Comments/Ratings for a Single Item

In the winning conditions, I see no explicit mention of checkmate. It does mention that a player without legal moves has lost. So being stalemated is a loss, and consequently being checkmated is a loss too. This would be clearer to Chess players if it explicitly said that either checkmate or stalemate is a loss to the mated player.

Declaring a winner when the game ends after each player has made 100 moves without a capture or a pawn move is unusual. The rule in Chess is that the game is a draw after each player had made 50 moves without a capture or a pawn move. Since this condition occurs mainly in games in which both players have lost sufficient mating material, I wondering about the rationale for giving the win to a specific side.

Having read your notes, stalemate is a win for the stalemated player. Since checkmate has not been mentioned as a specific win condition, I assume that checkmate, as a form of stalemate, is also a win for the checkmated player. Is this intentional? Or did you make an oversight in not mentioning checkmate?

Wow, I didn't even see this until now. I'm sorry. In both checkmate and stalemate, the last move is the one that checkmates or traps the other player, so the player who is trapped loses. With insufficient material or repetition, the last player to capture would win. The winning condition was intended as an experiment in defining a drawless chess game. I have no idea if it would actually be more interesting or not than any alternative.

The other thing I'm not sure about is the zebras. Their jump fits with the other pieces but maybe it's too far for a board this small?

If my name is required I can add that

In the intervening time, we've had submissions from strong community members who do not have their real names displayed on these pages.  I (and I think we?) still have a slight preference for real names, for the encyclopedic nature of the site, but there are many sites now where site-famous people are later referred to as "user xyz of site abc," so maybe it's fine.

Another thing that changed in the time since your submission: the Diagram Designer.  The use of a period to denote a dot on the board (for movement diagrams) has been deprecated; you can replace them with a pound symbol (#), or a few other options.

My thoughts -

Zebra: The Camel is the more common complement to the Knight.  I think a Zebra is OK on a 10x10 board but would be less mobile than the Knight because more moves would be off-board (although a Camel is color-bound so also weaker than a Knight, but I think this is OK because a Bishop is a colorbound piece that could be considered the complement of the Rook.)  Also, if you keep the Zebra, I think you should keep the name as-is.

No Draws: I'm not sure how advisible this is.  The point of Stalemate is to give the player who is behind something to play for.  For repetition and 100-move rule, at a minimum, the written description needs to be clarified.  It currently says the "last player to move" wins, but your comment says "last to capture".  And for 100-move, do you mean "last to capture or push a pawn"?  That would make more sense.  And do you mean 100 half-moves, like the Chess 50-move rule?  Or do you really mean 100 full moves?  I think that would be too much and I don't see any reason to increase it at all.  Personally, I'd scrap all of this and leave all the victory/draw conditions as in orthodox Chess, but that is just personal opinion.

Yes, I should have included pawn moves in that. I meant 100 full moves but that probably is excessive. 
I think I'll just remove the last to move wins stuff from here. I still like the idea but it might make more sense as a separate variant all by itself. 

My reasoning for using zebras rather than camels is that I think it matches the other added pieces better. The gryphon starts with a diagonal step and continues as a rook, and the zebra's move can be described similarly. It begins with a diagonal step and then continues as a knight, jumping over any occupied squares on the way.

I'll try to fix the diagrams and rules.
 

@Fergus,

Trying to edit a preset for this interesting variant by using the fairychess include file I'm almost done, just need to define the function of the Osprey which is a color-bound aanca, first jumping as dabbabah and then sliding outward as bishop. The following diagram shows its move:

I guess the code for Osprey-Range would look like this:

def Osprey-Range mergeall 
  leaps #0 2 0 
  rays where #0 0 2 1 1 
  rays where #0 0 -2 1 1 
  rays where #0 2 0 1 1 
  rays where #0 -2 0 1 1;

and the Osprey-Desc thus: 

"The %s jumps to the second square on the same rank or file, and then slides outward as a bishop."

Could you please tell me the code for such a function? No hurry; when you can spend some time it's fine. Thanks in advance.

