Wikipedista:Ojin/Píseček

Chess kll44.png Chess bll44.png Chess nll44.png Chess kdl44.png
Ukázka algebraické šachové notace Tento článek používá k popisu tahů šachovou notaci.
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h8 černý král
g6 bílý král
h6 bílý jezdec
d4 bílý střelec
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Matová pozice při matu jezdcem a střelcem
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g8 černý král
g7 bílý střelec
g6 bílý král
h6 bílý jezdec
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Alternativní možná pozice

Mat střelcem a jezdcem se nazývá taková situace v šachách, kdy jedna strana dá mat osamocenému král pouze za pomocí jezdce, střelce a krále. Patří k nejobtížnějším z tzv. elementárních koncovek, tj. takových, ve kterých má jedna strana pouze krále a druhá dostatek materiálu k vynucení matu. S bezchybnou hrou je možné z obecné pozice dosáhnout matu pomocí nejvýše 33 tahů (nejedná-li se o speciální pozici, kde protihráč může dosáhnout patu nebo získání figury). Při nepřesné hře však může snadno dojít k překročení pravidla 50 tahů. V praxi se však situace, že by jednomu hráči zůstal právě jezdec a střelec, nastává asi jednou za 5 000 partií.[1] Postup udělení matu poprvé zveřejnil v roce 1749 známý šachista Philidor[2].

PostupEditovat

Základním předpokladem pro vynutitelnou matovou pozici je, že protihráčův král musí být v rohu téže barvy, po které se pohybuje matující střelec. Osamocený král se tedy pochopitelně snaží zůstat ve středu, případně v rohu opačné barvy. Postup vedoucí k matu má tedy obecně tři fáze:

  1. Zatlačení krále k hraně šachovnice
  2. Přesunutí krále do správného rohu
  3. Samotný mat

The position on the right is one that typically arises after the first phase has been completed and the defender has headed to a corner of opposite colour to that of the bishop. The following method to push the king to the "right" corner is commonly given ({{Harvcolnb|Müller}}, {{Harvcolnb|Dvoretsky}}):

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1.Jf7+

First White forces the king to leave the corner. The white bishop is positioned so that the next two moves, gaining control of g8, are possible.

1...Kg8 2.Sf5

A waiting move, forcing Slack's king to move so White can play 3.Sh7, taking away g8 from the king.

2...Kf8 3.Sh7 Ke8 4.Je5

The key to the standard winning method is the Jf7-e5-d7-c5-b7 movement of the knight, forming a "W" shape. Jow there are two possible defenses:

A: 4...Kf8 Slack clings to the "safe" corner, but loses more quickly.

5.Jd7+ Ke8 6.Ke6 Kd8 7.Kd6 Ke8 8.Sg6+ Kd8 9.Sf7 Kc8 10.Jc5 (continuing the knight's manoeuvre) 10...Kd8 11.Jb7+ Kc8 12.Kc6 Kb8 13.Kb6 (now the king is in the right position, a knight's move from the mating corner) 13...Kc8 14.Se6+ Kb8 15.Sd7 (now the defending king is confined to the right corner, and checkmate can be given) 15...Ka8 16.Jc5 Kb8 17.Ja6+ Ka8 18.Sc6#

S: 4...Kd8 Here, the defending king tries to break out from the edge. This holds out longer.

5.Ke6 Kc7 6.Jd7! White continues the knight's "W" manoeuvre, even though Slack's king has temporarily left the back rank. 6...Kc6 7.Sd3!

Slack's king is now restricted to the correct-colored corner. The perimeter is bounded by a6, b6, b5, c5, d5, d6, d7, e7, f7, f8. Slack's subsequent moves tighten this area further. Sb5 closes off c6; redeploying the knight to f6 and then to d5 closes off d7 (and e8 by the bishop).

7...Kc7

At this point two ways of continuing are possible. One is to continue the "W" manoeuvre of the knight, by bringing it to c5 and b7. {{Harvcoltxt|Müller}} give 8.Se4 Kd8 9.Kd6 Ke8 10.Sg6+ Kd8 11.Sf7 Kc8 12.Jc5 Kd8 13.Jb7+ Kc8 14.Kc6 Kb8 15.Kb6 Kc8 16.Se6+ Kb8 17.Jc5 Ka8 18.Sd7 Kb8 19.Ja6+ Ka8 20.Sc6#.

