Tuesday, April 01, 2008

Line Openings (1)

We open a line to allow a piece pass through it, a piece from those we call linear, that is those moving on a straight line (rook, bishop, queen, even the pawn when it makes its first move with double step). There are various ways for the opening of a line (or line-clearance).

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 (!).

(Problem 17)
Frank Healey,
First Prize, "Bristol Problem Tourney", 1861
White plays and mates in 3 moves
#3 (12+7)

The key move is impressive!
Key: 1.Rh1!
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.Qb1 [3.Qb4#]
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.

(Problem 18)
Murray Marble,
White plays and mates in 3 moves
#3 (5+2)

There is only one variation, and that makes the problem rather easy to solve.
Key: 1.Ba1! Kxg2
2.h8=Q Kf2
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.


by Milan R. Vukcevich, USA

(From Mat Plus No.1, Spring 1994, p.2) 


The 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.
1. F. Healey
1.Pr. Bristol Tournament 1861
The solution is the surprising 1.Rh1!!. The reason for this becomes obvious on the third move of the only variation: 1... Be8 2.Qb1 Bb5 3.Qg1!#. The sole reason for the key is to open the first rank for the white Q. The details of the construction, in particular the useless Rf3 and the plug on a1, were chosen by the author to make the solvers suffer and to heighten the shock value of the solution.
2. J. Kohtz and
C. Kockelkorn

Neue Berliner Schachzeitung 1865
The Bristol theme can also be shown as a defense with black pieces. One of the best early examples is shown in No.2. After 1.d3. white threatens 2.Be4, followed by S mates at c4 and g4. Black defends with 1... Rh8! 2.Be4 Qg8!. However, now white plays 3.Bb2 and black is in Zugzwang because the Q trapped the R at h8, and black has no waiting moves. This element is called the anti-Bristol.
The appearance of the famous Healey problem prompted composer to discover other line-clearance strategies, the best known being Loyd theme. Both themes are beautifully shown by my teacher Siaperas in No.3.
3. T. Siaperas
1.Pr. Sah, 1948
The solution is 1.Re1! threatening 2.Q:d5+. After the two flight-blocks, 1... Qa4 2.Qe8+ Bc6 3.Qe2#, we finally see a beautiful Bristol. After 1... Q:a6 2.Qe2+ Bc4 3.Qe8#, a beautiful Loyd with two different flight Blocks.
Notice that in the Bristol clearence both thematic pieces move on the same line and in the same direction, while in the Loyd theme they move on the same line, but in opposite directions.To limit this paper to a reasonable size, I will concentrate on the Bristol theme. Also, I will favor the art at the expense of the theory. In other words, this is not a comprehensive article on all possible Bristols. This is a personal statement, which includes only those experiences which help formulate my own artistic criteria and composing techniques.


Under 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.


Over 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.
4. O. Wurzburg
Atlanta Journal 1939
Although the Bristol theme is a two-move combination, it was always extremely difficult to compose an acceptable contemporary twomover. The best example from the olden days is Würzburg's No.4. In the initial position, mates exist for all black moves, but white does not have a waiting key. In desperation, he plays the surprising 1.Ra8!, a Bristol which changes the mate after 1... f3 2.Qb8#.
5. W. Nanning
Handelsblad 1917
Nanning's No.5 has the same content, a complete block, and the Bristol key which change one of the mates: 1.Ba6! d4 2.Qb5#.

These two problems are theoretically equivalent, but Würzburg's piece is definitely a superior beauty: the line clearence is longer, and it has more variations and possibilities, which all serve to make the solution more surprising.
6. G.Guidelli
1.Pr. Good Companions 1919
These two problems were good in their time. Today, they would not qualify for any respectable journal. Modern twomovers are too complex and a problem with a single thematic variation would not excite anybody but a novice solver. Even the best composers could not save the classical two-move Bristol. The last example of any complexity was Guidelli's No.6.

