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Cylindrical Chess. Sides of the board are supposed to be connected. (8x8, Cells: 64) [All Comments] [Add Comment or Rating]
HaruN Y wrote on Mon, May 6 06:32 AM UTC:Excellent ★★★★★

K+2B can only draw.


Michael Nelson wrote on Tue, Mar 21, 2023 01:45 PM UTC:Good ★★★★

Very nice touchup of the page. You might have mentioned that in problems, there is more than one way to use the cylinder concept. The one here described is chess on a horizontal cylinder, which is the only form that is playable as a game. Other forms have appeared in problems: the vertical cylinder with the first and last ranks connected and the anchor ring both basically both a vertical and horizontal cylinder simultaneously. In the latter case, a1 is connected to both a8 and h1 (and in some version h8 as well, if you really want to go crazy). With rooks and queens instantly attacking each other and the kings in mutual check, we'd need special rules to play this, but a KBB vs K ending on such a board can be analyzed, as well as more complex problems.


🕸Fergus Duniho wrote on Wed, Mar 1, 2023 02:25 AM UTC:

As one last touch-up before featuring this game, I replaced the diagrams with ones that have better-looking piece images.


H. G. Muller wrote on Tue, Feb 21, 2023 01:45 PM UTC in reply to Fergus Duniho from 01:12 PM:

It could have been your own remark. It was on the page with the diagram. It was removed after you modified how the diagram works.

Yes, that was my remark. After inserting the Interactive Diagram I noticed that the move diagrams were never showing a move that crossed the border, and since it struck me as an unacceptable flaw to invite people to summon up useless move diagrams (as the text above it did), I added this as a warning. I had not foreseen the usual optimum of putting the piece in the center would backfire here.

In my philosopy, when you invite people to activate a certain feature, they should be able to rely on it that this will actually work satisfactorily. This is why I considered it a bit silly to accompany it with a message basically saying "hey, see that list with pieces on which you can click to demonstrate their moves? You'll never guess, but if you click those, you will actually be demonstrated to you in a useful way!".


🕸Fergus Duniho wrote on Tue, Feb 21, 2023 01:12 PM UTC in reply to H. G. Muller from 08:17 AM:

I don't see any such remark from Greg, neither in the article, nor in the comments. Are you sure you are not attributing my own remark (which I added together with the Diagram, and deleted now that the problem is fixed) to Greg?

It could have been your own remark. It was on the page with the diagram. It was removed after you modified how the diagram works.


H. G. Muller wrote on Tue, Feb 21, 2023 08:17 AM UTC in reply to Fergus Duniho from 12:03 AM:

Before you introduced the feature of placing pieces in other positions than the center, Greg, the very author of this page, noted that the interactive diagram wouldn't be very helpful for showing how the pieces moved differently than they do in Chess. So, far from being a far-fetched assumption, it is one that a qualified person already made.

I don't see any such remark from Greg, neither in the article, nor in the comments. Are you sure you are not attributing my own remark (which I added together with the Diagram, and deleted now that the problem is fixed) to Greg?


🕸Fergus Duniho wrote on Tue, Feb 21, 2023 12:03 AM UTC in reply to H. G. Muller from Mon Feb 20 02:23 PM:

It is really a very far-fetched assumption that people would beforehand come to the conclusion that the move diagrams must be no good without even trying, no matter whether they are intimately familiar with the Diagram or not.

Before you introduced the feature of placing pieces in other positions than the center, Greg, the very author of this page, noted that the interactive diagram wouldn't be very helpful for showing how the pieces moved differently than they do in Chess. So, far from being a far-fetched assumption, it is one that a qualified person already made.


H. G. Muller wrote on Mon, Feb 20, 2023 02:23 PM UTC in reply to Fergus Duniho from 12:44 PM:

Well, not really. Next to the Diagram there is a list of the pieces and squares where they start, (as is usual in Setup sections), and the header of that list is in permanent view, and says "Click below to display piece moves:". So they don't have to open anything. They just have to do as instructed.

And they should be able to count on it that such instructions do not mislead them into performing useless actions. If the move diagrams were no good I should (and would) have omitted this list (which is an optional 'satellite' embedded in the text) from the Diagram. Or, as I did when the Diagram was only in a comment, before implementation of the new feature, accompany it by a warning that the move diagrams are no good. It is really a very far-fetched assumption that people would beforehand come to the conclusion that the move diagrams must be no good without even trying, no matter whether they are intimately familiar with the Diagram or not. It even surprised me.


🕸Fergus Duniho wrote on Mon, Feb 20, 2023 12:44 PM UTC in reply to H. G. Muller from 08:26 AM:

I was putting into words what people will not see with their own eyes unless they open up the interactive diagram and click on something that let's them see more diagrams. Not everyone is as familiar with interactive diagrams as their creator is, and what is obvious to you will not be obvious to many people. Additionally, repositioning the piece in the diagram is a new feature, and people who are already familiar with how interactive diagrams have worked in the past might not expect to see useful diagrams for this game unless they are notified of this change.


