Comments by HGMuller

Well, what you propose is not backward compatible with what we have, so that rules it out no matter what. I think repetition through parentheses is more flexible than on individual modifiers, and can achieve the same thing. KaKaaK can already be written as (a)2K, and if all steps should capture as c(ac)2K, or (ca)2K if the last step does not have to capture. Exactly 5 Wazir moves can simply be written out in full aaaaaW. The Ubi Ubi can already be written as (a)N.

But I want to get rid of the a notation (which was the core of XBetza), which quickly gets very obscure. And the need to express everything with a single atom is often very cumbersome, requiring many mp intermediate steps for what really is a single (but incommensurate) leap. The bracket notation, which is somewhat similar to a very old proposal that I called Betza 2.0, would solve all that. But I never think there was any formal specification of it, which should be a first step. So:

Betza 2.1

All extensions of XBetza apply, except that the a modifier is not used for chaining, y does not exist, and g exists only as legacy from original Betza notation (i.e. in a single-leg move describing a grasshop).

Complex moves must be surrounded by brackets [ ]. Within the brackets there can be a number of simple Betza move descriptors, each describing a leg of the move. These can be separated by hyphens - or question marks ? . The meaning of a question mark is defined as

[A?B] = [A][A-B]

The hyphen indicates chaining: the legs must all be made one after the other, the next one starting where the previous one ended, each satisfying the conditions that their Betza notation specifies. The default mode for non-final legs is m. This doesn't exclude the leg descriptions from being compounds:

[A-BC-D] = [A-B-D][A-C-D]

Directional modifiers in continuation legs are interpreted relative to the preceding leg, where f is default, and means "as much in the same direction as possible". Since legs need not use compatible atoms, it is not completely trivial what that means. So to be more specific:

• Diagonal after diagonal and orthogonal after orthogonal: f = exactly the same direction (W system).
• Diagonal after orthogonal and orthogonal after diagonal: f = two moves, deflecting 45 degrees (F system).
• Orthogonal after oblique: f = in the direction of the longest orthogonal component (W system).
• Diagonal after oblique: f = in the same quadrant (W system).
• oblique after diagonal: f = two moves in the same quadrant (N system).
• oblique after orthogonal: f = two moves closest to that orthogonal axis (N system).
• Oblique after oblique: f = in the same octant (K system).

The use of an 8-fold radial (pseudo-)atom like K or Q after oblique might result in undefined behavior, unless all directions are allowed. After diagonal or orthogonal atoms these use the K system, with f is in exactly the same direction.

In this system a is a new directional modifier for use in continuation legs, meaning "all directions, except to squares that were already visited earlier in the path". And 'the path' is supposed to also contain the square of origin.

The bracket notation always specifies completely (i.e. 4-fold or 8-fold) symmetric sets of moves. If the use of compound legs allows non-congruent paths, each such path will be included in all its orientations (including reflections). That means directional modifiers on the first leg are not allowed. To define a subset of these moves, directional modifiers should be placed before the brackets.

Paths that completely stay on one diagonal or one orthogonal will be considered of that symmetry; other paths are considered oblique. Directional modifiers in front of the brackets will be interpreted in the symmetry class of the trajectory that is subject to it. For oblique moves the direction in which the path first steps of an orthogonal or diagonal determines in which of the two adjacent octants it belongs. E.g. for a Ship, the symmetric move set is that of a Griffon ([F?R]), and the first oblique squares on its allowed paths are that of the narrow Knight (vN). The Ship is thus v[F?R].

Consequence: describing trajectories of different symmetry in one bracket notation can be asking for trouble if you want to make a selection. If you write fr[R?sR] the brackets describe both orthogonal and oblique moves. For the Rook moves fr means forward or right, but for the hook move it means the forward one of the rightmost pair, which would be first right and then forward.

Prentheses can be used to indicate the text they enclose can occur zero or more times; a number behind the closing parentheses indicates the maximum number. E.g. [(pR-)cR] is a Rook move that must capture, but can hop over arbitrarily many occupied squares to do so.

Burning: trajectories of 'flames' can be appended as extra leg(s) within the brackets, separated from the real move by a semicolon ; rather than a hyphen. The piece would in any case end up in the destination specified by the last leg before the semicolon (to which the rules for a final leg apply). From there any valid move of the burning spec (interpreted as continuation legs of the move, as far as directional modifiers and i legs go) would then burn its destination. E.g. [Q;cK] would be an Advancer, burning the square just beyond the one where it stopped, [Q;acdK] would burn all pieces (friend and foe) adjacent to the destination, [Q;ibQ-cK] would be a Withdrawer, and [R;ap'D-bcW] would be an Ultima Pincher Pawn if p' indicated friendly hopping.

Planar moves: (proposal) these could be indicated by two moves within brackets separated by a period. The meaning of [A.B] would be that any move consisting of zero or more repetitions of a move described by A and a move described by B would be valid if any move with a smaller number of such repetitions of A and/or B would end on an empty square.