Here, 1.Bh8! threatens 2.Rg5#. After 1... c5, follows the Bristol mate by the unpinned Q, 2.Qg7#. The non-thematic unpin, 1... Rc5 2.Qd1, completes this nice Meredith blend.
The revival of the twomover Bristols happened when the purity of purpose was abandoned. Let me explain this term, or "affliction". The thematic purity of purpose in a Bristol means that the only purpose of the move by the forward piece is to clear the line for the piece that follows it. The forward piece is not supposed to guard squares around the black king, and its opening move is not intended to change anything else in the position but the freedom of the other Bristol piece. In olden days, under the influence of the Old German school, composers were adhering to the purity of purpose in all themes, including Bristols. This is obvious from the problems discussed until now. Even later, when the New German school came around, many, including Siaperas, Petrovic, and myself, adhered stubbornly and publicly to the concept of pure-purpose Bristols. This is correct when the richness of the problem is not affected. A pure Bristol is artistically more striking than an impure one. However, in every great creation, content and art have to be balanced.In moremovers and often in threemovers, a pure Bristol can be shown without ill effects on the rest of the content. In twomovers, however, the purity has to be sacrificed to compose a problem which satisfies the modern taste for thematic complexity.
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.
7. I. Kisis
1.Pr. Problem 1962
#2 v8+7
Here, the try is 1.Ra1?, with a completely unthematic threat 2.Ra4#. The Bristol happens after 1... Se2 2.Qb1#. Other variations in this complex are 1... B:g4 2.Bd3#, and 1... S:g4!, which is the refutation. In the solution, 1.Rh8!, the threat is again unthematic: 2.Re8#. This time the Bristol happens after 1... Sg4 2.Qh7#, and the response to 1... B:g4 is changed to 2.R:f4#. Alone, neither these Bristols, nor the changed mate make a good problem. Together, they are an unforgettable combination.
8. F. V. Shultz
2.Pr. Mainpost 1956
#2 vv8+9
With the purity abandoned, Bristols started again appearing in twomovers. Some of these problems were even successful in strong tournaments, but the line clearances often looked anemic. For example, in Shultz's No.8, the thematic tries 1.Qa2? and 1.Qd2? are refuted by the Grimshaw moves 1... Be4! and 1... Re4! respectively. The Bristol key 1.Bc6! is an impure line clearance, which also protects the thematic square d5 after the Grimshaw moves. The impure purpose does not matter, but the clearan ce is short and lacks the impact of a true Bristol.
9. M. R. Vukcevich
3.H.M. Problem 1971
#2 vvv14+8
Years later, I composed No.9. Any random Bristol clearance of the Q, such as 1.Rc6?, threatens 2.Qc3#. However, black easily defends with either 1... R:f6! or 1... S:f6!. Two Bristol corrections are refuted by one or the other of these defenses: 1.Rc4!? S:f6 2.Sg6#, but 1... R:f6!, and 1.Rc5!? R:f6 2.d6#, but 1... S:f6!. The solution is the prolonged Bristol: 1.Rc8! R:f6, S:f6 2.Qc7#. An interesting technical point is how the lateral moves of the key piece are prevented, because they obstruct lateral movements of the Q: 1.Rb2? Bc2!, and 1.Rd2? R:e6+!. Note that the two Bristol corrections, 1.Rc4!? and 1.Rc5!? are impure clearances, but the solution is a completely pure double Bristol. Sadly, in the early 70's, I was still obsessed with the purity of purpose!.
10. M. Stosic
4.Pr. Shakhmaty v SSSR 1973
#2 v10+6
The most original Bristol combination was invented by Stosic, No.10.

