Ratings & Comments

Does anyone know if 2 fibnifs can force mate against a lone K, say on 10x8 or 12x8 rectangular boards?

While I'm at it, a bigger challenge might be the off-topic question: Can 2 compound pieces force mate vs. a lone K on 12x8, if they are both a lame knight (that is, a Chinese Chess horse) plus wazir movement compound piece?

At the moment I cannot see any newly approved submissions between 0 and 60 days old displayed on the What's New page (as accessed from the CVP home page).

These look like they will work, but they could be optimized better. They repeat the same operations multiple times, and they don't evaluate the most common type of move first. Also, the first or in each, which is the one to be evaluated last, is unnecessary.

Since you brought up the rule in Shogi against checkmating a King in Shogi with a Pawn drop, I checked how I handled it in Game Courier. I handled it similarly. After checking for checkmate in the Post-Game code, my code checks whether the checkmate was due to a Pawn drop, and if it was, it reports an illegal move instead of concluding the game.

Done, and I moved the ASCII diagram to the ALT text of the image.

But then I am not so happy that this requires an alteration of the normal (full-turn) FENs, which would require w2 and b2 stm field in your proposal. I would much rather have it that the exceptional partial-turn FENs would require something special. As the full-move counter is actually completely useless, and in balanced Marseillais the first turn is special in that it only allows a single move, recognizing half-turn FENs by artificially setting their move count to 1 would be OK with me.

The WinBoard Alien Edition would not consider positions half-way a turn not as game positions; when you step through the game later it would always alternate player between two turns, and show the effect of the pair of moves (like it was dealing with castling). Animation of the move might tell you the order.

As to the legality issue: I took the pragmatic approach in my Shogi engines as well as WinBoard: I do not consider Pawn-drop mates illegal, just losing. If checkmate is detected, its scoring depends on whether the previous move was a Pawn drop or not. So even without engine WinBoard allows the user to enter the Pawn drop, which then will end the game for him as a loss. For Shogi this is of course entirely justifiable. But it would not disturb me if Marseillais was treated the same; if we thing it should not be allowed to stalemate yourself after the first turn, just detect the stalemate and declare it a loss if the user elects to play into it.

Okay, Greg, sorry for the misunderstanding. Thousand thanks and good luck!

Ok, I see.  Yes, probably representing positions in the middle of turns would not be common.  But since ChessV considers the legs to be different moves, I needed to do something.  I don't want to break the property that everything has an FEN.

The graphic diagram on this page is very small for some reason.  Don't think it was always that way.  I will fix in a few days if Fergus doesn't.

Hi Carlos,

Sorry, I did not mean to convey that I was done.  Only that I had made progress.  I intend to work on fixing the legal moves display today.

Love the rebuild of chess. It's less a variant and more a unique offering, like shogi as example.

I'd say two things surprised me. In changing almost every piece on the board was there any thought of a different approach to the pawn?

And, of more interest, doing something to save te knight from its 'pasted on feel', the only real disappointment with the game so far? It woul be rare that promotion to a knight would be a better option than a taken piece IMO so I doubt knights get much play.

Perhaps making them a 'Veteran Knight' knight/camel combined move would help.

Or, allowing promotion to a knight on 8 and 9 row, to anything captured in 10th. In that was a knight might be better option as it arrives to the fray earlier.

Just a couple of thoughts.

Greg:

I appreciate very much the effort you make to reinforce the rules of the Symmetric Chess preset, however I wonder if using the preset you suggest will not be more confusing for some people than if we used the entirely uncoded one.

I don't know; it's just a presumption, a guess. In my personal case, I would play without problems with any of those two options.

Certainly, coding the Bishops Conversion Rule is a tremendous challenge.

Yes, FEN is very useful in general. What I was questioning is whether it would be useful to design special FEN conventions for representing game states halfway a turn. I have never seen an orthodox-Chess puzzle like "white mates in four after he has touched his Rook", or people pushing for a FEN field to indicate which piece has been touched. Or a Chu Shogi problem that said "white mates, now that he has captured a Gold something with the first leg of his Lion move. Neither can I imagine why you would want to load a position half-way a turn in a GUI or engine.

More later

The term "royal" in this context specifically means the "capture/mate me to win" property. The term "prince" has been used both for pieces with the King-move but no such property (Tempête sur l'Échiquier comes to mind) and for pieces that serve as a backup royal (Chu Shogi, Tamerlane). Prince is a reasonable term for either, but the clarification is also reasonable.