Since it's most similar to the Aanca, let's first look at how the code for that piece works:

def Aanca fn (checkride #0 #1 1 1 and empty #0) 
where #0 0 sign - rank #1 rank #0 
#1 
or fn (checkride #0 #1 1 1 and empty #0) 
where #0 sign - file #1 file #0 0 
#1
or checkleap #0 #1 1 0;

The code works backward, as usual. So it first checks whether the move is a one-space orthogonal move. If it is, it returns true immediately. If not, it continues. To calculate whether it makes a legal Aanca move, it needs three coordinates. #0 is the origin, and #1 is the destination, but it also needs the coordinate for the space on which it changes direction. Unfortunately, variables cannot be assigned in functions. The next best thing is to use a Lambda function that can take arguments. These appear in parentheses after the fn operator. Each one is the same, but each one gets fed different arguments. The second argument is always #1, which is the destination space. The first argument is the space where the move changes direction. Since each destination space falls into one of four quadrants, and there are two possible paths to the destination through a particular quadrant, this information is used to reduce the paths that need to be checked to two.

It first checks whether the move is going left or right, and based on that, it selects the space to the left or right of the origin space as the turning space. It then makes sure it is empty and that there is a legal Bishop move from it to the destination space. If that fails, it checks whether the move is going forward or backward, and based on that, it selects the space ahead or behind the origin space as the turning space. It makes sure this space is empty, and if it is, it makes sure there is a legal Bishop move from that space to the destination. If there is, it returns true, and if there is not, it returns false. I expect that the piece you want can be done with only slight modifications to this function.

How should the underlined parts be read (interpreted)?

def Aanca fn (checkride #0 #1 1 1 and empty #0) 
where #0 0 sign - rank #1 rank #0 
#1 
or fn (checkride #0 #1 1 1 and empty #0) 
where #0 sign - file #1 file #0 0 
#1
or checkleap #0 #1 1 0;

Particularly, what do the underlined  0 's mean?

def Aanca fn (checkride #0 #1 1 1 and empty #0) 
where #0 0 sign - rank #1 rank #0 
#1 
or fn (checkride #0 #1 1 1 and empty #0) 
where #0 sign - file #1 file #0 0 
#1
or checkleap #0 #1 1 0;

The underlined parts are arguments to where, which takes three arguments. The first argument, which you haven't underlined, is the starting coordinate. The next one is a number of files, and the last one is a number of ranks. These values may be negative or positive, and this determines direction. Using these values, where returns the coordinate that is so many files and ranks away in the given directions. This is being used to calculate the coordinate of the turning square, which is one of the arguments for each of the Lambda functions. This uses sign, which returns -1, 0, or 1, depending on whether a value is negative, zero, or positive. When 0 comes first, it will typically be calculating where #0 0 1 or where #0 0 -1. Where 0 is last, it will typically be calculating where #0 1 0 or where #0 -1 0. When the destination is on the same file or rank, and it is not a Wazir move away, it may sometimes return where #0 0 0, which will be the starting space. Since there is no Bishop move to a space on the same rank or file, the function will return false for such a destination, which is correct. For potential moves, it will return false even earlier, since that space will still be occupied.

Thanks. I think we are close to finding the solution!

Then the question is how do we get the where operator returns the 4 options:

where #0 2 0

where #0 -2 0

where #0 0 2 

where #0 0 -2

Is there any other digit to use instead of 0 that fulfills the desired purpose? I mean the zero that I previously underlined.

What is easy to deduce is that the first backward line of code should look like this:

or checkleap #0 #1 2 0;

Is my assumption about the Osprey-Range definition correct?

def Osprey-Range mergeall 
leaps #0 2 0 
rays where #0 0 2 1 1 
rays where #0 0 -2 1 1 
rays where #0 2 0 1 1 
rays where #0 -2 0 1 1;

The range function looks correct. Where the Aanca function calculates 1 or -1, you want yours to calculate 2 or -2. The simplest way is to multiply the return value of sign by 2.

