[blind-chess] Re: Spoiler Alert Problem WAC027
- From: "R Dinger" <rrdinger@xxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Thu, 26 Aug 2010 19:06:52 -0700
Hello Paul, Thank you for another excellent problem analysis and discussion.Your notion of an x-ray attack is an interesting concept and a valuable lesson.
I was tempted by the royal fork in this problem, but afraid of the Black Rook guarding f7. Your thorough analysis of all Black's mating threats clearly shows I was on a wrong track with that line.
Regards, Richard----- Original Message ----- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
To: <blind-chess@xxxxxxxxxxxxx> Sent: Wednesday, August 25, 2010 9:30 PM Subject: [blind-chess] Spoiler Alert Problem WAC027
.Hello all, .I assume that as you are reading this, that you have had a go at the problem and wish to explore my thoughts on problem WAC027, before the official publication of the solution.This posting is divided into various parts. You can jump to the headings of the sections by search/find for **, that is a pair of asterisks. Thus if the heading is not particularly of interest to you, then jump to the next section. In this way, you can avoid accidentally coming across some part of my contribution which may spoil it for you. ** Positional evaluation of the problem . From the white perspective.White is 3 pawns down, any thoughts of surviving in an endgame should be totally ignored, the middle game must continue for as long as possible. The knight is well placed on e5, it can not be dislodged by a pawn, and the only minor piece to challenge it, without black giving up material, is the black knight on g7, and there is no simple route for the black knight to take to put in a challenge. The heavy pieces, queen and rooks, are somewhat passively placed. There are no dynamic pawn moves. Finally, the king is rather short of pieces to protect him, thankfully, he has some pawn protection. From the black perspective.Three pawns up, if there is nothing better, seek exchanges of queens, followed by as many of the pieces as can be arranged. The heavy pieces, fantastic. This doubling of the rooks on the 7th rank is one of the best middle or endgame arrangements that rooks can achieve. The queen is also joining in the attack on the white king, the square g2 is under heavy pressure. The knight is poorly placed on g7, the kindest thing we could say about it, is it has great unrealised potential .An ideal outpost for it would be e4, but that takes 3 moves. There are no pawn weaknesses. The king is tucked away in the corner, which is sometimes a blessing and sometimes a curse.. ** Hints section . There are 4 hints to assist in trying to solve this problem . ** Hint 1, to finding the key move . A saying, invented to assist understanding of strategy and tactics, is: "The power of the pin is to paralyse . ** Hint 2, to finding the key move .I apologise if that last hint caused confusion. There is most definitely a pin in the position. If I may paraphrase one of those Star Trek quips, this time from Spock, which have crept into the language:"It's a pin Jim, but not as we know it" . ** Hint 3, to finding the key move .So Spock, it's a pin, but not as we know it. Illogical Spock, surely, a pin occurs when an attacking unit prevents a defending unit from moving, either because a move would be illegal, or lose material, right? So, where is the pin?. ** 4th and final hint, to finding the key move ..If Spock were here to respond, he may retort: "Your concept is correct but limited. It is equally possible for a piece to be pinned to a vacant square, Jim". ** My proposed solution to problem WAC027 .So Spock reckons there is a piece pinned to a vacant square. The only such piece is the rook on f2. White wins with1. Qf8+ Rxf8 2. Rxf8 mate .The white rook had an x-ray attack against the f8 square. Just because a file appears to be blocked, does not mean it is. X-ray attacks become possible when two similar-value opposing pieces, in this case rooks, are lined up so that one apparently restricts the power of the other, by blocking it from moving.. ** Tactical evaluation of the problem .Of the 4 problems I have analysed, this is the most complex starting position..At some point when analysing tactical positions, one should take some time to work out what threats the opponent has. This lets you know what may happen once any forcing lines you are analysing fizzle out.If it were black to move, then 1. ... Qxg2 is mate. , there are also 3 mates in 2. The first is, 1. ... Rxg2+ 2. Kh1 Rxh2 is mate, which demonstrates the power of 2 rooks doubled on the 7th rank.The second is, 1. ... Rxf1+ 2. Kxf1 Qxc1 is mate. The third is, 1. ... Rxf1+ 2. Rxf1 Qxg2 is mate .You may wish to work out if black to move, can still win if the black queen were removed from the board.The answer is yes, as follows:1. ... Rxg2+ 2. Kh1 Rxh2+ 3. Kg1 Rbg2 mate. This fully demonstrates one of the most powerful threats when a pair of rooks are doubled on the 7th rank. For this mating pattern to be successful, it requires that a defending rook must be located on the square on which a bishop sits at the start of the game, that is f1 to mate white here..So, now you know what black will do, given half a chance. Now for some analysis for white. The defensive 1 Qh3 will get precisely what it deserves. That is:1. ... Qxg2+ 2. Qxg2+ Rxg2+, leading to mate in 2 moves, as shown already . So, perhaps white can relieve the pressure with captures. Try,1. Rxf2, but after 1. ... Qxc1+ 2. Rf1, and this will quickly end in a forced draw. Black plays 2. ... Rg2+, and white is surely losing a queen? Yes, 3. Kxg2 Qxa3, and the black queen has neatly guarded that vulnerable square, f8, where the back-rank mate occurred in my proposed solution. So, where is this draw for white? White takes advantage of the curious black knight and pawn configuration with, 4. Nf7+ Kg8 5. Nh6+, and the black king can not move to the f-file, so 6. ... Kh8 is forced. Now, 7. Nf7+ is repeating moves, white has a perpetual check.For completeness, white could try 1. Qxb2, hoping for a massive blunder by black. Should black take the queen, then white has rf8 mate. Of course, black would play 1. ... Qxg2 mate. There is one last try for white, and it wins the black queen, by:1.Nf7+ Kg8 2. Nxg5, but has this been considered in some way already? Yes, remember the tactical analysis of the threats black had in the starting position? As an exercise, the black queen was removed from the board,and yet, there was still a threat of mate from those rooks. ** Alarm Bells .Firstly, the black king location. When one has no rooks on your back-rank, then be aware of being mated if your king has no flight squares.Secondly,this problem is about pinning to a vacant square, combined with the x-ray attack. The black rook on f2 shields f8 from the white rook on f1, but the white queen can drag the black rook away from the square where it protected f8. The black rook appeared to block the power of the white rook to move forward. However, it was an illusion, courtesy of Her Majesty on a3Paul Benson.. -----Original Message----- From: R Dinger - Email Address: rrdinger@xxxxxxxxxx Sent On: 25/08/2010 17:20 Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx Subject: [blind-chess] Problem WAC027 Good Morning Puzzlers, This problem is from Mario Lang's puzzle web page at http://delysid.org/chess/epd.cgi and is reported to be from Fred Reinfield's book "Win At Chess" 1958. Problem WAC027 White to move FEN Problem Setup: 7k/ pp4np/ 2p3p1/ 3pN1q1/ 3P4/ Q7/ 1r3rPP/ 2R2RK1 w - - 0 1 Short Algebraic Problem Setup: White: Kg1, Qa3, Rc1, Rf1, Ne5, Pd4, Pg2, Ph2 Black: Kh8, Qg5, Rb2, Rf2, Ng7, Pa7, Pb7, Pc6, Pd5, Pg6, Ph7
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- [blind-chess] Spoiler Alert Problem WAC027
- From: Paul Benson
- [blind-chess] Spoiler Alert Problem WAC027