In the try, 1.Qh1? gf4 2.Rg1#, the Q clears the line for the R. The refutation is 1... g4!. In the solution, 1.Ra1! Kf5 2.Qb1#, the R reciprocates and clears the line for the Q. There are three changed mates between these two phases. Note that neither Bristol is pure. In both phases the forward piece also makes lateral mates: the Q on e4, and the R on a6.
The last three problems dispel two notions: first that the Bristol is not for twomovers, and second that nobody appreciates it. A good judge understands the true achievement in line clearances. These three tournaments were very strong, and I remember being quite happy with the success in a competition which included Mansfield, Petrovic, Kisis, Tominic, Rice, Amirov and Valuska. Actually, I was happier with the Honorable Mention than I was with the problem. Although the Bristol and some technical elements in No.9 are novel, the key is so obvious that a solver will most likely miss the thematic tries.
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.


Bristol 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.
11. M. R. Vukcevich
4. HM Probleemblad 1970
Let me start with one of my own problems, No.11. This problem is the best illustration of many good and bad aspects of Bristols. After the key, 1.g4, white has the Bristol threat 2.Ra8, followed by 3.Qb8#. Black defends by bringing the Bb2 toward d6-square: 1... Rb3,Rc3,Bc3. These are answered by three Bristols from the other white R: 2.Re4, Re3, Re2, followed by 3.Qe5#.
Obviously, this piece gave the judge a serious headache: how many constructional faults and abuses can be justified by the artistic and thematic content? In my opinion, he erred horribly when he sided with tradition. Let me first point out the technical horrors, which must have been noticed by the judge. The white K and the Pd7 are there only to prevent the lateral motions of the white rooks. Furthermore, the Sg5 is there only to constrain the Sd2, which is needed only to prevent the B from reaching the f4- square.Now, let me switch to the artistic part: white does not need the Bristol from the threat. For example, remove the Rd8 and the Pb5 and Pc6. Then move the other white R to e6, the Pd7 to d6, and the Qe8 to e7. You saved three pieces, and everything works as before. Furthermore, you can massage this new position by moving everything up one rank and getting rid of Sd2 and Sg5. The economy improves, but the problem looses its soul. The Bristol from the threat is an integral part of the artistic complex. It took months to find this missing detail, and had it not been found, the problem would have not been published.
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.
12. N. Petrovic
Sahovski Problem 1949
#3 v6+10
Here white has to provide for the obvious flight-creating 1... f4. The immediate Bristol try 1.Rc1? fails because white is in Zugzwang after 1... g2!. The solution is the hesitatingBristol: 1.Rc3!! g2 2.Rc1! f4 3.Qc2#. The purity of the Bristol has been abandoned, the R acts laterally: 1... f4 2.R:g3+ hg3 3.Qc2#. This was the only impure line clearance by Petrovic. His later Bristols and Loyds were thematically pure.
I also adhered to the purity for the many more years, as exemplified by the extended Bristol in No.13.
13. M. R. Vukcevich
1.Pr. Die Schwalbe 1971
#3 v11+11
As in Petrovic's problem, if white plays immediately 1.Rh1?, he can answer 1... Bc2 with 2.Qg1#. However, after 1... cb4! he is in Zugzwang. The solution is 1.Rf1! cb4 2.Rh1! Bc2 3.Qg1#. The difference between this and Petrovic's hesitating Bristol is the additional thematic variation: 1... Bc2 2.Qe1 with 3.Qf2#. This combination had never before been shown in a threemover, and the judge obviously appreciated the artistic achievement. Same as myself, he has been brought up in the spirit of the German School.
14. A. Kuznecov
1.Pr. Ukrainian Champ. 1954
Meanwhile, the Russians had very little patience with purity of purpose. This modernization resulted in some beautiful pieces, composed as far back as the late 40's. In No.14Kuznecov shows two impure Bristols, where white queen is the front piece.

After 1.Bh7, the threat is 2.Re4+ B:e4 3.Se2#. The thematic variations are: 1... Q:h4 2.Qh6+ Bg5 3.Rf6#, and 1... R:g3 2.Qf2+ Raf3 3.Be3#. A beautiful blend of two strange line clearances and four pins.
15. L. Loshinsky and

"64" 1961
In No.15 by Loshinsky and Chepizni there are black and white Bristols.

