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This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2005-04-22
 Author: Hans L. Bodlaender and Antoine  Fourrière. Marseillais Chess. Move twice per turn. (8x8, Cells: 64) (Recognized!)[All Comments] [Add Comment or Rating]
wdtr2 wrote on 2019-11-13 UTC

Tough Question.  I could see the 2nd move being "pass", and if Marseillas is a mandatory 2 move game per person, it is a strong arguement that it is a stalemate.  You are the programmer to the game, I would pick the one Fergus Likes, and make sure it is mentioned in the rules.


Fergus Duniho wrote on 2019-11-12 UTC

One more issue has come up. Suppose that a player makes a first move that leaves him with no legal second move. Does this end his turn like a checking move would, or does it end the game in a draw? Pritchard says in Popular Chess Variants, "A player who is not in check and cannot complete his turn is stalemated." This suggests the latter, but he could have said it more explicitly if that is what he meant. Is there any consensus on how being unable to move on the second move should be handled?


Fergus Duniho wrote on 2019-11-12 UTC

What I cannot imagine is that the original inventor would have thought it reasonable to allow e.p. capture

  1. when the capturing Pawn has not seen the other one move past it
  2. when the Pawn that moved is no longer there
  3. when the e.p. square gets occupied

That's all reasonable, and what I've coded for Game Courier is in conformity with it. The first one is already handled by the rule that en passant is not allowed on the second move unless the player is making two en passant captures. This prevents a player from using his first move to move a Pawn into position to do an en passant capture. (Note that a Pawn that was already in the position to do this could just capture the double-moved Pawn normally and then use its second move to go to the space the now captured Pawn had passed over, reaching the same position without using en passant.)

The second is handled by setting the ep1 variable to false whenever a player moves the same Pawn again. Since ep1 would store the position of the previously moved Pawn if the last move were a Pawn move, it checks whether the second move is from that location.

The third is handled by checking for a normal capture before checking for other types of Pawn moves. If the move is a normal capture, it never gets to the code for en passant. If it's not a normal Pawn capture, then the move was to an empty space. By the time it reaches the elseif clause for en passant, it has already been determined that the space is empty.

 


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2019-05-23
 By H. G.  Muller. FairyGen. Generator for end-game tables with fairy pieces.[All Comments] [Add Comment or Rating]
H. G. Muller wrote on 2019-11-12 UTC

This unfortunately runs into one of the limitations of FairyGen: it assumes there are always at least two white pieces. It uses that for the application of symmetry to save memory: it only tabulates positions with the first piece in the triangle a1-d1-d4, and when it is on the diagonal a1-d4, with the second piece in a1-h1-h8. Other positions are mapped onto these by vertical, horizontal and diagonal flipping. But this is only done after white moves. The assumption was that a bare royal would never be able to win. Of course for 3-men EGT memory is not a very large concern, and even for 5-men the EGT would only measure 1GB (=64^5), which isn't much for today's memory technology. When I wrote FairyGen even my largest computer had only 1GB. I guess I could compile a version that doesn't apply any symetry at all, and try if that one does 1+2-men without problems. (I already have versions that I made for private use, that can handle reduced symmetry, like needed for the pieces of the CwDA Nutters army, but even there it still does horizontal flipping.)

To define divergent moves in the piecedef.ini file you can add an 'm' or a 'c' to the third parameter. E.g.

X: 1,0,sm* 1,1,sc*

would be a piece that moves like a Rook but captures like a Bishop. To define a piece that doesn't capture at all you just make all its moves 'move-only'. If you want a piece without any moves or captures, perhaps you can just leave the entire line after the colon empty. I never tried that, but I think it should work.


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2005-04-22
 Author: Hans L. Bodlaender and Antoine  Fourrière. Marseillais Chess. Move twice per turn. (8x8, Cells: 64) (Recognized!)[All Comments] [Add Comment or Rating]
Fergus Duniho wrote on 2019-11-12 UTC

So if the player moved a pawn two spaces and the placed a piece on the square passed over you would allow capture of both with a single move? 