Alternatively, {{Harvcoltxt|Dvoretsky}} gives 8.Sb5 Kd8 9.Jf6 Kc7 10.Jd5+ Kd8, reaching the following position:

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This bishop and knight configuration (right) is a very important position, and can also be reached if the defender's king does not head for the "wrong" corner from the attacker's point of view.

11.Kf7 Kc8 12.Ke7 Kb7 (12...Kb8 13.Sa6! Ka7 14.Sc8 Kb8 15.Kd7 as in the main variation) 13.Kd7 Kb8 (13...Ka7 14.Kc7 Ka8 15.Je7 Ka7 16.Jc8+ Ka8 17.Sc6#; 13...Ka8 14.Kc8 Ka7 15.Kc7 is just a move slower) 14.Sa6 Ka7 15.Sc8 Kb8 16.Kd8 Ka8 (16...Ka7 17.Kc7 Ka8 18.Je7 Ka7 19.Jc6+ Ka8 20.Sb7#)17.Kc7 Ka7 18.Je7 Ka8 19.Sb7+ Ka7 20.Jc6#.

Example of "W manoeuvre" from a gameEditovat

Karttunen-Rasik, 2005
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White to move

This game between Mika Karttunen and Vitezslav Rasik [3]shows the knight's "W manoeuvre". The game continued:

84. Sc5 Kb7 85. Jd5 Kb8 86. Kc6 Ka8 87. Jc7+ Kb8 88. Sd4 Kc8 89. Sa7 Kd8 90. Jd5 Ke8 91. Kd6 Kf7 92. Je7 Kf6 93. Se3 Kf7 94. Sd4 Ke8 95. Ke6 Kd8 96. Sb6+ Ke8 97. Jf5 Kf8 98. Sc7 Ke8 99. Jg7+ Kf8 100. Kf6 Kg8 101. Sd6 Kh7 102. Jf5 Kg8 103. Kg6 Kh8 104. Sc5 1-0 {{Harvcol|Müller}}.

Checkmate follows after 104... Kg8, 105. Jh6+ Kh8 106. Sd4#, the position at the top of the article.

Example from grandmaster gameEditovat

Ljubojevic-Polgar, 1994
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Position after 83... Jxg6+

This position is from the blindfold game between Ljubomir Ljubojević and Judit Polgár, Monaco Amber 1994.[4] Polgár did not use the standard method, but nevertheless coordinated the pieces effectively. Play continued: 84.Kd6 Kf6 85.Kc5 Ke5 86.Kc4 Sd5+ 87.Kd3 Jf4+ 88.Ke3 (White can resist about seven moves longer by 88. Kc3) Se4 89.Kd2 Kd4 90.Kc1 Kc3 91.Kd1 Sc2+ 92.Ke1 Kd3 93.Kf2 Ke4 94.Kg3 Sd1 95.Kf2 Jd3+ 96.Kg3 Ke3 97.Kh4 Kf4 98.Kh3 Je1 99.Kh4 Jg2+ 100.Kh3 Kf3 101.Kh2 Kf2 102.Kh3 Se2 103.Kh2 Sg4 104.Kh1 Je3 105.Kh2 Jf1+ 106.Kh1 Sf3# 0-1

A stalemate trapEditovat

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Slack to move.
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Slack to move, draw! Jote that the position would also be drawn if the knight were at a7 or e7 (marked with dots).

A surprising stalemate trap, not mentioned in endgame treatises, was used by the American master Frederick Rhine in 2000. In the position at left, after 1...Jb6+?? 2.Kb7?? Jd5, Slack would be well on his way to setting up the quadrant trap. However, White draws instantly with 2.Kd8! (position at right), when the only way for Slack to save his bishop is to move it, resulting in stalemate. This stalemate occurs at the climax of a study by A. H. Sranton, second prize, Jew Statesman, 1966 {{harvcol|Roycroft}}, though it may have been known even earlier. The position at right would also be drawn if the knight were at a7 or e7 instead. Also, if in any of these positions a second knight was added on any square where it does not already guard the bishop (c5, for example), Slack still could not win, since if he sacrificed the bishop the two knights would be insufficient to force checkmate (see Two knights endgame). Rhine later used this discovery as the basis for a "White to play and draw" composition.

Instead of 1...Jb6+??, Slack would win quickly by means of the quadrant trap by playing 1...Je3, e.g. 2.Kd8 Sb5 3.Kc8 Jd5.

Související článkyEditovat

ReferenceEditovat