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The Chess Variant Pages




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Amphibians synergy bonus compared to other compounds[Subject Thread] [Add Response]
Ben Reiniger wrote on 2022-11-29 UTC

From the chess StackExchange site comes this variant question: https://chess.stackexchange.com/q/41052/18278

To paraphrase very briefly: compound pieces seem to often have a synergy value of 1 (e.g. Q=R+B, v(Q)=9, v(R)+v(B)=8); do amphibians see a larger synergy bonus arising from their un-binding?


Horde chess[Subject Thread] [Add Response]
H. G. Muller wrote on 2022-11-15 UTC

Why Horde chess exist on Lichess and aren't on Chessvariants?

Well, it is nearly the same as Dunsany's Chess. Perhaps it could be added as a note to that page, and the page also put in the alphabetical index under Horde?

As to why variants that are on LiChess might not have an article here, you should pose that question primarily on the LiChess forums. If no one from LiChess creates a page for it, then it is unlikely to be here. Most people here do not visit LiChess, and even when they do, not many people would create articles about someone else's chess variant.


Rechefiltr is Fire wrote on 2022-11-15 UTC

Why Horde chess exist on Lichess and aren't on Chessvariants? I tried to write Horde's rules but I met a page's number limit) Please write. Lichess is free chess site with billions of games and millions of players worldwide♡


Possible problem in PGP code [Subject Thread] [Add Response]
wdtr2 wrote on 2022-11-05 UTC

yes, PHP. lol. oops. Thank you.


Fergus Duniho wrote on 2022-11-03 UTC

I don't know what PGP has to do with Game Courier, but the problem is now fixed. Perhaps you meant PHP.


Stockfish and chess variants [Subject Thread] [Add Response]
Aurelian Florea wrote on 2022-11-03 UTC

Thanks, HG!


H. G. Muller wrote on 2022-11-03 UTC

This is what I expected. Stockfish uses bitboards, and the standard algortithms for bitboards are very much specialized for sliding along diagonals and orthogonals. Fast algorithms for check detection also often assume that moves are reversible which is also not true for bent riders.


Aurelian Florea wrote on 2022-11-03 UTC

So it seems stockfish cannot do bent riders!


Daphne Snowmoon wrote on 2022-11-02 UTC

https://github.com/ianfab/Fairy-Stockfish/blob/master/src/variants.ini

It might be good to take a look at this. Variants created by individuals are implemented by this definition.

And I use Fairy Stockfish via WinBoard (XBoard), I'll give you the file if you need it.


Aurelian Florea wrote on 2022-11-02 UTC

Thanks, Daphne! Have you any idea about what fairy pieces it recognizes?


Daphne Snowmoon wrote on 2022-11-02 UTC

Aurelian Florea //

https://github.com/ianfab/Fairy-Stockfish/releases/tag/fairy_sf_14

I downloaded Fairy Stockfish from assets here.

https://discord.gg/aPs8RKr

It might be quicker to ask on this channel how to use Fairy Stockfish.


Aurelian Florea wrote on 2022-11-02 UTC

I have seen below a discussion involving stockfish and chess variants. I did not knew that there is a connection. Can someone explain me please what variants, stockfish can play!


Possible problem in PGP code [Subject Thread] [Add Response]
wdtr2 wrote on 2022-10-27 UTC

Using Self play against the game https://www.chessvariants.com/play/pbm/play.php?game=Pocket+Shogi+Copper&settings=default

Now move the black bishop to the center of the board without a capture (when that move is legal). (3rd or 4th move)

I think This move will produce a "move" parse error IMO.

There has been no coding changes to that game for many years.


Did something change in the Code syntax?[Subject Thread] [Add Response]
Fergus Duniho wrote on 2022-10-26 UTC

Please provide a link to the code that isn't working.


wdtr2 wrote on 2022-10-23 UTC

A few months ago (perhaps a year or more), the code for shogi was modified. We now seem to have special variables like pawn-range etc.

The code I copied and modified many years ago does not seem to be working. Below is an error message below that I got using my old code where b is a black bishop, when I attempt to do a drop I seem to get the error message The move MOVE: b*9h ain't well-formed.

Any suggestions on how I should correct this?

