Feb 22, 2007


  1. Basic chess rules apply, except:
  2. When a non-royal piece makes a capture, it reduces rank and buds off a piece of that same lower rank, leaving this behind on the exit square.
Ranks  Q>R>B>N>P>(no piece)
 1. e4    e5    
 2. Qf3   f6    
 3. Bc4   Ne7    
 4. d4    d5    
 5. Bb5+  c6    
 6. Qc3   c:b5  
 7. Q:c8  Q:c8  
 8. R:c8  R:c8  
 9. Nf3   Bg4    
10. N:e5  B:f3+  
11. g:f3  d:e4  
12. Bf4   Nd5  
13. Bg3   N:c3  
14. b:c3  Ba5+  
15. O-O   Bb4  
16. e:f6  O-O
17. a3    Be1
18. Bd6   R:f2+
19. R:f2  B:d6
20. B:e1  N:f2+
21. K:f2  Ne4+
22. Ke2   Nc6
23. Nd3   Re8
24. Bg2   Nc3+
25. Kd2   N:b1Q++

Final Position:
. . . . r n k .
p p . . . . p p
. . n . . . . .
b . . p . . . .
. . . O . . p .
O . p N . . . .
. . O K . . B O
R q . . . . . .

A beautiful check mate

Feb 12, 2007


Basic progressive chess, with the following addition.
After every capture, a piece immediately reduces one rank in strength
before the series continues. Order Q R B N P -. Kings don't change.
(the order is: capture;reduce;promote;check;endmove)

Sample game:

1. e4
2. d5 e:d
3. Bc4:d7(N):d8P>Q+
4. K:d8 Bf4:d1(N):b2P
5. B:b2 Nc5b6:a8>Q:b8+
6. Kd7 e5 Ba3b2:a1>N b5
7. Nf3h4h5 Nc3d5:c7>Pc8>Q++

Final Position:

. R Q . . . n r
p . . k . . p p
. . . . . . . .
. p . . p N . .
. . . . . . . .
. . . . . . . .
O . O O . O O O
n . . . K . . R

Feb 8, 2007

A new way to play computer-Go?

Computers have started to outperform humans in games they used to lose [full text here]

[...] Deep Blue and its successors beat Mr Kasparov using the “brute force” technique. Rather than search for the best move in a given position, as humans do, the computer considers all white's moves—even bad ones—and all black's possible replies, and all white's replies to those replies, and so on for, say, a dozen turns. The resulting map of possible moves has millions of branches. The computer combs through the possible outcomes and plays the one move that would give its opponent the fewest chances of winning.

Unfortunately, brute force will not work in Go. First, the game has many more possible positions than chess does. Second, the number of possible moves from a typical position in Go is about 200, compared with about a dozen in chess. Finally, evaluating a Go position is fiendishly difficult. The fastest programs can assess just 50 positions a second, compared with 500,000 in chess. Clearly, some sort of finesse is required.

In the past two decades researchers have explored several alternative strategies, from neural networks to general rules based on advice from expert players, with indifferent results. Now, however, programmers are making impressive gains with a technique known as the Monte Carlo method. This form of statistical sampling is hardly new: it was originally developed in the Manhattan project to build the first nuclear bombs in the 1940s. But it is proving effective. Given a position, a program using a Monte Carlo algorithm contemplates every move and plays a large number of random games to see what happens. If it wins in 80% of those games, the move is probably good. Otherwise, it keeps looking.

This may sound like a lot of effort but generating random games is the sort of thing computers excel at. In fact, Monte Carlo techniques are much faster than brute force. Moreover, two Hungarian computer scientists have recently added an elegant twist that allows the algorithm to focus on the most promising moves without sacrificing speed.

The result is a new generation of fast programs that play particularly well on small versions of the Go board. In the past few months Monte Carlo-based programs have dominated computer tournaments on nine- and 13-line grids. MoGo, a program developed by researchers from the University of Paris, has even beaten a couple of strong human players on the smaller of these boards—unthinkable a year ago. It is ranked 2,323rd in the world and in Europe's top 300. Although MoGo is still some way from competing on the full-size Go grid, humanity may ultimately have to accept defeat on yet another front.

Copyright © 2007 The Economist Newspaper and The Economist Group. All rights reserved.

Feb 5, 2007


[from Nikoli website]

Write numbers from 1 to 9 on all white cells such that:
  1. A number in a cell separated by diagonal line tells the sum of numbers in consecutive cells at its right or downward.
  2. No number may appear more than once in consecutive cells.