Well, the way you implemented it in the Diagram would morph the King to a non-royal piece, which it would consider a loss. To make it work as you described, you should define a royal and a non-royal version of each piece type, and let the King morph to the royal types.

I see that the regular PTA is not able to convert the morph parameters to GAME code. (I suppose originally this made sense, as there is also no way to specify morphs when you set up the variant.) You tried to use promotion to get the same effect, but the GAME code cannot specify promotion choice per square, just per entire rank. What you did would allow all pieces to choose to what they promote to, on each square of 5th rank (including promotion to enemy pieces!).

Fortunately the newer version of the PTA is nearly finished, and it can translate the morphs to GAME code.

That's a good idea. The 'Classical' representation also suffers from the flipping problem, and this could be used there too.

Well, it would be very easy for westerners and Japanese alike to see whether the traditional glyphs for chess pieces are printed upside down, so there is just as little need for drawing tiles around them as it is for the Japanes to draw them around ther kanji. And space is more cramped on a computer (or telephone!) display than on a newspaper page, so that would be another important reason for not drawing them.

Simulating the experience of playing across the board helps??? To chase people away, most likely! Playing Shogi across the board is an absolutely horrible experience. It is the main reason why the Dutch Chess Association has about 150,000 members, and the Dutch Shogi Association only 56...

Well, just make a Diagram with twice as many pieces, making sure that the piece you want to use as royals have different IDs from the non-royals. (Game Courier does not like it if pieces have the same ID.) In the new PTA you can specify the royals (through "Specify more rules"). Then make sure the King morphs into the royal pieces.

Ughh, that would be a problem indeed. Better use a semicolon for the burning then.

Only for westerners with enough experience using Japanese pieces.

I was not talking about japanese pieces. The issue is whether people without any experience whatsoever could see the difference between this  and this , or whether they would need help of a surrounding pentangle before they could spot the difference. Seems to me the pentagle is totally useless. Of course it would be far easier still to see the difference between this  and this .

There is no accounting for tastes, but some representations are just objectively inferior. This could be measured by how long it takes people not familiar with any of the representations under test can see the solution to trivial problems (like "what is the best capture in this position", while PxQ is possible). That there are people that like the inferior doesn't make it any less inferior.

Also, I'd wonder whether directly backwards is part of the default, or would have to be added.

Good question. It makes less sense to exclude it here. OTOH, normally this square has to be empty, or it would have blocked the move. So it only becomes an issue for a burning Grasshopper move. As it seems quite unlikely anyone would use that, there seems little harm in excluding it. Just for uniformity with other continuation legs. It is easy enough to add it through ab, while it would be very hard to exclude it.

the description there doesn't match up with the explanation that I recall being given to me.

Well, I tried to generalize it. But I think I blew it, because I was thinking in terms of steps rather than moves when I wrote it.For the conventional 'orthogonal planar move', which we would write here as [vR.sR], the point is that the steps set up a grid (in this case containing every board square), and that you only have to consider what is on that grid. But (on an empty board) every square of the grid could be reached by zero-or-one move of the first kind plus zero-or-one move of the second kind. The area spanned by the move (which must be empty) consists of all squares that could be reached by fewer or shorter moves of both kinds.

I used the dot because I saw it as a multiplication. A comma could also be suitable, if you see it as coordinates.

The Ubi-Ubi is of course a sick piece. The problem is that the current implementation of the I.D. tabulates each angular realization of a given move, and for multi-leg moves that can freely change direction that quickly explodes. Even the Tenjiku area move, (a)2K, produces some 500 trajectories.

In my Symbolic set, it's the only thing that will distinguish between Pawns or Gold Generals on each side.

Well, that just shows how unsuitable the set is. You would not have that problem if one of the two players used black pieces.

Also, in the western set I criticized, the Silver and Gold General images would be too unfamiliar to players for them to easily tell which is on which side right away if only orientation was used to distinguish them. When I first looked at them, it seemed like they were oriented differently than the other pieces, and it took me a while to figure out that they probably represented epaulettes on a shoulder.

The point is of course that orientation is not used to distinguish them at all. They will never be displayed upside-down, but one is white and the other black. The stars are just to distinguish the 'rank' of the generals; the more stars the higher. And this number happens to coincide with the number of non-forward moves, which offers the oppotunity to place them in a pattern that is slightly mnemonic for the direction of these moves in the white POV.

Not if the move is a leap. Imagine, for example, a Flame-ingo with [CX;KD].Or, probably more to point, a piece with K[T;K] -- or should that be K[T;abK]?

In the former the burn would go to all 12 squares, as none of the KD steps is perfectly aligned with CX. In the second case one of the moves would go exactly in the backward direction. Although it doesn't seem a disaster having to write ab, I guess it shows that there really is no reaason to forbid moves with another stride. So I will change the definition to that it should not go back to the previously visited square on the path.

