Speelman's Agony #52

Glasgow 1970. The Junior International Invitation Tournament was an innovation, held in conjunction with the Scottish Junior Chess Association. Participants included nine players who had represented their countries in the 1970 Glorney Cup, held just a few months earlier at Bearsden, near Glasgow: Bailey, Bellin and Saverymuttu (England); Findlay, Holt, Rosenberg and Sinclair (Scotland); D. James (Wales) and O'Hare (Ireland). Added to that list were John Nunn (England), and Rajinder (Raj) Bhopal and Allan Radlow (Scotland).

The above photo we see at the very back: Iain Sinclair (l) and Michael Rosenberg (r). In front of Michael are Raj Bhopal and Eric Holt. The next row, from left to right, has Stan Beaton of Cathcart Chess Club, who was assisting with the tournament, R. O'Hare, David Findlay and Allan Radlow (partly hidden). In the front row, from left to right, is David James, John Nunn (15 years old), Richard Bailey, Robert Bellin and Seth[na] Saverymuttu. Here the results:

Source: Chess Scotland

Richard played in the British Championship in 1969 and 1970 but says “I never progressed at senior level with a mediocre (dormant) Elo rating of 2340. I stopped playing chess competitively in 1982 and emigrated to the Netherlands in 1983. After a brief flirtation with Volmac Chess Club, I met and married a Dutch lady (prophylaxis worthy of Petrosian – preparing for a Brexit more than 30 years in the future!). I now have two children and four grandchildren. My current hobbies are playing Bridge and Go badly, and singing in a local choir.”

The game Richard sent me is against Vernon Dilworth (1916-2004), the inventor of the famous Dilworth Variation of the Open Ruy Lopez starting 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0–0 Nxe4 6.d4 b5 7.Bb3 d5 8.dxe5 Be6 9.c3 Bc5 10.Nbd2 0–0 11.Bc2 Nxf2!?

Richard writes:

“This is a game that has worried me for a number of years since the computer chess programs tell me that Black is winning until very late in the game. I recently loaded Stockfish 8 and given enough time it looks as if it might reach a different conclusion but, at least on my computer, maybe not within the tournament time limit! My opponent is V.J. Dilworth who was a good amateur, but I don't recall him having a rating above 3000. So what exactly is going on here?”

My pat answer after just a short glance was that the engines were hampered by the horizon effect (of not analysing far enough to reach a proper conclusion) and I think that that's certainly correct. But before we look at the game itself, it's worth considering in general just what chess engines are and how we can try to work with them.

Although chess engines are nowadays able to defeat even the world's best players in single combat, they are still really only glorified and extremely sophisticated bean counters. What an engine does is to “maxi-min” the results of a move: that is find the move that maximises the minimum evaluation gained against the opponent's best line of response.

The evaluation functions are extremely complex and there are mechanisms (“singular extensions”) to ensure that lines aren't all abandoned at the same search depth but that critical ones are continued until the position supposedly becomes dormant. But if the lines are too long for the engine/hardware combination then a horizon effect can occur where it's fairly obvious to a person that something “ought to be there” but the engine does the arithmetic and decides otherwise.

Working with engines, the most critical thing is to try to use them as a tool, even though they are much better at tactics than us. If, for example, you hate the look of an opening position then there's no point is playing for it, even if your favourite engine is besotted, since you will very likely not be able to play well in a real game. Any chess player above beginner level, where everything is fuzzy, will have a feeling about the positions they reach during a game. When checking with an engine later, watch the computer evaluation and respect it but your gut feeling is more important in practical play.

There are some specific things you can watch out for though. One is a sudden drastic change in the evaluation which can mean only one thing: a more or less hidden tactic. Take this example from a mini-match in Wijk aan Zee where Anatoly Karpov had a disaster in the first game but still fought back to beat Larry Christiansen eventually.

Say you were playing through this game and that Christiansen had also missed Qd1. If you had an engine on and half an eye on it, then you would notice the sudden spike after 11...Bd6, stop and pay more attention. The engine would go “Ping Bd6” and you'd know.

Another important phenomenon is flat lining. This occurs in the endgame where every line ends in exactly the same evaluation and doesn't shift. And what it means is that whatever the value given, the endgame is really drawn.

For the sake of argument, we'll say it's White to play. With the pawn on the seventh, Black can always check the white king away from b6 and with care – for example after g4-5 he mustn't allow the king to settle on e6 when 1.Rd8 Ra6+ 2.Rd6 Rxa7 3. Rd7+ wins – he can draw.

However, computers “think” otherwise. When I chose to have three lines Fritz15 was all 4.14, Komodo 10 all 2.99 and Houdini 5 all 2.46. In all cases, once the evaluations are established they don't shift even if you leave the engines running for much longer. If the position were winning then these would go up to stratospheric levels given time but they flat line. because there is no way for the “advantage” to grow. White has significantly more beans than Black but can't make coffee with them.

On now to Dilworth v Bailey. Richard provided notes which I've used and I've added my own thoughts as JS, Apart from the odd thought, these start at move 20.

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