H. G. Muller wrote on Mon, Feb 20, 2023 08:26 AM UTC in reply to Fergus Duniho from Sun Feb 19 08:47 PM:

Well, explaining to people in words what they already can see with their own eyes seems a bit patronizing and redundant to me. Every Interactive Diagram can be used to see how pieces move differently from in orthodox Chess. This Diagram is not any different in that respect. It is just that the optimal placement of pieces to show their moves needs not be the same for every type of move, even though for the large majority central placement is best. It can be expected from the creator of such move diagrams that he made his best effort to provide a good one, in that respect. Why elaborate on the obvious?


🕸Fergus Duniho wrote on Sun, Feb 19, 2023 08:47 PM UTC in reply to H. G. Muller from 05:22 PM:

I have put that back now, and also surrounded the paragraph that encourages readers to turn on JavaScript on within <noscript> tags.

I intentionally did not use <noscript> tags, because by default, the NoScript extension will disable them. Also, the text provided an introduction to the Interactive Diagram and how it differs from the usual Interactive Diagram, which is relevant information even if JavaScript is working. So, I have removed them.


H. G. Muller wrote on Sun, Feb 19, 2023 05:22 PM UTC in reply to Fergus Duniho from 03:58 PM:

Beware that you should preserve the display:none style and the HTML id, when you do a thing like that, in order to prevent the Diagram definition to be displayed as text when JavaScript is disabled. I have put that back now, and also surrounded the paragraph that encourages readers to turn on JavaScript on within <noscript> tags.


🕸Fergus Duniho wrote on Sun, Feb 19, 2023 03:58 PM UTC in reply to H. G. Muller from 09:25 AM:

Problem is that for those who have JavaScript switched off this section would be empty.

This is easily addressed by adding more content to this section, as I have now done.

I tried to cure that by putting <div> tags around the header and Diagram (= <table>) together, and unhide that through JavaScript rather than just the <table>, so they would both fail to appear when JavaScript is disabled.

I have now removed this.


H. G. Muller wrote on Sun, Feb 19, 2023 09:25 AM UTC in reply to Fergus Duniho from 02:41 AM:

I added an H2 "Interactive Diagram" heading, ...

Problem is that for those who have JavaScript switched off this section would be empty. I tried to cure that by putting <div> tags around the header and Diagram (= <table>) together, and unhide that through JavaScript rather than just the <table>, so they would both fail to appear when JavaScript is disabled.

This, however, appears to make FireFox forget how a <H2> header should look on this page. I guess this could be cured by explicitly repating the required style in a style property of the <H2> element. What style properties are used in our articles?

For uniformity with other articles I changed the header to 'Setup'; the Diagram itself already announces that it is interactive, just below the header. Other articles have the Interactive Diagram in their Setup section. But 'modest variants' usually don't have such a section.

I also enhanced the Diagram script to make the board location where the piece will be shown in move diagrams configurable. By default it would use the board center for this. Which is usually what one wants, as this leaves the most room for distant moves on all sides. For Cylinder Chess this prevented the move diagrams to show any moves that crossed the edge, though, making them indistinguishable from the FIDE counterparts, and thus pretty useless. I made use of the new midX and midY parameters to make the pieces appear on the left edge in move diagrams.

This doesn't really provide an unambiguous indication of castling, as the a-side castling is now not shown (as it crosses the edge). Since the article spends ample text on explanation of the castling rule this doesn't seem a real problem, however.

Another case where an alternate positioning in the move diagrams was desirable was Scheherazade: many leapers there are so long range that even on a 10x10 board they don't have any moves at all! So in the Diagram I posted as a comment a page earlier I now make the pieces appear near a corner.

BTW, the case of a Rook blocked on a rank and still being able to use the other side of the obstacle by wrapping is covered by the Interactive Diagram, when tou place the obstacle by hovering in the path of the Rook in its move diagram. The move diagrams do support (single) blocking of sliders and activation of hoppers that way.


🕸Fergus Duniho wrote on Sun, Feb 19, 2023 02:48 AM UTC:

I think it would be helpful to include a diagram of a Rook, showing it blocked from the edge on one side but still able to reach that edge by moving in the opposite direction.


🕸Fergus Duniho wrote on Sun, Feb 19, 2023 02:41 AM UTC:

I made a couple cosmetic changes to this page. I added an H2 "Interactive Diagram" heading, and I floated the photo to the right so that the introduction takes up less space on a desktop monitor. To do this, I moved the photo in front of the text. So, on a small enough mobile device, it should show up above the text.


📝Greg Strong wrote on Mon, May 27, 2019 12:48 AM UTC:

I have added a few more things to this page that I found in Variant Chess magazine, issues 22 and 48.  There is more information about the history, a note that the Bishop attacks the (4, 4) space by two different paths allowing it to issue double check by itself, and more information about endgames.  I was thinking that a Bishop pair probably won't be able to mate but that is not correct.  In fact, even if the orther side has a Knight, according to Variant Chess issue 48, the Bishop pair will still mate in at most 18 motes.  I have not verified that move count, but I have verified that KBB forces mate against KN. The outcome of KBN vs. K is still unknown.