That reminds me that in XBetza at some point I defined it as not being allowed to return to any previously visited square, to prevent that aaK could make a turn pass by triangulating. Of course this was pretty much unimplementable. Now as the Ubi-Ubi (which basically has an unlimited-range area move with Knight steps) shows, area moves really need a dedicated generator if you want to treat those efficiently. (As is very important for the AI.) There is just too much overlap between them. (a)2K has 456 possible realizations, but these reach only 49 squares. So each move is generated some 9 times on average. A good algorithm would be to tabulate first which squares you can reach in one step, and then from all of those take another step to tabulate those you can reach in two steps, eliminating duplicats at every stage.

Yes, and that is exactly what makes over-the-board Shogi such a terrible game. That convention is highly inferior.

Bracket notation is a proposal for future improvement, and basically not implemented. A few cases representing commonly used pieces such as Griffon are recognized, and handled by a pre-processor that substitutes the corresponding a-notation. The S is apparently not amongst the recognized cases. (This might be easy to fix.)

Range limits on hoppers has always been a problem in XBetza, because you would really need two ranges: one for before, and one after the mount. The rules for range toggling (triggered by g or y) are such that the specified atom + range count for the first leg, that finite range turns into infinite, and infinite into 1. So gQ4 means up to 4 steps to the mount and infinitely many behind.

Bracket notation would solve this, by allowing you to specify a range in each leg. But it is not implemented yet.

Reusing an existing symbol has little advantage if you have to introduce a new symbol to resolve the ambiguity it causes. IIRC 'halfling' is a (flexible) range specification, so it would be more natural to indicate it as a (non-numeric) suffix than as a modifier prefix. I would suggest the % sign, as the actual range should be a fraction of the free path. We could even give different meaning to W% and R%.

As a symbol on its own checking for a piece is already done by p. If a combination of symbols is to be used for specifying whether it should be friend or foe, I'd rather use p' and p" than a t. The quotes could be used to diversify other modifiers as well. E.g. c' could be friendly capture, and c" friendly or enemy capture. Than d could be retired.

Indeed, screen = mount = platform. Two platforms you can already do by [pB-pB-cB] or pafpafcB.

Anyway, I disagree with you. I find the Shogi convention better for Shogi and the Chess convention better for Chess. At least with computers we can let players use whichever convention they prefer.

Well, as I pointed out, it is not a matter of opinion. What is a better representation for playing a game is a verifyable fact, measurable by the average rating drop or raise people would get when having to play with one representation or another. E.g. representing all pieces by empty squares (aka blindfold chess) usually greatly degrades the rating of non-GM players, and can thus be considered an unsuitable representation for playing Chess.

And 'disagreeing with facts' is also known as 'being wrong'.

For people that want to experience the difference between using pictogram and tile pieces, I set up a simple speed test cq dexterity game here.

The idea that Shogi and Chess would have different needs does seem rather inconsistent, as they are practically the same game. I have difficulty identifying any aspect of either game that would cause such a difference.

But it is indeed good that people can choose their representation on a computer independently of that used by the opponent. If there is at least one suitable representation amongst the choices.

Well, bracket notation is currently only implemented for two-leg moves: it tries to reduce those to a commensurate atom, and ignores all later atoms, except their leaper/slider nature for determining if a y should be inserted. So when it works it is basically coincidence.

If you assign a new move to another piece, you can see which XBetza the preprocessor produced from your bracket notation. Which in this case is: RyafufafcfabR . So you see it did understand that the move could end at R, and it did understand there were 4 legs (3 as), it did understand it had to switch from slider to leaper after the first leg. It got a bit confused about the directions, because you added an f where no f was really needed, because that is already default. And you did that after a mode modifier (while I always do directional modifiers first), so that it did not notice it. Hence it adds a redundant f before the u and c. But I don't think that would hurt. It did understand that two continuation legs were f, and the 3rd b.

What it did not understand is that the 4th leg was D. Because it never looked at it, other than classifying it as a leaper, so that it should not toggle back the W to R. So it was close, but no cigar...

Well, I have no Chu-Shogi pictograms on tiles or any other game that has that. Furthermore, to program such a test with reasonable effort requires sets that have compatible piece names for sufficiently many piece types. I don't think we have that here.

But this latest test shows that the pictograms themselves offer almost zero help, if they have all the same color. You would decide almost exclusively based on the surrounding tile, without looking what is inside. And then it would not matter much whether the inside is kanji or pictograms. And the kanji tiles also did not do very well.

This would indeed be hard. One way I could see it done was introduce a special symbol as repeat limiter similar to what i does for slider continuation legs, and thus means "as many repetitions as there were in the previous parenthesized group". Suppose that symbol is $, you could write [(mpW-)pW-(mpW-)$cW]. It is a sort of orthogonal Equihopper.

I meant the 3D pieces for other games. Flat pictographic boards feel generally easier than any alternative.

Ah, OK. Indeed, it could be that statue-like pieces in 3D are not optimal at all. But even a flat pictographic board lying flat between the players would suffer from some similar problems. I guess the traditional equipment suffers from the boundary condition that it must treat the players equivalently, just as traditional Shogi equipment suffers from the fact that the pieces have to be usable for both players, and must be able to promote.