Array ( [0] => MOVE: [1] => b [2] => * [3] => 9h )

ILLEGAL: b*9h on turn 8:

The move MOVE: b9h ain't well-formed. b is a coordinate. So should be a hyphen.

Go back with your browser's BACK button, reload the page, and try again.

For diagnostic purposes, here is the full movelist:

  1. p 8g-8f 1... P 8c-8d
  2. n 9i-8g 2... N 9a-8c
  3. n 8g-7e 3... N 8c-9e
  4. n 7e-8c; +n-dest 4... N 9e-8g; +N-dest
  5. +n 8c-9b 5... +N 8g-9h // - bCapture- -
  6. s 8i-9h 6... B*8g // - Check! -
  7. s 9h-8g 7... P 4c-4d
  8. b*9h

Setup graphics, piece sets[Subject Thread] [Add Response]
H. G. Muller wrote on 2022-10-20 UTC

The obvious remaining reason to favour static images over the interactive diagram is that the latter only works with Javascript enabled. I suppose the obvious(?) way around that would be to also have the design wizard generate a link to a Diagram‐Designer‐ or Scalable‐Diagram‐Editor‐generated (if the latter gets installed?) image and wrap it in <noscript> tags?

Indeed, this is what I have done in my own articles that use Interactive Diagrams as principal diagram. I don't think a special application would be needed to generate the static image; once people would have created an Interactive Diagram to their satisfaction, they can simply take a screenshot of it to obtain an identical static image, and upload that.

But there are two different issues here: (1) how we could streamline the submission process, and guide the user to submit articles in a form we like to have them, and (2) what we would like best, and whether we should make an effort to give the CVP website a facelift to cast existing articles authored by people that have left long ago in that form.

For the moment I would like to focus on (2). If we all agree that the Interactive Diagram at its current stage should be preferably used as principal image of the initial setup, I am in favor of starting working towards that goal, and replace the images there are now by Interactive Diagrams (with 'noscript' static backups). We can argue about how perfect the Diagram representation has to be in order to be superior to a static image. (E.g. should the AI work perfectly, work at all, or would it be sufficient to just use it for summoning move diagrams and highlighting piece moves?) Or how poor the image that there is now should be in order for replacement by anything whatsoever to be an improvement.

I would for instance be in favor of replacing all ASCII diagrams, even for games the Diagram cannot actually play (yet?), and even when some of the more quirky rules (such as turning a piece of choice into a King when you lost your old one) can not be implemented when the Diagram is operated by the user. Even a static screenshot of the Diagram would be an improvement there.

I have already started churning out Diagrams for all variants in the Alphabetical Index that are playable, and can be made to look like the static image the article is using now (if not ASCII). I think I worked my way all through 'a' now. A problem is that the CVP seem completely unorganized as to available piece graphics; some of the diagrams use piece images that are probably available, but I have no idea where to find those.


Borderline[Subject Thread] [Add Response]
Gerd Degens wrote on 2022-10-18 UTC

I would like to introduce a new variant - called 'Borderline'.

It is a minimalistic version on a 7x7 board, without pawns, with only one king to capture, no capturing of opponent pieces. Rank 4 is the borderline, which must be crossed to attack the king. The pieces move according to FIDE rules.

Perhaps the variant is a bit too minimalistic, but it seems pleasantly playable.

I don't know if such a variant has been presented before. But I'm sure the community knows it.


Metamachy preset not working[Subject Thread] [Add Response]
Jean-Louis Cazaux wrote on 2022-10-15 UTC

I get the same. Maybe something is wrong in the setting of the invitation


Aurelian Florea wrote on 2022-10-15 UTC

I'm trying to accept a metamachy challenge but I am getting the following error:

"Your userid is catugo. This log is private. It may be viewed only by the players. If you are one of the players, please sign in first. You may use the menu for this."


Setup graphics, piece sets[Subject Thread] [Add Response]
H. G. Muller wrote on 2022-10-12 UTC

The Interactive Diagram can now also generate the list of pieces and their starting square as lines of text, rather than as a table (like it was doing in the original posting of this Diagram). Whether one or the other method is chosen depends on how you embed the piece list on the page. In both cases the HTML tag pair that indicates the point where the list will be inserted will have to have id="pieceList". When the tag having this id is an unnumbered list (<ul>), the Diagram script will fill it with clickable list items for the pieces. When it is a paragraph (<p>) it will create text lines from clickable spans to describe the initial piece set up, like in the example below.