📝Greg Strong wrote on Sun, May 26, 2019 01:59 AM UTC:Excellent ★★★★★

The page for this game was very old and the content wasn't really appropriate as a formal description of this historic game, so I have completely rewritten it.  The original version can still be found here.


📝Greg Strong wrote on Fri, May 24, 2019 11:44 PM UTC:

I have now added support for this to ChessV 2.  Silly me, I thought this would be pretty simple.  All directional movement is handled by lookup from a big multi-dimensional array indexed by direction number and square number that gives the number of the next square in that direction or -1 if it leads off-board.  I thought I could just update that lookup table to accomodate the board wrap and I'd be set.  But, of course, there were several additional challenges:

First, I had infinite loop problems since a Rook on an open rank can just zoom around and around.  Needed to add a check to internal move generator to stop generating whenever a piece returns to its starting square.  (And not generate that move, since null move is not allowed.)  This check will slow down, at least microscopically, move generation in all games, most of which don't have this problem, but that's life.  ChessV is not built for efficiency.  And Circular Chess is another example of a game with this problem.

Next, I had an issue with the move generator generating duplicate moves.  If a Rook is on a rank that is empty except for one enemy piece, that piece can be captured by two different paths.  So the generator adds the capture twice.  This is not good.  So I had to build deduplication capability into the move generator.  This is slightly expensive, so it is controlled by a Game flag and only enabled for games that need it.  (This could be an issue for more than games with funky boards - for example Switching Chess - a1 switches with b1 is really no different than b1 switching with a1.)

Then, a related problem with having multiple paths between squares, is that this could totally screw up the Static Exchange Evaluator (SEE).  A fix for that would be complex and I wouldn't want to complicate the regular SEE engine so it would require building a special one just for this game. And I'm not doing that.  So I switch it off.  There was already a game flag for disabling SEE since other games I've implemented are not compatible - most notably, anything with a Chinese Chess Cannon (or similar piece.)  I've tried to think about how SEE should be reprogrammed to support cannon-type pieces, and it is a fascinating problem, but it makes my head hurt.  Quite frankly, I don't think I'm smart enough to ever get that right.  Fortunately, SEE is a nice trick but not really necessary.  Quiescent search solves the same problem, and more accurately, just far more slowly ...

Ok, at this point, we have a functioning, accurate program.  But there are still problems with the positional evaluation functions.

Piece-Square-Tables (PST) encourage pieces to move into the center, but this game has a radically different concept of "center."  Instead of a square, the center is a stripe accross the center of the board.  Fortunately, I could adjust which squares were considered part of "small center" and "large center" and that fixed the PSTs intelligently.  It also fixed the consideration of which squares are elligible for knight outposts. This change was clean and worked out well.

Then there is pawn structure evaluation, and this is important.  There are a number of issues, for exmaple ... We penalize isolated pawns. But in this game, an A-pawn is not isolated, even if there is no B-pawn, if there is an H-pawn.  I was able to fix pawn structure issues pretty cleanly.

Then there is end-game evaluation.  King+Rook is no longer a win, it is now a draw.  So I fixed that, although in a cheesy way. (I also fixed this issue in Omega Chess while I was at it.)  But this "fix" was not good, and there are probably other changes required ... can KBB or KBN mate?  Probably not.  But that's enough for now. I expect I've already reached the point where this will be the world's strongest Cylindrical Chess engine (not that I've looked) and this is a lot more time than I had planned to invest in this.


📝Greg Strong wrote on Sat, May 18, 2019 11:20 PM UTC:

Ok, it seems King + Queen can mate.  Which is good.  If they couldn't, that would also mean that King + Pawn would be a draw.


📝Greg Strong wrote on Sat, May 18, 2019 04:01 PM UTC:

Jeffrey T. Kubach wrote on 2017-04-23 UTC:

Maybe they should make a restriction on the king - he is restricted to the usual board edges perhaps?

I was thinking the same thing.  King + Rook vs. King can't force a mate.  I'm not even sure King + Queen can force a mate.


Kevin Pacey wrote on Thu, Mar 1, 2018 07:44 AM UTC:Excellent ★★★★★

In interesting variant that has a board geometry somewhat like that of Circular Chess.


Ben Reiniger wrote on Tue, May 16, 2017 06:49 PM UTC:

A beautiful spherical board for cylindrical chess:
http://makezine.com/2017/04/13/playing-chess-on-a-globe/

(Test edit; I can't edit this using the ordinary user edit script, but can using the editor script. An error in the new Session scripts?)


JT K wrote on Sun, Apr 23, 2017 02:15 AM UTC:Good ★★★★

I've heard of non-edge variants of chess, but I hadn't read this specific page until just recently.  The game seems interesting and might eliminate the usual "going for the center in the opening" strategy.  Still, I can't help but wonder if the king might be tough to mate if there are no right and left edges.  Can a knight, bishop and king mate the lone opponent king?

Maybe they should make a restriction on the king - he is restricted to the usual board edges perhaps?


Daniil Frolov wrote on Thu, Jun 3, 2010 08:20 AM UTC:
Oh, yes, it was mistake, just like king or general may move directly away from cannon without puttting itself in check.
But such game, where position, wich was before making move is more important than position after making move, would be interesting...

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