Ok, I think we'll be in business for a rule-enforcing preset for Symmetric.  I made some real progress.  The display of legal moves doesn't work yet (the legal move display makes it look like the bishop is a dragon horse), but it terms of what it actually allows, it looks like it is doing the right thing in all cases:

/play/pbm/play.php?game%3DSymmetric+Chess%26settings%3Drules

This comment is for Metamachy: as its inventor, I regret that my choice of an Eagle is changed to a Gryphon. It is wrong to think that a Gryphon was present into the Grant Acedrex of King Alfonso X of Castile (1283). No, the piece was an Aanca. An Aanca was an Arab-inspired beast, a giant bird, like an eagle, able to capture and draw elephants in the air. The drawing on the original codex illustrates that. The fault is from the great chess historian HJR Murray who interpretated this Aanca as a Gryphon, another mythical animal. That being said, my choice of an Eagle is in my opinion a better choice for this modern game. The presence of both a Lion and an Eagle, the two most used symbolic animals in heraldry is important to my eyes. I wish you could respect my choice. I don't feel bounded to Murray's errors, despite I owe a great respect to his immense achievements in general. Thank you.

Hello friends,

Two things. I would like to know what was not clear in my description of metamachy? I could make corrections.

Second, it is a bit severe against me as the inventor to write about the Prince "Despite what its name suggests, it has no royal properties". It moves like a King, I think this is a strong royal property. It can be checked, and this is logical, the capture of the Prince should not be the end. A Prince is not a King. Its name is well chosen or I miss something.

Best regards

About the FEN: is this really needed? Why would one ever want to have a FEN for a position after the first move?

Really?  FENs are useful.  For example, the CECP setboard command.  I think the fact that ChessV will give you the FEN for the current position or load a new position by FEN in any game to be a useful feature.

[idea!] Why not use a fraction on the full-move counter if you want to do this? E.g. move 10.5 would mean after the first half of the 10th turn of the player on move

I'm sorry, but I don’t like this at all.  Instead of adjusting the side-to-move from “w2” to “w” and then to “b2”, you are going to go from “w” on move 10, to “w” but on move 10.5, and then to “b” and roll the move counter back to 10?  That is not cleaner than my approach.  And my approach is cleanly extensible to Progressive Chess

It seems to me that a Marseillais Chess cannot be implemented without some dedicated code that would be useless in single-move variants.

It is certainly true that allowing multi-move variants requires extra code.  So the goal was to add this capability in a modular fashion that is not specific to Marseillais.  ChessV has Rule objects which can be plugged in to enable various capabilities.  To support this, I made a special type of Rule called a MoveCompletionRule which handles updating the side-to-move when moves are made or unmade.  Every game must have exactly one of these.  Unless you are playing a multi-move variant, you just leave the default in place which just oscillates between white and black.  Other implementations can do more complex things.  The MarseillaisMoveCompletionRule can be plugged into any game – add it to Capablanca Chess and you have Marseillais Capablanca with one line of code.

It should be clear that you cannot judge the legality of a turn before you have seen the full turn

Well, this is what we are discussing... I wish to avoid that complexity, which I consider unnecessary and possibly undesirable, at least for Marseillais.  But you do have one excellent point, which is:

Take the Shogi Pawn-drop-mate ban.

Yeah.  That’s a problem.  I may not be able to avoid this issue long term since I deffinately want to be able to support Shogi.  I think that rule did cross my mind previously and I immediately pushed it to the side so as not to give myself nightmares.  Say, I wonder if Zillions can handle that rule?  I bet it can’t.

The other examples you give, like Paco Shako – are probably not going to happen – at least not unless other programmers start assisting me.  ChessV is now up to 400 files of source code.  It’s a ridiculously ambitious project for one guy in his spare time.  Some things just aren’t going to happen.  Unless I win the lottery.  Or find a wealthy benefactor.

The reason I mentioned QS was because I assumed this would be required to detect the fact that the previous ply exposed the King

That’s not how I am handling it.  One of the messages a Rule object can accept is MoveBeingMade – upon which it can update internal information (in the case of the castling rule or en passant rule), but it can also rule that the move is illegal.  The Checkmate rule handles MoveBeingMade, checks to see if the king is attacked, and rules the move illegal if it is.  And, determining if a square is attacked is also routed by message passing.  Butterfly Chess includes a CaptureByAdvance rule which handles the Advancer’s capture ability.  So the Checkmate rule handles MoveBeingMade, fires off IsSquareAttacked messages, which are picked up by the CaptureByAdvance rule.  So Butterfly Chess has both capture-by-advance and check/checkmate/stalemate without either Rule object knowing anything about the other!  Beyond that, support for Butterfly comes entirely from the scripting language - no C#, entirely plug-and-play. Computationally very inefficient, hence my lousy nodes-per-second, but that’s how ChessV is able to play such a wide variety of games and how I am able to add support for new games very quickly.