After 1.Scd5, white threatens 2.Rf5+ B:f5 3.f4#. Black defends by clearing the line for his Q: 1... Bf5, Be6, Bd7. White answers with a Bristol of his own: 2.Rc4, Rc6, Rc7. Finally, after the longest black Bristol, white R goes sidewise: 1... Bc8 2.Rg2. This incredibly good problem was completely ignored by the conservative judge.
16. M. R. Vukcevich
3.Pr. Mat 1982
Shown in No.16 is my first impure clearence: two changed variations with a real and virtual Bristol.

In the set position, there are Bristol answers to 1... Rc1, Rb1 2.Bc4, Bb3. After the key 1.Qh8, white gives up one Bristol for another, and threatens 2.Bd4 3.Qe5#. The moves from the set are now answered by the new Bristol: 1... Rc1,Rb1 2.Bc3,Bb2. All of the clearances are impure, because the front piece interferes with the R.
Unfortunately, while a step in the right direction, the last problem had a very limited strategic content. The next problem takes care of that. No.17 was made especially for the Stosic Memorial Tournament, and is a strongly symbolic problem. But, let us not sidetrack. We may differ on the definition of symbolism.
17. M. R. Vukcevich
1.Pr. Stosic Memorial 1982
The key, 1.Qc7, threatens 2.Rc4+. After the selfpinning defenses, 1... R:d3, B:d3, white opens up the Bristols and creates two Nowotny intersections: 2.Rc2!,Bg3! B:c2,R:g3 3.Qc3,Qf4#. The mates are on pinned pieces, which are also parts of the Treffpunkt in the complementary variations of the Nowotny crossings: 1... R:d3,B:d3 2.Rc2,Bg3 R:c2,B:g3 3.R:d3#. The number of strategic elements in these two variations is probably higher than in any of my threemovers.
Abandoning thematic purity freed the imagination, although it did not always improved the art. Among many experiments, No.18 is an interesting case which, I am sure, deserves more, and better, exploitation.
18. M. R. Vukcevich
M. Chess Life 1986
The Nowotny key 1.Qg4 also creates two Bristols. After the Nowotny answers 1... B:g4, R:g4 follow the quiet but prosaic 2.Rd4,Bf5 with 3.Rc7#. More interesting is what happens after the Nowotny pieces go sidewise and remove the rear-guard on the white Q: 1... Rh8,Bf1 2.Rc4+,Bd7+ Kd5 3.Qd4,Qe6#. The Bristols are completely impure, but the whole setup with Nowotny and the rear-guards is very original. It is unfortunate that the artistic impact of this problem is mediocre, which explains why such a good idea ended at the bottom of the award.
The next example, No.19, is a more modern blend: a Bristol with a cycle of the second and third moves by the back piece.
19. M. R. Vukcevich
USPB 1992
After the Bristol key 1.Rc8! the threat is impure, but thematic: 2.Sf6+ Kd6 3.Qc7#. In the three main variations the Bristol Q oscillates in a cycle on the squares c4, c5 and c6: 1... e3,Q:e7,e5 2.Qc5+,Qc4+,Qc6+ Ke4,Kd6,Kd4 3.Qc4,Qc6,Qc5#. Or, 2.A/B/C, 3.B/C/A. It is a technical accomplishment to create a cycle within the constrains of the Bristol theme. But, again, the artistic side is not completely satisfactory. Bristols appear not to blend particularly well with cycles.
Although the last two modernizations were not entirely successful, they are opening new trials for future adventures. In particular, the blending of Bristols with other line themes, such as Nowotny, appears very natural and promising.