With the following code I have made some progress because the piece already can make the desired legal moves:

def Osprey fn (checkride #0 #1 1 1 and empty #0) 
  where #0 0 * 2 sign - rank #1 rank #0 
  #1 
  or fn (checkride #0 #1 1 1 and empty #0) 
  where #0 * 2 sign - file #1 file #0 0 
  #1
or checkleap #0 #1 2 0;
 

def Osprey-Range mergeall 
  leaps #0 2 0 
  rays where #0 0 2 1 1 
  rays where #0 0 -2 1 1 
  rays where #0 2 0 1 1 
  rays where #0 -2 0 1 1;

However something must be wrong since the program allows the Osprey to be moved as ferz. What do you think is the cause?

That looks correct.

Yes, but then how to explain that the program allows moving the piece like Ferz?

I'd guess it's seeing a 2-leap followed by a bishop move inward as legal?  And that doesn't matter for the Aanca because those same squares can be reached legitimately by a shorter path.

Interesting deduction, Ben. Let's see what Fergus thinks.

You can screen those out with a line that rejects ferz moves. Here is a revision:

def Osprey fn (checkride #0 #1 1 1 and empty #0) 
  where #0 0 * 2 sign - rank #1 rank #0 
  #1 
  or fn (checkride #0 #1 1 1 and empty #0) 
  where #0 * 2 sign - file #1 file #0 0 
  #1
and not checkleap #0 #1 1 1
or checkleap #0 #1 2 0; 

Set. Problem solved. Thank you very much for your help, Fergus.

There is an error in the article probably. When castling is described it says that the king moves 3 squares but this can't happen when castling short as the rook is in the way.

That would not be considered a problem in Chess960, so why should it be considered a problem here? Just treat them as Fischer castlings. The Interactive Diagram I made for this does allow you to move the King on top of the Rook, and interprets that as a castling.

Ok!

The reason for castling being the way it is is that I think it makes more sense if the king ends up closer to the edge of the board.

Interestingly this variant put 3 additional pieces on the decimal chessboard, 3 additional pieces that are, as the matter of fact, old known pieces! Indeed the 3 of them are found in the Grant Acedrex from King of Castile Alfonso X's codex published in 1283.

The Gryphon is the Aanca of the Spanish text, an Arabic word designating an "Elephant Bird", a very big legendary eagle of the oriental tales, able to carry an elephant. Murray translated, a bit wrongly, as a Gryphon (which is another legendary animal).

The Osprey is the Unicornio of the Spanish text, which according to the original illustration designated a Rhinoceros. Consider that in 1283 not a lot of people new what a rhinoceros was and it was identified with the legendary unicorn. I like the idea of a Rhinoceros for this piece that goes deep inside the opposite defensive lines.

The Zebra is the Zaraffa of the Spanish text, obviously a Giraffe, considering that, again in the 13rd century, this beast was a bit frightening for those who had the chance to have seen one. Murray and some others after him had another interpretation of the described move, a step (5,2) instead of a step (4,3) which was a misunderstanding.

http://history.chess.free.fr/acedrex.htm

I also use Eagles, Rhinoceros and Giraffes in Zanzibar but on a 12x12 board.

Maybe, I would have added a pair of Camels, leaping (4,2), to fill c1 and h1. They would fit well the spirit of this game.

Note that the Osprey is not the same as the Grant-Acedrex Unicorno. It is D-then-B, while the Unicorno is N-then-B. The Osprey is the 'conjugate' of the Gryphon, i.e. it has the same move as the Gryphon on the 45-degree rotated grid of squares of the same color.

I agree that this seems a very nice game. And perhaps it would benefit from a pair of Camels as extra minors, to better balance the addition of the quite strong Gryphons (which are close to Queen in value). Even the Osprey seems stronger than a Rook on this large board (even though it formally also is a minor).

Oh thank you HG, my mistake! So, the Osprey is a colorbound piece. Interesting.

My preferred "x-then-bishop" is a 3rd one, W-then-B that I use in some of my large variants (I call it Rhinoceros). The Gryphon/Eagle being F-then-R, I see that pair as counterparts, am I wrong?

