Tuesday, February 06, 2007
5/1001
Even though I haven't finished 1001 I know I eventually will, and I feel like I am already coming around full circle.Whenever I look at the composed problems at the end of 1001 I go into molasses mode. They are clever, cursed little buggers, and I am still getting the solutions only fifty percent of the time. I occasionally flip back to the beginning of the book and do some normal checkmates. Nothing quite like sacrificing a piece or two for checkmate :-). Here is a great example (number 5):
I think this problem is one of the best in the book, and a clear case of simultaneous advantage. Although it is in the Queen sacrifice section, it really is a Rook sacrifice problem.
The first time I saw this problem was several years ago. I could not solve it and took me quite a while to understand the solution. I tried piecing it together by looking at c8. The c8 square appeared to be attacked twice by White and guarded three times by Black, a situation that does not usually lead to checkmate. I thought the answer had something to do with the fact that Rc8! absolutely pinned Black's Queen and simultaneously threatened Qxd8#.
Appearances were deceiving me and now I see an important advantage White has: Black's Queen is a tied down defender, unable to capture anything on c8 because of White's Qe7# checkmate threat. Rather than looking at c8 I look at d8, appreciating that Rc8! outnumbers Black's Queen with three attackers when it is protected only twice (1 of which is x-ray protection from the Black Rook on a1 after Rc8). If you still not see the answer, picture the board after Rc8! Rxc8 {maintaining protection of the Queen on d8} Rxc8 Bxc8. At this point the Black Queen is clearly outnumbered and Qxd8# is the result. Great problem, eh?
Sunday, January 21, 2007
911/1001
The first time through this "checkmate" problem I made the same mistake that the author made: 1. Rf8+ Rxf8 2. Bc4+ Kg7 3. e8=N+ Rxe8 4. Qf7#. I had just seen an underpromotion and was thinking along those lines (no pun intended).
That was a month ago. I went through it again last week when I was taking a break from the composed checkmates. Seeing this problem again I was stumped. I thought Rf8+ Qxf8! busts the variation, and I was looking to sacrifice the pawn but did not see that either. Fritz confirmed it - not a checkmate problem. Something about it seemed intriguing though. Take a look at this alternate position:
Now e8=Q+ Rxe8 Rc7 essentially forks c1 and f7, threatening mate with either the Bishop or Queen. The awful Qc1+ Rxc1 is the only reply that isn't a quick mate. I don't know of any pawn promotion/clearance sacrifices that are followed by forking two squares with a Rook.
Wednesday, January 10, 2007
Composed Checkmates
Well, worse has come to worse, and I have started on that last infernal section of the book. No circles on this section - I am just going through it once and repeating it once. I am pleasantly surprised to find I truly have improved from before starting the TASC circles; rather than never getting the right answer in 5-10 minutes, I am solving them about 50% of the time in that amount of time. Unfortunately I always seem to leave out one or more defensive variations, and that tells me I have some fundamental calculation blindspots to work on.
They still strike me as unnatural and overly clever, but solving them is a chess workout.
In order to keep things balanced I review some ordinary checkmates fairly regularly. One thing that is hitting home stronger now is how beneficial solving "upside-down" checkmates are (i.e. normal board but with Black to move). This is what I am doing before each move anyway, so why not practice it. Before the TASC circles it was tough to do, and now I realize it is important to do.
Wednesday, January 03, 2007
Finished Circles 5-7
Saturday, December 30, 2006
"Which Tactic is This?" Revisited.
White to Move
2k1q3/p2r1p2/P7/Q6B/8/Kp2r3/8/6R1 w - - 0 1
Note: if you want to solve this checkmate problem first, better stop reading now!
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I was stuck on this one for awhile and still did not get it right. The two easier variations are 1.Rc1+ Rc7?? and 1.Rc1+ Rc3. I won't comment on those - they are much more forced. I never could get through the 1.Rc1+ Kb8 variation completely on my own. After looking up the answer and working through it in subsequent circles, I began to appreciate this problem more.
