The opening according to Vitruvius
In this first article I will show, in more detail than in the User’s Manual, the principle which inspired the Vitruvius’ team in the construction of the Opening Book. With the help of an example I will also show how well our Book integrates itself with the Chess Engine to produce a very original style of play.
Alexander Shashin is a former theoretical nuclear physicist and Russian chess master who currently has completely dedicated his time to chess playing and chess instruction. He is known for his work which models chess on a Physical System.
Very briefly Shashin holds that in assessing any position on the chessboard we need to consider the following factors:
- Material (m) – a very simple notion analogous to the mass of a system.
- Mobility (p) – analogous to the kinetic energy of a system.
- Packing density – analogous to the density of a system.
- Expansion factor – the expansion factor is analogous to the potential energy of a system.
Shashin claims that these four ‘concepts’ are enough to identify the correct path to follow in any chess position (actually he does away with the concept of ‘plan’).
Now let us concentrate our attention on factors 1 and 2, and consider the other 2 factors equal for both players. We define
are respectively the total number of legal moves at White’s disposal and Black’s total of legal moves. p is a measure of mobility and to its every value we link a specific move selection algorithm:
A) p> 1. 25 corresponds to the TAL
- Search for an attack against some piece in the following decreasing order of importance: King, Queen, Rook, Bishop, Knight and Pawn.
- Optimal piece positioning (development – see later)
- Material gain
B) p< 0. 8 corresponds to the PETROSIAN
algorithm (defensive anti-TAL
play, increase packing density)
- If pieces are not well placed retreat (remember the Russian strategy against Napolean’s advance)
- Try to achieve a p value which will take us to the CAPABLANCA algorithm (C).
C) 0. 8<p< 1. 25 CAPABLANCA
algorithm (strategic attack):
- Optimal piece distribution
- Pawn mobility and advance
- If the position is still capablancian go back to (i) – cyclic algorithm
D) p=1.25 o p=0. 8 (boundary limits, note that one value is the reciprocal of the other) give biforcation nodes or CHAOS
These are positions in which human intuition is the best recipe and consequently present the toughest challenge to computers.
Shashin has made it known that he has not incorporated his theory in a rigorous algorithm for chess engines and that he considers such an enterprise full of promise.
It is precisely for this reason that I endevoured to produce the VITRUVIUS OPENING BOOK
From our tests on various chess engines we were able to conclude that:
- Present day Chess Engines are highly specialised in dealing only with particular chess positions
- In particular all top engines have a style very close to the PETROSIAN style as described above: rather conservative, very solid but frequently not very brilliant
And therefore tha top Chess Engines:
- Know very well how to play in PETROSIAN type of positions
- Have difficulty in dealing with TAL type positions and are completely in the dark in positions of the CAPABLANCA type and most particularly in CHAOS zones.
Taking into account the above considerations, in compiling the Book we started with a large set of high quality games and kept only those positions with positional motifs and unbalanced situations normally not congenial to chess engines (or better said to their evaluation function); then we filtered ouyt those positions which by Shashin’s criteria do not belong to the CAPABLANCA
type of position or do not fall in the CHAOS
Let us take the following line from the Book:
1. d4 Cf6 2. c4 g6 3. Cc3 Ag7 4. e4 d6
The King’s Indian is an opening which is notoriously difficult for all Chess Engines.
5. Cf3 0–0 6. Ae2
The classical variation, one of the strongest weapons at White’s disposal against the King’s Indian.
6... e5 7. 0–0 Cc6
The Mar del Plata o Jugoslav variation.
8. d5 Ce7 9. b4
This particular continuation was elaborated by Taimanov in the fifties: Black attacks on the King’s side, Black on the opposite wing.
9... Ch5 10. c5
According to GM Jorge Luis Fernandez, this is the sharpest continuation; instead 10. Te1 was very popular in the eighties.
10... Cf4 11. Axf4 exf4 12. Tc1
Defending the c3-pawn and pressuring c7.
12... h6 13. Cd4 a6
Blocking the advance of the White b-pawn and hence slowing down White’s attack on the Queen’s side.
The position is getting more and more interesting. (GM Krasenkow)
Grischuk thinks that here the King is safer.
The normal plan for White: Rooks to the centre and presure against the weak black pawns.
Suggested by Krasenkow
16. Tfd1 h5
Working out the value for p here we get 1.27 and we conclude that the position is of the TAL type.
Following are some assessments by human players and a selection of top engines.
Played by Ivanchuk (2746) against Grischuk (2748) at Nalchik 2009.
Only Vitruvius Human and Zappa Mexico II with Dissident Aggressor configured suggest this exchange sacrifice which by the way is considered very promising by.
Clearly this is not White’s only option, but it is certainly the most brilliant.
Let’s take a look at the alternatives:
17. Cf3 was suggested by Houdini and Critter (World n. 1 and n. 2 engines) and Hiarcs. Krasenkow gives it an ‘!’;
17. Te1 was chosen by Vitruvius Conservative, Spark and Stockfish;
17. c6 by Deep Shredder;
17. cxd6 by Komodo.
- Zappa Dissident Aggressor and Vitruvius Human are the only engines that distinguish themselves in the treatment of TAL type positions.
- Houdini and Critter, even if their choice is altogether correct, have an opposite type of assessment.
- Zappa Dissident Aggressor is a specific configuration of Zappa Mexico II and, normally, is a much weaker engine than Vitruvius Human
- Vitruvius Conservative has a more prudent style than Vitruvius Human, but not at the Houdini and Critter level.
Already we can appreciate how important Vitruvius’ suggestions can be, but let’s move on to anather position in this line.
17... Ah6 18. Dg3 h4
Now g4 and the h4-pawn are weak.
19. Dd3 Axc1 20. Txc1
According to Krasenkow, the white central pawns more than compensate the loss of the exchange.
20. . . Dg5
(unclear according to Krasenkow)
p=1. 25: the position is of the CHAOS
Possible continuations are:
21. Te1 the move chosen by Ivanchuk and suggested by Vitruvius Human (+0.81) and Zappa Dissident Aggressor (+0.51)
21. Tf1 by Houdini (+0.18)
21. Td1 Vitruvius Conservative (+0.50)
21. Tc2 Shredder (0.00)
It is clear that in a given position different engines can and do suggest very different moves, even their assessment can vary a lot. Again both Vitruvius Human and Zappa Dissident Aggressor suggest Ivanchuk’s move, a player known for his brilliant original style.
The concluding moves of Ivanchuk-Grischuk were:
21. . . Ad7 22. c6 bxc6 23. dxc6 Ae6 24. Ag4 24. . . Axg4 25. hxg4 Ce7 26. Dd1 Tab8 27. a3 Rg7 28. Te3 Df6 29. Cf3 Cxc6?! 30. Cd5 De6 31. Cxc7? Dxg4? 32. Dxd6+- Tbd8 33. Dxc6 Td1+ 34. Ce1 h3 35. Dc3+ f6 36. Txh3 Tc8 37. e5(1-0)
The example shown illustrates:
- Shashin’s theory in a practical game;
- how the top commercial engines tend to opt for less spectacular moves, and in any case are very distant from the creative thinking of the top human players.
- that Vitruvius Human, although slightly less strong than Houdini, can assess TAL and CHAOS type positions in a very original way and suggests moves that are generally not inferior than those of Houdini.
The Opening Book has therefore been compiled precisely to underline these very special features of Vitruvius. It is no surprise that IM Robert Flesher has been very much impressed by Vitruvius, comparing its play to that of Ivanchuk!
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Last Modified: Tuesday 13 March, 2012