The way it is coded, that would not happen. The first thing it checks for is an ordinary diagonal capture. If the move involves one, that's what it does, and it doesn't get around to checking for an en passant move.

I have started to look at the thread you provided a link to, and I will continue to look at it tomorrow.


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2019-05-23
 By H. G.  Muller. FairyGen. Generator for end-game tables with fairy pieces.[All Comments] [Add Comment or Rating]
Prussia General wrote on 2019-11-12 UTCExcellent ★★★★★

Very handy tool! I was able to check the end games of most of my variants. 

I do have a question on King vs Royal Wazir + knight. How do I check the winning percentage for the King? It gives me an error when I attempt 3men K.WN, whereas WN.K is a sure 0% win.

Alternative pieces that I have questions with:

how could I define a unit that cannot capture at all?

how could I drfine a unit that cannot move at all?

thanks

Prussia

 


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2005-04-22
 Author: Hans L. Bodlaender and Antoine  Fourrière. Marseillais Chess. Move twice per turn. (8x8, Cells: 64) (Recognized!)[All Comments] [Add Comment or Rating]
H. G. Muller wrote on 2019-11-11 UTC

What I cannot imagine is that the original inventor would have thought it reasonable to allow e.p. capture

  1. when the capturing Pawn has not seen the other one move past it
  2. when the Pawn that moved is no longer there
  3. when the e.p. square gets occupied

Greg Strong wrote on 2019-11-11 UTC

So if the player moved a pawn two spaces and the placed a piece on the square passed over you would allow capture of both with a single move?  To me, that doesn't fit comfortably with the spirit of chess.  Pritchard notes that the rule has changed over time, probably for good reason.  Similarly, Marseillais Chess is now played in 'balanced' form because it is clearly superior.  Old games do evolve and that's a good thing.

Here is the thread on Talk Chess where this was discussed.  In it I actually started iwth Fergus' view and was persuaded to adopt my current view.


Fergus Duniho wrote on 2019-11-11 UTC

The earliest source I can find is Pritchard's 1997 Encyclopedia, which is the source Hans originally used to write this page. It says "En passant is legal if the opponent moved a pawn two squares on either of his moves but the capture must be made at once. However, if the opponent made two two-square pawn moves, both pawns can be taken e.p. This last rule is credited to Alekhine by F. Palatz in an article on the subject (LEC Sep 1928)." LEC refers to L'Echiquier. Notably, Alekhine is not one of the inventors, and how the game should handle en passant might be something that the original inventors didn't think of. It is also unknown whether the game was invented by Fortis or by de Queylar. It has been attributed to each one, but its origins are murky.

Regarding one of the alternative rules, it says "The game was sometimes played with alternative rules: a check on the first move was illegal and a player could not capture e.p. if the pawn had been moved in the first part of the player's turn." It's very possible that Fortis and de Queylar invented similar games with slightly different rules that eventually got conflated together.

The rule that Greg Strong and H. G. Muller propose has the advantage of being the simplest to program. It works with code that has already been written for Chess. Of course, the original inventor of the game would not have had this in mind, since programming games was not an option when it was invented. However, the rules as initially described above can be programmed, and that's what I have done in Game Courier. The only issue with them is that they need emendation for a Pawn that moves twice on the same turn. If we keep those rules, then en passant capture should be impossible in this instance, or it should be allowed for the Pawn on its new space. I have the former programmed right now, whereas the latter would be trickier to program.


Greg Strong wrote on 2019-11-11 UTC

Yes, I should have said en passant only allowed if the two-space pawn move was on the player's most recent move (rather than second move) to account for this.  I just tested this situation and ChessV does allow en passant to get the king out of check.  It is implemented as H. G. suggests - any move clears the EP square.


H. G. Muller wrote on 2019-11-11 UTC

Well, another move should clear the e.p. rights generated by any previous move. Like it always does. E.p. rights are transient, and last only to the end of the next move. (And not to the end of the next turn!)


