieces on the board so we are just out of tablebase range. I expect one of his pawns to drop off very soon (when he finally gets round to moving) and then it will be Goodnight Vienna.

So much for correspondence chess. What about tablebases in OTB chess? Now here’s a thing. Chess leagues are increasingly using incremental time controls. These carry the risk that a game may still be going on at the end of the playing session. Back in the day, if the two players couldn’t agree on the outcome, these games were resolved either by adjournment to a later date or by adjudication. Neither of these is ideal. Adjournments simply add to fixture congestion. Adjudications take the result of the game out of the hands of the players and transfer it to a third party (in Barking’s eyes this is a detestable practice).

The London League used to rely solely on adjournments, following a playing session of 30 moves in 90 minutes. Those days have gone. At some point in the past decade, the League introduced an incremental time control of G75 + 15. So far, there have been no documented cases of games being unresolved at the end of the playing session. But adjudication is available as a backup if needed.

This season, and as far as I know this is the first time this has happened in English league chess, tablebase decision-making has been introduced. If a game is unfinished, and there are no more than seven pieces on the board, the outcome is determined by reference to a tablebase rather than adjudication. This has the advantage of determining the outcome by objective rather subjective means since you know with certainty what will happen with perfect play on both sides, rather than relying on the human (no doubt computer-assisted) determination of the adjudicator. The relevant London League rule is as follows:

C8. UNFINISHED GAMES
C8.1 If any game is unfinished at the end of the session, both players and both captains shall record the position on the board. If the two sides cannot agree a result, then –

(a)  if no more than 7 pieces remain on the board, the result shall be determined by reference to a tablebase such as the Syzygy endgame tablebase at
https://syzygy-tables.info/?fen=4k3/8/8/8/8/8/8/4K3_w_-_-_0_1;

(b)  In other cases, both sides shall submit an adjudication claim to the league secretary together with a fee of £10. If only one claim is made, it shall be upheld without adjudication. Either side may appeal against an adjudication decision, providing supporting evidence, and on payment of a further fee of £10. The fees shall be returned to the relevant side if no adjudication is needed or if an appeal succeeds.

Whoever thought of this deserves a medal. Who says space can’t be conquered?!