From: Colin Paul Adams COLINA DEMON CO UK> Date: 21 feb 1999 Subject: Solution to D29 (long) >>>>> "Steve" == Steve Evans NETSPACE NET AU> writes: Steve> The 38 move solution is: There is at least (I haven't seen others, so far), one extra side variation that should be included for the complete solution. But my main reason for continuing this thread, is I though that people might be interested in the process by which Steve and I edged towards this solution. For these reasons: (1) It might encourage others to have a go at the problems again (the lesson is - do not be in a hurry to give up on "insoluble2 problems (2) The co-operation between Men and Machines, that we found necessary to solve this problem, is (I think) of interest in itself (and re-inforces point (3)). (Steve will probably have to add some comments here, as I don't know exactly when he used his program to help). (3) In order to appreciate just how good a problem this is (and what an achievement setting this problem is by Ito Kanju), you need to see some of the other stuff behind the lines we were forced to reject. >From my point of view, the problem started when Steve told me he had been looking at it, but could not find the finishing mate. The first 12 moves were the analysis Steve sent to me (I couldn't see my way clearly at first, and I am naturally inclined not to spend very long on a problem if I can't see how to start it - this problem is in contrast with D84, where I saw the first move instantly (before looking at Steve's computer-generated solution), and after that, it would merely have been a question of sitting down for about an hour, and working through the lines. So you may ask why I hadn't done so before - the answer is simply that George's description of the problems made me think that they were all insoluble (D84 is really quite easy, I don't understand how it can have been unsolved for so long, unless everyone else takes the same attitude as me) along with some of his comments: This is the (a?) sequence of moves that forces the King to the left hand side of the board where common-sense dictates that there is a mate involving the promotion of the Lance and Silver. 1. +RC-2j, +Gx2j; 2. S-2l, Kx2l (if K-1i 3. S-1k mate.); 3. Kyx2j, K-3l; 4. R-3k, K-4l; 5. +RC-6j, +RCx6j (if K-5l see below for mating sequence) 6. Ky-4j, K-5l; 7. R-5k, K-6l; 8. Kyx6j, K-7l; 9. R-7k, K-8l; 10. Ky-8j, K-9l; 11. Rx9k, K-10l; 12. Kyx10j, K-11l Move 5 is rather neat and is not at all obvious (but the progression is doomed without it). ...after this I get stuck. My first reply, and attempt at a solution was: What Lance? Oh! - That Lion is a Lance! (An aside: it is all too easy to mis-read Forsyth notation. Having set the problem up, I always check it again, but this time I failed to notice that the l stands for Lance and not Lion. So I was looking at this position, and wondering what was wrong with Lnx12i-11j mate. I'm know I'm not the only one to suffer from this sort of thing with Chu mating problems. If you have supplement no. 3 handy, look the errata for page 90. I spotted the error, and reported it to George. He came back with another solution, but it was in error - he had set the board up wrongly (probably after exploring one line and back-tracking. Finally he found the solution in supplement no. 3. George's comment: "Oh well, you know how it is." I do indeed - it keeps happening. Common sense says to look at what the promoted Bishop can do, also. 13. R - 11k, K - 12l 14. Ky - 12j, R x 12j 15. R - 11d+, R - 10j (or K - 12k, +B - 11k+) 16. +B x 10j, K - 12k 17. +B - 11k mate Steve pointed out that on move 14 (did you see it, or was it the computer?), the Rook can promote when it captures (we have been discussing whether it is legitimate for a piece to promote when it is already in the promotion zone. My suggestion was that if the piece could be proved to have moved already after entering the promotion zone (such as the Phoenix in D84), then it was allowed to promote, but otherwise not. But in this case, the promotion is certainly allowed, as it was a capture. At this point, Steve gave up with D29 (subject to verification by George that the set-up was correct). I pointed out that the Rook could easily be a promoted Gold (have a look at the Kanji on the back of MSM, and you'll see what I mean). (what I didn't say, was that I thought this would be a rather disappointing (relatively speaking, the progression of the first 12 moves is a good problem in it's own right, I think) problem, if the only purpose of the Lance and Silver was to mislead the poor innocent problem solver into going down the wrong path.) But then I looked again. if Ky - 12j doesn't work, then Ky - 11k, Ky - 10l or +B - 1b (a move earlier) must be the right move. I quickly rejected Ky - 10l (as +SM x 10l seems to give White too much defence). Ky - 11k, K - 12k, and nothing seems to work. So I concentrated on B - 1b. Well, I played around with that for some time, but I was forced to drive the King out across the tenth file, and had to give it up. Time to go for a walk. It doesn't make sense! S - 11d+ to make use of the Lance simply MUST be the theme of this problem. Steve had previously said: I'm convinced that the sequence of moves through to 12 or 13 are correct but after that I just can't work it out. My only thought is that there may be some way to bring the +B on 1a into the action earlier on. This piece seems to be slightly out of position for the final few moves. I'll have another look at Ky - 10l, and see if I can't