Fergus Duniho wrote on 2019-11-11 UTC

I changed it to allow en passant only when the Pawn's double move is a player's second move, and I confirmed that this change did not break any past game. But as I was rewriting the rules, one more thing occurred to me. Suppose a Pawn's double move done on the first move puts a King in check, thereby ending the turn without a second move. If this check could not be ended with an en passant capture, this could allow a King to be checkmated in a position that would not be checkmate in Chess, and this would violate the intention behind the game.

So, I think we have to exclude the rule that en passant is allowed only when a Pawn makes a double move on the second move of the turn. This could be replaced with the rule that en passant is allowed only when the double move was the opponent's last move, or it could be replaced with the rule that en passant is allowed only when the Pawn that made a double move didn't make another move after it. For the meantime, I'll change it back to the latter.


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 0000-00-00
 By Adam  DeWitt. Suzumu Shogi. 16x16 Shogi variant based on Tenjiku Shogi.[All Comments] [Add Comment or Rating]
Adam DeWitt wrote on 2019-11-11 UTC

I am removing the rules against perpetual check in all of my large Shogi variants (except for Shosu Shogi and Futashikana Shogi) for the sake of making these games programmable in Game Courier. This will be the last change to the rules of these games.


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2005-04-22
 Author: Hans L. Bodlaender and Antoine  Fourrière. Marseillais Chess. Move twice per turn. (8x8, Cells: 64) (Recognized!)[All Comments] [Add Comment or Rating]
H. G. Muller wrote on 2019-11-11 UTC

In any case it should be clear that you can never capture a piece after it moved away with the second move, just because it was in a location after its first move where you could capture it. It would be highly illogical if e.p. capture would be an exception to that. Whether you want a second move done with a different piece to destroy e.p. rights is a matter of choice.


Greg Strong wrote on 2019-11-11 UTC

This is tricky, and different players have used different rules.  This page states:

According to Pritchard's Popular Chess Variants, 'The en passant rule has seen change. Modern players allow it only when the Pawn advance formed the second move of a turn.'. This helps to eliminate some ambiguity discussed in the comments. (What if a player advanced a Pawn by two squares, then occupied the intermediate square with a piece?)

The situation is potentially even worse than this example.  What if a pawn made a double move and then went on to capture a piece with its second move?  Would capturing it en passant then magically bring back the piece it captured?

There was a discussion about this on the talk chess site a few years ago.  The discussion went on for quite a while and a lot of people weighed in.  I can try to dig up the thread, but the final outcome was that there is really only one interpretation of en passant makes sense and doesn't lead to problems: the en passant capture must be made with a player's first move and can only be used to capture a two-space move by the opponent's second move.  If a player makes a two-space pawn move with the first of his two moves, it is not subject to en passant.  ChessV uses this interpretation and I believe Game Courier should do the same.


Fergus Duniho wrote on 2019-11-11 UTC

While fixing a bug in the Game Courier code, I came across a situation that is not clearly covered by the rules. Suppose a Pawn makes its usual first-move double move, then it moves forward one more space on the same turn, so that it moves a total of three spaces forward. Can it be captured by en passant if the opponent has a Pawn in the usual position? On the one hand, it has made a double move, and a Pawn that makes a double move can normally be captured by en passant. On the other hand, it is no longer on the space it moved to when making its double move, and if the player had wanted to, he could have moved the Pawn forward one space, then captured the Pawn that was in a position to capture it by en passant if it had made a double move.

For now, I have written the code to forbid en passant capture in this situation. Does anyone know if there is any precedent for allowing en passant capture in this situation?


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2001-09-29
 Author: Daniel  Lindstrvm. Yalta. A three player chess variant. (Cells: 96) [All Comments] [Add Comment or Rating]
Colin Rowat wrote on 2019-11-09 UTC
  1. how does Yalta compare to other three-player chess variants?  (I'd come across it as a teen, so have a soft spot for it.  It also looks like a more direct extension of two-player chess than some others that I've seen - which I also like.)
  2. is there anyone who makes Yalta chess mats?