I am not sure whether the blue text for reminding people that the text can be clicked is optimally placed; there seems enough room to put it behind the 'White:' header on the same line.

graphicsDir=/graphics.dir/alfaeriePNG/ whitePrefix=w blackPrefix=b graphicsType=png squareSize=50 darkShade=#3030FF rimColor=#C0C0FF promoChoice=ACIWBRNF symmetry=none firstRank=1 useMarkers=1 satellite=nutters royal=11 royal=10 pawn::::a2-h2,,a7-h7 waffle::WA:elephantwazir:b1,g1 fad::FAD:elephantferzwarmachine:c1,f1 bede::BD:bishopwarmachine:a1,h1 cardinal:A:BN::d1 fibnif:I:FvN:narrowknightferz:,,b8,g8 charging knight:N:fhNbsWbF:forwardknightbackwardsprince:,,c8,f8 charging rook:R:fsRbWbF:forwardrookbackwardsprince:,,a8,h8 colonel::fsRfhNbWF:forwardchancellorprince:,,d8 clobber king:K:KirO2ilO3:king:e1 nutty king:K:KisO2:king:,,e8

Note that the starting squares of black pieces are now also mentioned. This is another improvement; only the white pieces used to have their starting squares mentioned. Because those are the only coordinates the user must supply when specifying the Diagram. For the black pieces one usually depends on the symmetry setting (mirror or rotate) to deduce the black starting squares from the white. The Diagram now converts the deduced starting squares to text form so that it can give them for the black pieces even in those cases (and for asymmetric setups displays those as given by the user).


H. G. Muller wrote on 2022-10-10 UTC

Well, as a compromise I introduced a parameter fileOffset (default value 0), which determines how much the normal file labeling is shifted to the right (white POV). Where the alphabet is treated as a cyclic set a-w. This means that for fileOffset=1 the left edge gets labeled 'w', and the right edge just gets the next character in the normal sequence (so 'i' for Brouhaha. This was easy to do, and offers at least some improvement for the rare case one would want this.

This would not allow pasting of Game-Courier notation into the Diagram for Brouhaha (assuming the preset there uses the labels x and y), as GC always mentions the square of origin, and the Diagram would not recognize those labels. But I guess GC notation would not be accepted anyway, as it has a space between piece ID and the coordinate move. (This could probably be solved by making the parser ignore all strings of length 1, though, as the piece ID is redundant.) But relatively simple pre-processing of a GC game with a text editor (globally replacing 'y' -> 'i' and ' x' -> ' w') could solve that.

For Omega Chess the wizard squares would become w0, w11, k0 and k11. As the Wizards starting there are also color bound these are not very likely to appear in game notation, unless you would actually move something to those.


Comment Searching is Working Again[Subject Thread] [Add Response]
Fergus Duniho wrote on 2022-10-10 UTC

Since we're using MariaDB 10 again, I relearned how to enable fulltext searching and added a fulltext index to the appropriate column in the Comment table. So, we can now search the comments again.


Setup graphics, piece sets[Subject Thread] [Add Response]
Greg Strong wrote on 2022-10-10 UTC

I'm not really concerned about backwards compatibility, but on further consideration it is probably not worth modifying the program for this. It would make the program more complicated for very little gain. It is a very unusual use case, and there will always be some games that its not going to accommodate (Alice Chess, Backlash, Viking Chess, Marseillais, etc.) And since you mention Omega, yes, it has even stranger square naming. The four extra "Wizard squares" are annotated w1, w2, w3, and w4.


What's New?[Subject Thread] [Add Response]
Ben Reiniger wrote on 2022-10-09 UTC

I've added a link to What's New to the menu. It already appears on the home page under the Explore heading.


Setup graphics, piece sets[Subject Thread] [Add Response]
Ben Reiniger wrote on 2022-10-09 UTC

(I think I've fixed the subject title for comments in this thread; it wasn't an artifact of the site move, but rather of me not being thorough enough in database edits when I moved over the two first comments.)


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