Not wrong, because 'counter-part' is a more loosely defined term than 'conjugate'. The latter I have seen only used in the meaning I gave previously. Basically, the conjugate piece is what you get when you grow a new diamond-shaped square in every square corner of the board. Which means it is not a symmetric relation: The Ferz is the conjugate of the Wazir, but the conjugate of the Ferz is the Dababba. The Camel is the conjugate of the Knight. Conjugates by definition are color bound. The conjugate of the W-then-B would be the F-then-DD (as the conjugate of B is the Dababbarider)

In XBetza notation I introduced the term 'rotation' of an atom, which is a symmetric relation: F is a 45-degree rotated W, and W is a 45-degree rotated F. Similarly A <-> D and R <-> B on rotation. So I guess one could say the Gryphon is the rotated 'Rhinoceros', and vice versa. The large Shogi variants often employ this 'playful symmetry', where pairs of pieces in mirror-image positions of the setup interchange orthogonal for diagonal moves of the same range, and vice versa.

I used this W-then-B in my variant Team-Mate Chess, because it is a quite strong piece without mating potential. (And the design goal of Team-Mate Chess was that it would always require at least a pair of pieces to beat a bare King.)

I understand now what you call "conjugate". Interesting notion. I've looked with ZoG what it says about W-then-B, N-then-B and D-then-B (the Osprey here). Like you said, it estimated the Osprey slightly stronger than a Rook on a 10x10 board. On a 8x8, it gives the Rook slightly stronger than the Osprey.

Another question HG, how is defined a major or a minor? It's still obscure for me. Thank you.

I think the consensus definition of 'major' is a piece that, together with its own royal, can in general force a win against a bare royal of the opponent. Pieces that cannot do that are 'minors'. In orthodox Chess the situation is clear: R and Q are majors, B and N are minors. Accidentally this correlates perfectly with piece values, but this doesn't have to be the case in general. The lowest-valued major I could find on 8x8 is a leaper with only 5 moves (the Deva, fFbrFfWlW, from Maka Dai Dai Shogi), which in a FIDE context probably would not be worth more than 2 Pawns. Minors can be more valuable than a Queen. (Think of a color-bound universal leaper, which can teleport to any dark square.)

It of course depends on how the royal moves: in Knightmate a Rook is a minor. Board size matters too: a non-royal King is a major up to 14x14, but a minor on 15x15. And on a cylinder board the Rook is a minor. The stalemate result also matters: in Xiangqi even a Pawn is a major.

It can also be a bit obscure what 'generally won' means. A piece that moves as Rook in one dimension, and as Dababba in the perpendicular one (e.g. vRsD) has mating potential on any size board, except that on even-sized boards there is a fortress draw when the bare King is on the edge that the piece cannot reach. So it depends on whether you can cut off the King from reaching that edge. With the perpendicular move a Dababbarider (vRsDD) you have even better chances to achieve that, and a relatively small fractions of the possible start positions is draw. (But many more than the 0.5% or so that you typically see in a generally won end-game.) With the weaker majors, such as the range-2 Rook, there are also drawn positions where the R2 is cut off from its King, and 'dynamically trapped' in a corner area by the bare King on the same diagonal. There is then no way to outflank the King; it can always get on the diagonal where the R2 moves to, and will approach and eventually attack it when it doesn't move. So I guess in general there still is something like a continuous spectrum between minor and major.

Very good explanation of major / minor notion. Your answer would deserve to be presented as an article on this site.

Thank you, I will think about it. Perhaps I could expand it with some diagrams, or even with links to the Checkmating Applet preconfigured for the mentioned pieces, so that people can try it out immediately.

My main problem is that I am afraid that no one would find such an article, unless they accidentally stumbled on it. (Which, considering the number of articles we have here now, is not very likely.) An alternative is that I would add it to the Checkmating Applet itself, just like I added some general theory on how to checkmate with a pair of minors to the 3-vs-1 Checkmating Applet.

I'd be interested in reading more about the major/minor pieces too, as well as conjugates. I was aware of that concept but didn't know there was a term for it.

The added pieces in this game are meant to correspond to the rook, knight, and bishop, and relate to each other in the same ways those three do. That's why I chose the zebra rather than camels or something else. The knight switches colors so it's counterpart should too, and the zebra's moves are one diagonal step out from a knight's, just as the gryphon's are from the rook's. Also the zebra leaps to the nearest opposite colored squares outside the combined gryphon and osprey moves, like a knight does with the rook and bishop. I don't know if that's a good way to design a game, but I like the completeness of it.