do something with bringing the promoted Bishop in. Then after a few moments, I was ecstatic - this was it! So I composed an email to Steve, confident I had got a wonderful solution. But as I wrote it out, I became aware that the mate depended upon Black taking advantage of an interpretation of the repetition rule that I made up on the spot (that the DEFENDER must vary). This was disappointing. Although there was clearly some historical confusion about the repetition rule (see Wayne Schmittberger in MSM), I had never heard of a suggestion that the defender might have to vary. Still, it is an interesting theme, so I suppose it might be legitimate for a composer to use it in a problem (but then, surely he would have said so (unless it was the accepted rule in problems at that time ??), and then surely we wouldn't have lost that, but retained the rest of the problem. In addition, there was the fact that the Rook didn't have to promote - it could move to any square short of the FL, and there still wasn't a mate (in particular, as I now realise, having seen Steve's solution, it could move to 11i, thus enabling the promoted Bishop to cross the i rank without the need for the Lance, but this theme of needing the Lance to cross the i rank with the promoted Bishop is still important, because there is no mate on 11j unless the Rook is promoted, but with the Flying Stag on the board, this mate doesn't happen). I show it as promoting, because then the role of the Flying Stag becomes clear (it doesn't show up at all in the true solution, which is a strong reason for showing this line - otherwise you might think there was a superfluous piece - there is not - this is a superb problem). Anyway, here are the moves: 13. S - 11d+, FL x 11d (or K - 12l, Ky - 12j mate) 14. R - 11k, K - 12l 15. Ky - 10l, +SM x 10l 16. R x 11d+, K - 12k (here, and throughout the rest of the problem, if +SM - 11k, +B x 11k mate) 17. +B - 2a, K - 12l (here, and throughout the rest of the problem, if K - 12j, then +B - 11j mate) 18. +B - 2b, K - 12k 19. +B - 3b, K - 12l 20. +B - 3c, K - 12k 21. +B - 4c, K - 12l 22. +B - 4d, K - 12k 23. +B - 5d, K - 12l 24. +B - 5e, K - 12k 25. +B - 6e, K - 12l 26. +B - 6f, K - 12k 27. +B - 7f, K - 12l 28. +B - 7g, K - 12k 29. +B - 8g, K - 12l 30. +B - 8h, K - 12k 31. +B - 9h, K - 12l 32. +B - 9i, K - 12k (here, and throughout the rest of the problem, if R x +B, L - 12d+, and mate (after the Rook and Free Boar interpose)) 33. +B - 10i, K - 12l 34. +B - 10j, K - 12k 35. +B - 11j, K - 12l (if K - 11l, then +B - 10j, and as K - 12k would then break the repetition rule (by order of move repetition), White must play +SM - 11k, +B x 11k mate) 36. +B - 10j, +SM - 11l (to avoid repetition by order of moves) 37. +B x 11l mate I submitted this to Steve as a Solution (and posted to SHOGI-L at the same time, to sound out opinion on the likelihood of the reptetion rule), but I was wondering if the computer might not find a better mate from around the position of move 32 (Steve's comment here shows the limitation of the computer in long problems: I'll look at this when I can and get back to you. Last night I tried this slow advance of the +B hoping that there might have been something beyond the horizon effect of the program but didn't get anywhere. As I have already said the Zillions engine has some difficulty with repetition, where it applies the chess rules whether you want it to or not. I can't help feeling a little uncomfortable about move 36.) Still, I'm certainly happy after seeing this to thrash it around some more. I too was uncomfortable about move 36. But maybe Steve or his computer program would come up with something. 13. S-11d+, FLx11d (or K-12l, Ky-12j mate) 14. R-11k, K-12l 15. Ky-10l, +SMx10l 16. R-11i, K-12k (here, and throughout the rest of the problem, if +SM - 11k then +B x 11k mate) 17. +B-2a, K-12l (here, and throughout the rest of the problem, if K - 12j then +B - 11j mate) 18. +B-2b, K-12k 19. +B-3b, K-12l 20. +B-3c, K-12k 21. +B-4c, K-12l 22. +B-4d, K-12k 23. +B-5d, K-12l 24. +B-5e, K-12k 25. +B-6e, K-12l 26. +B-6f, K-12k 27. +B-7f, K-12l 28. +B-7g, K-12k 29. +B-8g, K-12l 30. +B-8h, K-12k 31. +B-9h, K-12l 32. +B-9i, K-12k 33. +B-10i, K-12l 34. +B-10j, K-12k 35. Rx12i, +SM-12j (or K-11l, 36. R-11i, K-12l (or +SM-11k, +Bx11k mate) 37. L-12d+ mate) 36. Rx12j, Kx12j 37. L-12d+, FL-12e 38. +Lx12e mate. The alternative (switch-back) line from 5... is 5. .... K-5l; 6. R-5k, K-4l; 7. Ky-4j, K-3l; 8. R-3k, K-2l; 9. Ky-2j mate. Steve> This really is a brilliant problem, and worthy of the great Steve> Ito Kanju (if it is his). 38 moves! C49, eat your heart out. What's a mere 22 moves (OK, so there are 12 lines of this length, but ...)? Hm. Probably only counts as a 37 move mate - the block by the FL makes no difference, and is therefore conventionally ignored (which is why I have only counted to 37 moves on the variation I inserted at the end - the two variations are the same length). Still, beats 22 moves hollow! The role of humans co-operating is clearly shown here (I wouldn't have started it if Steve hadn't done the first bit, and Steve would have given up if I hadn't persisted). As for the machines, we must not forget that all the communications between Steve and myself (which were vital - I would never have kept this up if we had relied on snail-mail). And then there is Steve's computer program (and the people who developed Zillions of Games), which had some role in this I think (Steve - please enlighten us). -- Colin Paul Adams Preston Lancashire