Thursday, October 23, 2014


Regularly on this blog I disclose flaws of our best engines. Sometimes to compare engines. At other moments to proof that some ideas discovered by humans, can still not be coded in an algorithm. Despite the flaws few will doubt about the usefulness of the engines. Even my team-captain Robert surprised me a few days ago by including some engine-evaluations in his report which a few years earlier was simply unthinkable. We can't deny the fact that the engines have surpassed us largely in strength. Only some time ago Carlsen stated in an interview: "I can't beat the best computers".

Quality Chess recently published a nice example of how big the difference in strength is today between human and computer. The writer asked a + 2650 player how many big mistakes (direct wins or an important tactical sequence) he made in 24 games (some opponents had only 2200 elo). An engine could quickly find 10 mistakes despite the moderate opposition. As 2300 player I obviously make many more of those big mistakes. Some of those are surely avoidable but I believe there are also mistakes which can'be prevented via an optimal time-consumption or tactical trainings.

In round 6 of Open Gent I and my opponent missed a beautiful tactic. It was the only flaw in otherwise a pretty smooth victory. Just before going to bed after the play-day  I discovered it with an engine. I can't resist the temptation to check immediately just finished games with an engine despite the late hour, often after midnight. Some players surely won't agree with such attitude as they find it bad for the night's rest.

A fantastic move which initially the engines evaluate as equal for black but when giving more time they anyway find a big advantage for white in the complications. The piece-sacrifice creates an interference between queen and bishop. Such type of interferences are really rare in practice but it is well-known in the world of chess-compositions. There exists a bunch of themes on (Holzhausen) interferences. In the next paragraphs I will explain in a nutshell the different possibilities as this is an interesting and beautiful little niche of chess.

The Grimshaw was already covered in my article chess-compositions as it was multiple times used in my problem Loyds organ pipes. A Grimshaw is a mutual interference of 2 pieces. The simple example below demonstrates this theme.
Grimshaw-problem White mates in 2 moves
When the mutual interferences of the 2 pieces happen due to a piece-sacrifice then we call it a Novotny. In problem-chess this is rather ordinary so it is in most cases included in a bigger concept. I selected a rare example from board-practice which explains in its simplicity well the idea.

If the Novotny is created by pieces moving in the same direction (diagonal or vertical) then we call it a Plachutta. A simple but clear example from the American top-composer William Anthony Shinkman can be found below.
Plachutta-problem White mates in 3 moves
My game-fragment is not a Plachutta despite there was a piece-sacrifice and the queen + rook move rectilinear. There is only 1 interference instead of 2. The queen can't take the knight because the queen will be captured and not because the rook will be interfered. Finally when we have a Plachutta on one and the same line then we talk about an Anti-Bristol. This last one is the most complex theme and it is much harder to find a good self-explaining example.
Anti-Bristol White mates in 3 moves
The theme Anti-Bristol originates from the Bristol-clearance which I already covered in my article problem-moves. So many different types of interferences exist. You don't need to know this to play chess well but I do find it entertaining. Aren't we playing chess first and foremost to enjoy, right?


Grimshaw-problem: 1.Qb1 (menaces Qb7#)
1...., Bb2 2.Qh1# The bishop interferes the rook.
1...., Rb2 2.Qf5# The rook interferes the bishop.

Plachutta-problem: 1.d5 (menaces Ra8# en Rg8#)
1...., Bxd5 2.Rg8+ Bxg8 3.Ra8# The bishop interfered the queen.
1...., Qxd5 2.Ra8+ Qxa8 3.Rg8# The queen interfered the bishop.

Anti-Bristol: 1.c3 (tempo)
1...., Qc6 2.Pd6+ Qxd6 3.Ne3# The queen interfered the rook.
1...., Rf6 2.Be6+ Rxe6 3.Na3# The rook interfered the queen.