The 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.
20. T. Siaperas
Sah 1949
Again, Siaperas set some of the earliest standards. In No.20he demonstrates the consecutive Bristols. There is only one thematic line: 1.Rh2! K:d5 2.Ra1! Ke4 3.Qa2 Kf3 4.Qg2#.
Very simple, but it inspired another form of the consecutive Bristol, shown in No.21. This is a more complex affair, in strategy and construction.
21. M. R. Vukcevich
2.Pr. Problem 1969
After 1.Ra1! the threat is a consecutive Bristol: 2.Qa2 B:d2 3.Bd5! 4.Qc4#. After the defense 1... Bf6, the same white R starts the second Bristol in another dimension: 2.Rh1! Q:d2 3.Qa1+ Qc3 4.Qg1#. Because the pieces move in two dimensions, Petrovic suggested the name planar Bristol for this clearence.
22. K. H. Hannemann
Svenska Dagbladet 1925
Another way to double the work of the two Bristol pieces is to have them clear each others' path by returning to their original positions. This was introduced by Hannemann in No.22.

White has to destroy the black B and retain the Q. When that happens, black will have to play K:g2, and the Q will mate on the a8-h1 diagonal. The solution is 1.Qb1! Bb2 2.R:b2 K:g2 3.Rb8! Kh1 4.Qb7#. This is a true and thematically pure four-move maneuver.
23. I. Soroka and
R. Fedorovich

Schach 1979
To improve the construction, Soroka and Fedorovich used five moves in No.23.

After 1.Bh1! g4 2.Qg2 white forces 2... a5, upon which the pieces return: 3.Qa8!, 4.Bb7, 5.Qa6#. Note that the theme in this problem does not have the purity of purpose shown in Hannemann's piece. However, because of the open construction, it is much more rewarding experience for a solver.
A different four-move Bristol maneuver is to have the forward piece clear the line, then return back, and then clear the line again. I experimented with this, and even had a modest tournament success. However, the four-move maneuvers should be tried in fivemovers. In fourmovers they usually led to a single thematic line. Single-line fourmovers were acceptable four decades ago. Today, even some ninemovers have more than one thematic variation.Siaperas also seriously explored dueling white and black Bristols. His most complex composition is shown in No.24.
24. T. Siaperas
2.Pr. Pauli Memorial 1949
After a poor key, 1.Qf2, white has two Bristol threats. In each of the two thematic variations black defeats one Bristol and nearly defends against the other. However, in executing his Bristols, black ends making double critical moves: 1... Bf1! 2.Bb6! Qe2 3.Rd3+ ed3 4.c4# and 1... Rg6! 2.Bc5! Qf6 3.Be6+ fe6 4.Rd7#. This is an astonishing conception that forces you to forget that many of the 27 pieces are poorly employed.
Siaperas called the black theme the Bristol-Nowotny. He also suggested that the Bristol-Grimshaw, where white does not sacrifice a piece at the critical square, is worth exploring.
25. M. R. Vukcevich
3.Pr. Die Schwalbe 1971
Another type of dueling Bristols is shown in No.25. This problem doubles the content of the old Kohtz and Kockelkorn problem shown earlier. After 1.Ba8! white threatens 2.Qb7. When black defends with 1... Rh1! white cannot play 2.Qb7? because upon 2... Qh2 he ends in Zugzwang with his B immobilized on a8. Instead, white plays 2.Qc6! threatening 3.Qa6 Sb5 4.Qa2#. When black again defends with 2... Qh2 white finally plays 3.Qb7! and now black is in Zugzwang with his R immobilized on h1.
Before I leave the orthodox problems, let me point out that in moremovers the future is not only in complex or dueling Bristols. The classical white Bristol is not well explored in longer problems. A clear example of a novel, but still classical maneuver is shown in No.26.
26. M. R. Vukcevich
1.Pr. Schach-Echo 1982
After 1.Qh1! white threatens 2.f3+ Sd:f3,Sf:f3 3.Qb1+,Qh7+ K:e3 4.Qd3#. The thematic defenses are 1... Rb5 and 1... Bb5. This is a pair of self-obstructions, which allow white to create from scratch one of the two Bristols. After 1... Rb5 2.Rg1+! Sdf3 3.Ra1!! and 4.Qb1# because black can not defend with 3... Bb5. After 1... Bb5 2.Rh2+! Sgf3 3.Rh8!! and 4.Qh7# because now black does not have 3... Rb5.
It is not possible to guess how many completely new forms of Bristols exist in moremovers. The whole area is poorly explored jungle, full of animals of unknown size, all descendants of a simple two-move cell. Extending the number of moves does not necessarily violate the law of the economy of time. All problems shown in this section extend the two-move Bristols into true four-move maneuvers. But even if we were to violate that law, would it bother us? Aren't we the lawless bunch who already violated the law of purpose?