This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 0000-00-00
 By Adam  DeWitt. Suzumu Shogi. 16x16 Shogi variant based on Tenjiku Shogi.[All Comments] [Add Comment or Rating]
H. G. Muller wrote on 2019-11-08 UTC

The Q=9 > LH=8 was from http://tenjiku-shogi.net/tutor3.htm, which discusses the 'modern' version of the game, i.e. with full Lion power for the LH. (Which, IMO, also is the historic move.) But I admit that these values are controversial. In the ongoing game (#2188) at the PBeM server the opponent of my engine happily traded his Queen for the bot's Lion Hawk. As neither of the remaining Q/LH has engaged in battle so far, it has still remains to be seen who had the good deal there. It should also be taken into account that a Queen is promotable, and a Lion Hawk not. But the Q=9 value comes from a rule set that uses the TSA move for the Free Eagle, which is a rather insignificant promotion (no igui, just 4 extra jump moves to already accessible squares).

It is difficult to guess whether GG or VG is the strongest general in Suzumu Shogi. I think that even in Tenjiku Shogi GG is only better than VG because of the ranking. An area move is very powerful (up to 48 targets!), and could very well be worth more even than the orthogonal jump-captures over arbitrarily many pieces. Limiting it to jumping 2 pieces would obviously weaken the latter further.

As to the number of checks: it is obvious that the conventional rules for perpetual checking can make some theoretically won end-games very tedious, and in combination with a 50-move type rule possibly even draws. I am not sure that limiting this to 4 doesn't hurt the game, though, by making it too easy to draw. On such a big board it might be too easy to deliver 4 checks before a King can reach shelter. Think of a Rook versus an exposed King; normally the King would just creep up to a checking Rook, after which it cannot continue checking, and the checked side gets the opportunity to start his counter attack (say in K + Ln vs K + R). Especially with Jumping Generals it could be difficult to defend against checking, when the board population thins.

 


Adam DeWitt wrote on 2019-11-08 UTC

Actually, this was completely intentional. It is meant to compensate for stalemate being a win for the stalemating player. In Chess, if you're in a lost position, then the stalemate rule can save you. The rule against perpetual check has the same purpose.


dax00 wrote on 2019-11-08 UTC

I noticed that all your games of this sort forbid 4 consecutive checks for some reason. Is this a misunderstanding of the repetition rule of historical (and current) shogi variants, which forbids fourfold repetition of a position with check, or is this intentionally something different?


Adam DeWitt wrote on 2019-11-08 UTC

These are some very good questions. Here are my answers:

  • When I said that the moves of the Fire Demons and the range-jumping generals were unplayable, I was talking about when I was still experimenting with piece moves. This was before I had even joined the Chess Variant Pages. Back then, the range-jumping pieces could only jump a single piece, and I was still experimenting with moves for the Fire Demon. I'll be honest with you - some of them got very crazy. At one time I gave it the move whose XBetza notation was the incredibly long BsRvW5KaKaaKmabKcaibQ5cafKcafafKcafafafKcafafafafKafcabKafcafKafcafafKafcafafafKafafcabafKafafcabK

afafcafKafafcafafKafafafcabafafKafafafcabafKafafafcabKafafafcafKafafafafcabafafafKafafafafcabafafKafafafafcabafKafafafafcabK.

I know. It basically defies description.

  • I prefer the promotion rule from standard Shogi because not only is it much simpler to understand, it is also easier to program in Game Courier. By using the standard prommotion rule all I have to do is keep track of where the piece started and where the piece ended. If I would have used the Chu Shogi promotion rule, it would have made programming the Game Courier preset much more difficult, to say the least.
  • The reason the Fire Demon cannot jump is because allowing it to jump wouldn't fit well with the theme of the game being based on Tenjiku Shogi. Furthermore, this would potentially make the game of Mitsuguni Shogi (Suzumu Shogi's smaller counterpart) too fast-paced, even though there is only one Fire Demon in that game. Nonetheless, I have to admit that giving it the move you suggested, at least in Suzumu Shogi, could make for an interesting twist. Though I didn't really plan on giving the Fire Demon jumping moves, it's a good idea to think about.
  • Now that I think about it, I think you're right on this one. I'd say it's slightly more valuable than a single Great General or Vice General, and I definitely think it's more valuable than a Rook General or BIshop General.  Make no mistake though - even though it is not as powerful as it is in Tenjiku Shogi, the Fire Demon is still a force to be reckoned with. As for the values of the Lion Hawk and the Queen, sure, the Queen can slide in all directions, but the Lion Hawk has a fully-fledged Lion move, plus the move of the Bishop. Because of this, I would, in many cases, find it hard to believe that the Lion Hawk is less valuable than the Queen in Suzumu Shogi. The only reason it would be less valuable in Tenjiku Shogi would be because you are using the TSA rules (Bishop + 2 square area move, rather than Bishop + Lion).