Tuesday, October 7, 2014


If there is today one player capable to win games with a minimalist approach then surely it is the reigning world-champion Carlsen. Time over time he proves that playing solid moves is often sufficient to let the opponent crack. Not everybody is enthusiast about such style of playing which e.g. can be read in the reaction of the German honorary-president Robert von Weizsacker. Soulless, boring, this has nothing to do about who is the better player but just who can sit the longest concentrated at the board (sitzfleisch) , are some of the harsh reproaches.

I don't want to discuss here if Carlsens games are attractive or not as there is no accounting of taste. However what I do want to extract is that most players even in equal positions aren't able to maintain the balance. On my level this is of course even more relevant. My article my most beautiful move discuss this aspect in detail. My opponents play much less stable than Carlsen opponents whereby it often is sufficient to avoid big errors to win a game. By applying such cautious approach my games often last longer than average. I must admit that the simul which recently I gave in Veurne due to this approach drifted into an exhausting marathon. My apologies for those being upset by this.

So I find Stevens reaction on my previous article a bit exaggerated. Games really don't end quickly in a draw because on 1 or 2 moments not the most critical move was played. Besides before complaining about the number of draws, we should first check if we apply sufficiently Sofia rules. It has little meaning to demand more aggression if too easily premature draws are made. On the other hand I do have to admit that the reaction also includes some truth. Sometimes the opponent neither makes clear mistakes and more than a draw can't be achieved without taking some risks. This also happened in my game against Andrew Stone.

That is also the reason why at move 42 I suddenly made the decision to sacrifice a piece for 2 connected white pawns. With less than 5 minutes remaining on the clock I must admit that it was mainly intuitively but soon it became clear that the sacrifice was fully sound. After the game I told Kara that I only found the idea very late in the game when I figured out that playing solid moves is not sufficient to win. Kara replied that the sacrifice is well known from the King's Indian. Nowadays I am reading Kasparov series of My Great Predecessors to improve my knowledge of chess-history. It is a must for me with my limited repertoire but I hadn't encountered before this sort of sacrifice in the few King's Indian games which I already replayed.

Following Kara's advice I replayed also all the won games in the King's Indian of former wc-finalist David Bronstein and the French grandmaster Igor Nataf both specialists in this opening but I could not find examples of sacrifices on g4. Besides g4 looks weird in the King's Indian so maybe there is a confusion with the standard sacrifices on h3. There are many types of sacrifices. I can distinguish 3 big categories of light piece sacrifices for 2 connected pawns.

A first category is the sacrifice in the endgame. A light piece is sacrificed to obtain 2 connected and far advanced pawns which overpower the opponents extra piece. I remember an anecdote of the reigning Belgian champion Geert Van der Sticht whom after a painful defeat against former world-class-player Michail Gurevich ventilated his emotions.

After the game Mikhail made a witty remark something like "Elementary, my dear Watson" which obviously wan't very pleasant for Geert. The piece-sacrifice was surely not winning but gives very dangerous practical chances. Now a player of the strength like Mikhail knows many more bricks than most players so he was right. A variation of this theme can be found in the famous game Capablanca - Lilienthal which is covered in My Great Predecessors part 1.

A second category is well known as it initiates a king's attack. The pawn-shield in front of the king is dismantled after which the king is under fire. As a special example I selected a King's Indian game with a piece sacrifice on g4 of which I earlier stated not have found any examples. Well the difference exists in the fact that white and not black sacrificed.

Finally we arrive at the most difficult category and those are the more positional piece-sacrifices. There is no direct king's attack and no immediate promotions are threatened but the opponent is mainly restricted in activity. A beautiful example is without doubt Bronstein - Botvinnik which we can find back in My Great Predecessors part 2.

I believe you can find the 3 different sort of bricks in my game with Stone. When I execute the piece-sacrifice, we already deal mainly with an endgame. However earlier in the game the piece-sacrifice was also possible and the conditions different. Below my analysis discuss the different possibilities in detail.

The analyses took a lot of time especially because today's engines are still pretty helpless in planning such piece-sacrifices. To learn chess consists of studying a large amount of such bricks and engines aren't the best teachers hereby. I realize more and more that it is vital for the own chess-development that we have to study the classical masterpieces from our rich chess-history.