Is there a good word to describe the relation the gryphon has to the rook? The closest I've thought of is expansion.

Daniel, I programmed your variant on Zillions to see how it looks. I was wondering if the castling done by moving the King 3 steps towards the Rook on both side is intentional? On King's side it means that the King goes on the Rook square. Is that correct?

yes, that's correct

I'm trying to figure out how to get the castling rules enforced properly. I really don't understand what I'm doing. Based on this preset https://www.chessvariants.com/play/pbm/play.php?game=Expanded+Chess&settings=default I managed to include the fischer file and make the proper castling moves display as legal, but when I try to actually castle it says You cannot capture your own pieces. I think this has something to do with the post move sections but I'm totally lost trying to understand what needs to be changed.

Apparently that wasn't as easy as I thought since it didn't detect whether the king would pass through check from new pieces, which I also don't know how to fix.

EDIT

I think I found a solution by modifying the fairychess castling subroutine to move the king and rook one space over after castling. It highlights the h2 and h9 squares for moving to instead of i2 and i9 but it works.

Have you tried generating the GAME code with the Play-Test Applet? This should have no problem with a castling where the King ends at the Rook location. (As of today; I noticed there was a bug there in taking back the castling, because the Rook and King were put back in the wrong order, so that the King would turn into a Rook during the legality test.) I temporarily changed the castling rule in the Mighty-Lion preset to do 3 King steps, and this works fine even for K-side castling.

I had tried that before and had trouble defining moves or promotion or something, but I just tried again and was able to make it work. Thanks!

It seems that the sissa-arx-2020-246-116 log is broken, however I happened to discover a strange way to recover it by clicking on the small rectangle below the promotions menu.

As far as I can tentatively estimate, on 10x10 an Osprey (D^B) would be worth about the same as a W^B (referred to by Betza as an Aanca, in his article on evaluating Bent Riders, at least)).

It would be interesting to know, if the Osprey piece type were to be used in a later CV (e.g. a 10x10 one), where stalemate is considered only to be a draw, whether king plus two opposite-coloured Ospreys could generally force checkmate vs. a lone king. I've already imagined at least one mating situation being possible.

W^B is referred as Manticore on CVP. An Aanca is F^R, Gryphon here. This is an old tiring discussion.

The Checkmating Applet cannot do bent riders like Osprey. But it can do a truncated leaping version, like DC. And a pair of these does have mating potential, on 10x10. In the theory of 3-vs-1 mates discussed on the Applet page the Osprey would classify as 'potent', since it can switch its attack from c1 to a1 in a singly move (e.g. f2-f4 or f2-d2). This means it can execute mates in combination with almost anything else that is not bound to the same color.

In fact an Osprey can drive a bare King into a corner together with almost anything on any size board: positioned on an edge it can dynamically confine a King in a corner with the help of its own King. With moves to spare, which can be used to invoke the additional piece.

The Camel and the Zebra never seemed very useful to me. Combining a Camel and a Ferz gives us the Wizard which functions well in many variants, from Wormhole Chess to TenCubed Chess. I wonder if combining a Zebra and an Alfil would improve this game? Sample endgame provided below - the diagram has been cut down to six ranks.

WHITE wins by 1.Nc2 check Kb1 2.(Z+A)e3 mate.

The AZ is a quite strong piece. It does not have mating potential, but is powerful enough to drive a bare King into a corner on boards up to 9x9. So it can pretty much checkmate in combination with anything. Even with an Alfil.

I value thematic consistency, which is the only reason I added Zebras at all. Maybe I go too far with it at times. I do think they serve a functional role too by protecting the edge pawns. An Alfil-Zebra might be an interesting piece, but I wouldn't use it here because that would break the theme, unless the knights were made FN. I also don't want to have only very strong pieces; there are plenty of those already. I used zebras for aesthetic reasons; whether that choice makes for the best game, I cannot say.

Short castling seems to break the interactive diagram.

Short castling seems to break the interactive diagram.

It seems to work for me. What exactly happens that you describe as 'break'?