Bristols 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.
27. M. R. Vukcevich
2.Pr. The Problemist 1971
It appears that my No.27 opened the gate. After 1.Qg3! the threat is 2.Qe5+ B:e5 3.Bd3+ Q:d3#. The thematic defenses create black Bristols which white forces to open: 1... Qh8 2.d3+ Bb2 3.Sc3+ Q:c3# and 1... B:g6 2.d4+ Bc2 3.Qd3+ Q:d3#.
28. M. Stosic
1.Pr. Probleemblad 1972
A similar mechanism operates in Stosic's No.28.

After 1.Re8! the threat is 2.Rf8+ Ke5 3.Qd6+ cd6#. Black defends by moving his Q from b6, which creates two black Bristols: 1... Qa3 2.Se4+ Rf3 3.Se3+ Q:e3# and 1... Qa3 2.Sd3+ Rf4 3.Sd4+ Q:d4#.Since the Bristols are forced by white, they do not have the orthodox purity of purpose. However, I do not know of anyone who would object on this basis.
As in the orthodox problems, increasing the number of moves allows new and exciting effects. No.29 is a recent example.
29. M. R. Vukcevich
1.Pr. USPB 1990
After 1.S:g4! the threat is 2.Sf2+ B:f2 3.Q:b5+. There are two Bristol variations with the same blend of elements: the opening of Bristol lines, the white king battery and the forcing of the Bristols: 1... Qh1 2.Be2+ fe2+ 3.Ke5+ Bd5 4.Qe4+ Q:e4# and 1... Qh2 2.Re3+ fe3 3.Ke6+ Bd6 4.Se5+ Q:e5#. These two lines are complemented by two variations in which the black pawn batteries mate: 1... f2+ 2.Ke5+ Bd5 3.Qd4+ B:d4 4.Re3+ fe3# and 1... Ra7 2.Sf2+ B:f2 3.Qd4+ B:d4 4.Be2+ fe2#.
There are also possibilities for white Bristols in selfmates. Decades ago, Siaperas and I took refuge in selfmates whenever our white Bristols reached the level of complexity at which they were hopelessly cooked in their orthodox versions. However, there are also purely artistic reasons for selfmates with white Bristols. In No.30 white unravels the black batteries in the north-east corner by exploding the Bristols on the west side of the board.
30. M. R. Vukcevich
1.Pr. USPB 1988
After the key, 1.Sa6, the Bristol variations are: 1... K:a6 2.Ra7+ Kb5 3.Qb7+ R:b7# and 1... Ka4 2.Bb3+ Kb5 3.Qc4+ B:c4#. In the complementary variation, 1... g4(h3), the white Q steps sidewise, and the two front pieces force the black batteries: 2.Qf1+ K:c6,Ka4 3.Rc7+,Bb3+ R:c7,B:b3#.
I choose this problem to end the article because it has no theoretical significance - it is the spiritual brother of my orthodox threemover 18, it is impure and unsophisticated. However, it was composed to give solvers visual pleasure, and in this sense it represents what is the best in all good Bristols.
[This post in Greek language].


vegetablebede said...

The link to Milan's article on Bristol's is broken. Replacing the url with matplus.net doesn't help.

Emmanuel Manolas said...

Thanks vegetablebede.
I have found the article and I have appended it to my post.
In a few days I will replace the chessboard images to be shown correctly.