|Theme Bristol line-clearance : There is a parasitic white piece that moves towards a direction to open a line. A second white linear piece that gives or threats mate moves on the same line towards the same direction. The parasitic piece does not take part in the mating net.|
The theme took the name “Bristol”, because it first appeared in a problem tourney at the city Bristol in southwest England. Please notice that this chess problems composition contest took place in the year 1861 (!).
First Prize, "Bristol Problem Tourney", 1861
White plays and mates in 3 moves
The key move is impressive!
The rook moves in the first row to the right, to make space for the queen Qg6. The queen will move to square b1, and then it will move on the first row to the right, and it will give mate from the square g1.
Note that if the black knight Sb7 moves, there is an instant mate with Qd6.
2...Bb5 (to allow black king escape by taking Sb6)
In the final mate, Rh1 does not take part, and that is the reason we call it parasitic piece).
Clarifications about the presence of some pieces:
(1) The parasitic piece in the problem-17 (by Healy) is Rd1.
(2) The bishop Ba1 was put there to inhibit a second solution, having key [1.Ra1!]. The second solution would render the problem useless.
(3) If, instead of putting a rook on f3, the composer had put a white pawn on f3 to hold the black pawn f4, then other solutions would arise, (Key 1.Sc8 [2.Qb6+ Kxd5 3.Se7#]), and (Key 1.Sa8 [2.Qb6+ 3.Sc7#]).
|Theme black-Bristol : It is like theme Bristol, only with black pieces.|
|Theme bicoloured-Bristol : It is like theme Bristol, but the pieces have two colours.|
|Theme anti-Bristol : It is like theme Bristol, but the first piece prevents the second piece from reaching a critical square.|
In problem-17, we saw the clearance of a row. Let us see another problem with Bristol line-clearance, where the diagonal line a1-h8 is opened.
White plays and mates in 3 moves
There is only one variation, and that makes the problem rather easy to solve.
Key: 1.Ba1! Kxg2
In the mating picture the bishop is not taking any part, supporting or blocking, thus it is a parasitic piece.
You may read an essay by Milan R. Vukcevich below, where he presents, with many examples of problems of various types, the beauty of the Bristol theme.
Vuksevich mentions there that he was greatly influenced by his tutor Triantafyllos Siaperas.
(Update 26/02/2008) : We thank the International Master Harry Fougiaxis for his note that there was an inaccuracy on the definition of the anti-Bristol theme. He gave the following link for more details : page of Christian Poisson about themes.
THE BEAUTY OF BRISTOL
by Milan R. Vukcevich, USA
(From Mat Plus No.1, Spring 1994, p.2)
1. INTRODUCTIONThe Bristol theme obtained its name from a famous problem by Healey, which won first prize in the Bristol tourney of 1861. The problem caused a sensation, not unlike the one caused fifteen years earlier by the famous Indian Problem. This classic piece is shown in No.1.
2. THE BEAUTY AND THE CHALLENGEUnder the influence of Siaperas, line-clearances became my favorite themes. Bristols alone, account for ten percent of my published work! If you think this an exaggeration, in Chess by Milan, there are 216 problems, and 21 are Bristols. Since the book was published in 1981, the frequency of Bristols in my problems has been faithfully maintained.Why this fascination with something that is discarded by most composers as merely a visual effect? The answer is twofold: the beauty and the challenge. The beauty is the optical effect of a Bristol. The challenge is the fact that in a standard Bristol, the Q and another piece, usually a R or a B, are used in the main motif, and are difficult to be used for anything else. Also, the execution takes valuable space, reducing the number of squares available for other elements. Therefore, in a Bristol problem, the line clearence may be beautiful, but the rest of the thematic content may be very poor. An example is Healey's problem: there is nothing there but a beautiful Bristol. However, Siaperas' problem is clear proof that a true modern master can blend line clearances with other ideas.
As a matter of fact, I am convinced that in every era of the history of chess problems, only the best composers were able to produce great contemporary Bristols: Loyd, Kubell, Hanneman, Hartong, Loshinsky, Petrovic, Würzburg... If all of these greats found something worthwhile in the Bristol theme, one should search for its value. I challenge all who like to say how outdated the Bristol is, to try to create within the restrictions of this demanding motif.
Let me explain this last bit about the restrictions. Imagine that you are a writer. The clearest, the easiest and the most natural way to express yourself is by writing prose. It is much more difficult to express yourself writing poetry. Rhymes and cadences get in the way of accuracy. But if you have talent, and you work hard, the result will be a passionate and lyrical statement. In other words, the composers of Bristols are poets, and the rest write prose.
3. TWOMOVERSOver the years, the approach to the Bristol theme started to differentiate depending on the number of moves. Also, the black Bristol is now shown mostly in selfmates. These are essentially artistic choices which will change with time. Still, it makes sense to divide this presentation according the number of the moves and the type.
Abandoning the theme purity gave some of us great difficulty, and we concentrated on moremovers. Not until the problem by Kisis, No.7 did I realize how much of the Bristol beauty can be preserved even when purity is neglected.
Let me finish this section by summarizing my feelings on the artistic elements in these seven twomovers. Würzburg's problem is more beautiful than Nanning's, although the later has the same thematic content with a much better economy. The reason is that the impact of Würzburg's key is stronger than that of Nanning's because the clearence is longer, and the position naturally embodies more variations which conceal the key.
The purity of Bristols should be neglected in twomovers. Even with this modification of habits, a problem has to contain two or more Bristol phases. Since the Bristol setup is often obvious in a twomover (No.10 being an exception), there has to be some other element of beauty built in. For example, the two most obvious Bristols appear in No.8 by Kisis. The pathetically situated white queen is begging for a line clearence, but that obvious clue actually increases our appreciation of this proble m. There are two possible Bristols with a subtle difference, and that makes it a charming exercise for a solver.
As much as possible, the forward piece in a Bristol should not be laterally confined. For pure Bristols, Nos. 4 and 6 illustrate one technique, No.9 another. For impure Bristols, the confinement of the front piece is easier to achieve by exploiting the impure actions. Nos. 7 and 10 and tries in No.9 are good examples.
4. THREEMOVERSBristol problems are clear proof that it is much easier to let your imagination fly when you have more time: although it is a two-move maneuver, it was implemented most successfully in threemovers and longer problems.
The Bristols in the above problem are still the two-move maneuvers. In threemovers, the Bristol can be expanded, as shown by Petrovic in No.12.
5. MOREMOVERSThe longer Bristol problems are mostly fourmovers. This is due to neglect rather than to any thematic limitation. After all, did I not already prove that this theme is a timeless spark of beauty. Be it as it may, more moves offer more possibilities for thematic expansion.
6. SELFMATESBristols of many forms are popular in heterodox problems. The best known is the black-white form, where a black line piece clears the way for a white piece. There are hundreds of examples, many exceptionally good, and well known. However, I want to stay with the monochromatic themes, in particular the black Bristol in self-mates. This is an exciting area which is not completely explored.