Seeing that White's Queen could give check on b4 was alot different than giving check b5 was pretty easy. The key to the difficulty seems to be the c8 square. First it's where Black's King is, then Black is guarding c8 more times than it is attacked, then Black is guarding c8 once as it is being attacked once. At the same time the Black King is stuck in the corner, walking into a strange sort of back rank checkmate threat.
After 1.Rc1+ Kb8 2.Qb4+ Ka8 3.Bf3!+ Rxf3
I am now beginning to think I left something out of my Simultaneous Advantage post: tying down defenders. That is similar to immobilizing defenders, although they still have some movement available to them. Here is a simplified analysis of the above position.
Preexisting advantages:
- All of Black's King's flight squares have been removed.
- Black's Queen is tied down to the eighth rank to defend against the back rank checkmate threat Rc8#.
- Black's Rook on c7 is tied down to the seventh rank to defend against Qb7#.
On Qe4! Black gets some advantages from the move:
- Moving into capture - White's Queen is unprotected on e4
- Giving a King flight square - b8
White gets advantages which are terminal for Black:
- Forcing with check - this also implies "preventing counterattack" on White's King
- Threatening capture - Black's unprotected Queen is threatened with Qxe8+
- Removing King's flight square - a8
- Resulting checkmate threat - ...Kb8 Qxe8+ Rd8 Qxd8#
Defensive options:
Rook (on d7) to b7 walks into mate in one.
...Rb7 Qxb7#
Rook (on d7) to d5 walks into mate in two.
...Rd5 Qxe8+ Rd8 Qxd8#
Similarly Kb7 walks into mate in two.
...Kb7 Qxe8+ Rd8 Qxd8#
Queen takes Queen on e4 walks into the back rank mate in one.
...Qxe4 5. Rc8#
So what tactic (besides the fork aspect) is going on in the move Qe4? It seems to me as a special case of attacking the defender: a enprise attack on a tied down defender. Although Black's Queen is hanging, I believe a tied down defender essentially is equivalent to a hanging piece. Here's an example:
White to Move
Qb7! forks both Black Queens. Although they defend each other, the Black Queens cannot simultaneously defend against the back-rank mate threat and capture White's Queen.
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I am getting a bit annoyed with this new blogger editor as it keeps adding lines, especially in bulleted sentences.**rolls eyes**. Perhaps WordPress is in my future...
Finished circle 4, and picking up some speed.
Happy New Year Everyone!
Circle 3 Complete
I have found two wrong answers, 513 and 524. The mating idea was right, it just took more moves.
Wednesday, December 27, 2006
Circle 2 Complete
Sunday, December 24, 2006
Circle 1 Complete
As I circle through my checkmate problems, I have begun to categorize the themes that come up in the checkmates that I often get wrong.
- Sacrifice not on the initial move
- Quiet moves, especially not on the initial move
- Opening lines to take away opponent's King flight squares
- Interference, forcing opponent's pieces onto his own King's flight squares, especially not on the initial move
- Overworked Defenders who are not overworked on or after the initial move
This leaves out taking extra moves to achieve mate, using squares beyond a1 through h8, or instantaneously promoting all of my pieces to Queens.
I am working on a universal definition of the weakest part of my chess game. So far I have two possibilities: either the part of my game that I am scrutinizing at this time or the more straightforward all parts of my game are very, very weak. This definition seems to apply to the majority of chess players, players at all rating levels as well. At least how they describe themselves ;-).
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I wanted to put in a good word for GM Eugene Perelshteyn's French Defense opening lecture on chessfm. It was immensely accessible and well thought out. Although I never play either side of that opening, it didn't matter. I have not read his related books, but I gather they are quite good for beginner through intermediate level players.
These lectures are one of the biggest reason I joined the ICC - to support them to keep doing it =). I hope to see more.
Wednesday, December 20, 2006
Starting Circle 1
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Bb5+ c6 6. Qe2 Qe7 7. Bd3 Nc5 8. Qxe7+ Bxe7 9. O-O Nxd3 10. cxd3 O-O 11. b3 Bf6 12. Nc3 Bf5 13. Ba3 Rd8 14. d4 Na6 15. Rfe1 b5 16. Bb2 Nb4 17. Rad1 Nd3 {White resigns} 0-1