H. G. Muller wrote on 2019-11-07 UTC

Interesting game. It begs some questions, however:

  • What made you decide the move of the Demon and Jumping Generals in Tenjiku Shogi make that game 'unplayable'?
  • Why do you prefer the standard Shogi promotion rule over the Chu Shogi rule?
  • What is the point of disallowing a jump for the double King move of the Demon? The area move it has would be able to reach the same squares through multiple paths, and they are unlikely to be all blocked. Especially since any obstructing enemy can be destroyed in the process. So in practice it would only delay development of the Demon, when the latter is still behind a solid wall of own pieces. Which you probably would not want to develop very quickly anyway, valuable as it is. So it doesn't seem worth introducing a new type of move, rather than just taking Demon = Buffalo + Lion + Area Move.
  • The value of the Demon with the move you give it would not nearly be 3 Jumping Generals. I am not even sure it is worth more than a single VG or GG (even when the latter have limited jumping power). The Lion power isn't worth that much, since most Tenjiku pieces are 'Lion proof' (i.e. have all King moves, so you cannot bring igui to bear on them as an attack). Note that some Tenjiku players value the Lion Hawk (as Bishop + full Lion) less than a Queen. BTW, the rule of thumb that a Demon is worth three Jumping Generals in Tenjiku Shogi only holds when these Generals are still able to inflict smothered mates, which can only be averted by giving a Demon back. Otherwise Demons that burn are priceless: losing one is losing the game. Conventional pieces have no defense against a Demon.

This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2003-01-16
 Author: John  Ayer and Hans L. Bodlaender. Inventor: Savio  Cagliostro. Cagliostro's Chess. Variant on 12 by 8 board with combination pieces. (12x8, Cells: 96) [All Comments] [Add Comment or Rating]
Kevin Pacey wrote on 2019-11-01 UTC

Does anyone know if this variant has been tested much over-the-board or online? Superficially, it looks like if a player castled (especially kingside, with the enemy queen beaming in to the l-pawn's home square right from the setup), he might routinely get destroyed by an attack based almost on long diagonals alone. In any case, the opposing bishops are beaming at each other's home squares in the setup, which may be seen as undesirable (though for 12x8 variants with the inclusion of bishops, some sort of tradeoff(s) may always have to be made when it comes to choosing a setup).


This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2002-03-06
 Author: Hans L. Bodlaender. Tandem Chess. 4 player variant where pieces taken from your opponent are given to your partner. (8x8x2, Cells: 128) (Recognized!)[All Comments] [Add Comment or Rating]
Kevin Pacey wrote on 2019-10-23 UTC

Oddly the wikipedia entry for Bughouse Chess (which is given there as synonymous to Tandem Chess or Siamese Chess, unlike in CVP's entry for Bughouse plus Tandem Chess [which notes some differences in rules between the two variants]) does not appear to discuss drops of captured rooks at all, unless I missed it:

https://en.wikipedia.org/wiki/Bughouse_chess


H. G. Muller wrote on 2019-10-22 UTC

I am a bit worried about this paragraph that states a dropped Rook is considered virgin (and thus fit for castling). As far as I know there doesn't exist any on-line server that uses this rule, or any engine that plays by this rule. It is also a very weird rule: when you move a Rook you lose castling rights, and moving it back to a corner normally doesn't restore them. And a drop move is a move like any other.


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