Ratings & Comments

I made an attempt to implement Tenjiku Shogi in Jocly. I even spent some time on the evaluation function. As a result it actually seems to play a reasonable game at 30 sec/move, despite its low search depth. (Jocly's generic JavaScript AI is not very fast.) The web applet can be found at:

http://hgm.nubati.net/jocly/jocly-master/examples/browser/control.html?game=tenjiku-chess

Also, it looks like it doesn't support both sides playing the same army?

Sorry, H.G., it looks like that did not solve the problem.  I am also getting an occasional crash.  I'll email you the debug output.  But when it doesn't crash or make illegal moves, it seems to win the majority of the time :)

A yes, this was something I couldn't test, because WinBoard doesn't accept dressed letters as promotion suffix yet. This was a bit of a subtle bug: the quote suffix was initialized to 0 when entering the MoveToText routine, and then set to a quote if promotion to the 7th piece type occurred before being printed. But by an oversight the suffix had been declared as a static char, so the initialization did not work on every call of MoveToText, but only at program start. So once a move with quote suffix was printed, all promotions would from then on be printed with this suffix. (But WinBoard happily ignored that.)

I uploaded a fixed version to the same link.

Nice!  I didn't have an opportunity to mess with this during the week, but I now have KingSlayer cwda integrated within ChessV cleanly.  It is pretty strong!

I am finding one issue, though.  Sometimes upon promotion KingSlayer sends the wrong notation. For example, ChessV was playing the Clobberers with the white pieces and KS was playing the FIDEs with the black pieces.  When it went to promote, it sent c2c1q' which is not correct.  The Queen is part of its army, not the opponents, so the quote shouldn't be there.  (ChessV then says it forfeited due to illegal move.)

Well, it is difficult to asses whether this capability for a pair to statically create an impenetrable barrier for a King is really important. Actually I think that Wizards can just do it (on 8x8), when standing next to each other in the center. But very often pieces can inflict a 'dynamic confinement' on a King. As long as you have to spend fewer moves to maintain it than the King needs to escape, you have moves to spare for other pieces to approach. Besides, FAD complement each other in a different way: standing next to each other the completely cover a 5x6 area, As a result they can drive a King to the edge with checks, and checkmate it there, without any help. This makes them very, very dangerous.

Even a King + Bishop can dynamically confine a King on boards of any size. The King has to cover the hole through which the opponent threatens to escape, and has to follow the bare King as long as it keeps running in the same direction to renew the escape threat. But when it reverses direction, to try an escape on the other side (which he eventually must, as he bumps into the edge) you have one free move. Therefore a Bishop can checkmate together with an arbitrarily weak piece (as long as that can go everywhere) on boards of any size.

@HG,

Also there is another effect that amplifies pairing bonus or color bonding penalty. The effect of the pair being able to block the king from part of the board. That the same way rooks do on their own. Bishops do that. Two dababahriders to that, and they only cover half the board among themselves anyway. Wizards or fads do not.

Well, this is the whole point of making KingSlayer play CwDA: its playing algorithm can take the effects of color binding into account. But it still requires some thought on what exactly it should pay attention to. The only things I discovered about color binding so far were obtained with Fairy-Max, which doesn't take any color binding into account. It thus might under-estimate the effects. E.g. it approximates the effect of the Bishop pair bonus by making all Bishops worth more than Knights. This biases it against trading B for N in general. Which helps to preserve the B pair, (as it should), but makes it unnecessarily shy in lone B vs N situations (which should be a self-inflicted disadvantage of having a Bishop), and it doesn't prevent it from breaking up the pair by Bishop trading in a BB vs BN situation.

But it still finds an effect of about half a Pawn. I.e. B tests about equal to N, also in 'anti-pairs' (on the same shade), but a true B-pair tests as 0.5 Pawn stronger than B+N or 2N. I also did tests with more than 2 Bishops, and concluded that with 3 Bishops (divided 2:1 over the shades) you get 1 pair bonus, and with 4 Bishops (2:2) you get 2, compared to the simple addition of lone-Bishop values. While one could argue that the number of pairs is 2 and 4, respectively, in those cases.

There is a completely different interpretation of this data, not in terms of a pair bonus, but of a binding penalty. With Kaufman values B=N=325, and the pair bonus=50, so 2B(2:0)=650, 2B(1:1)=700, 3B(2:1)=1025 and 4B(2:2)=1400. These same numbers would be obtained by setting B=350, and giving a penalty of 25 when they are not equally distributed over the shades. The remarkable thing is that the penalty doesn't seem any higher for a shade imbalance of 2 than for an imbalance of 1. So it doesn't seem to matter how much power you have on your strong shade (with non-color-bound pieces you could aim them all at the same shade anyway), but it hurts when you lack power on a shade. This would mean the magnitude of the bonus is not really dependent on the value of the color-bound piece, as it is mainly expressing the disadvantage of absence of a piece. Indeed a preliminary test with Pair-o-Max (a Fairy-Max derivative that takes pair effects into account in a primitive way) suggested that the bonus for Bede was also just 50. (Pitting 2 BD on like or unlike shade versus 2 BmW + Pawn.)

The situation in the Clobberers army should be pretty much like the 4B(2:2) case; after trading one BD or FAD you incur the penalty, which you lose again after you then trade BD or FAD on the opposite shade (making that effectively worth 50 less than the first), but which you would keep after trading the second of the same shade (effectively giving that the 'average' value). This is how KingSlayer treats it now.

But pair bonuses / binding penalties are relevant in the middle-game; in the late end-game you could be in a much graver danger than the penalty suggests, vulnerable to tactics that would destroy your mating potential. Like sacrifycing a Rook for the piece on the 'minority shade' in a 2:1 situation. (Similar to what makes KBNN-KR a draw in FIDE, while KBBN-KR is a general win.) But this weakness would only be fullly exploited if the defending engine would know about it; otherwise it would just randomly trade the Rook for a member of the pair that threatens checkmate, with a 50% probability that it leaves a 1:1 distribution, and will be checkmated later anyway. (Like that it should know in KBNN-KR that it should leave NN, and not BN.) Failing to fully exploit an advantage might lead to underestimation of the value of that advantage.

@HG,

But the issue of an game with different armies where one player has more color bound pairs of pieces is an rather difficult one. The more color bound side has stronger pieces (in order to compensate for the color binding). The issues you mentioned are also strongly related to the fact the the playing algorithm does not understand it. If it does then it will play differently. But the problem is not gone away this way either as the game is now reduced to if early mid game tactics work for the color bound side. And from a game design point of view frankly this is not much. It lacks complexity. 

I'm wondering if the more color bound army has weaker values in the color bound pieces than it's counterparts in the other army, and then it compensates through the rest of the army it can work better. Or is the color bound army, just has more pieces be them individually weaker. Even if this is contrary to Betza's game. This last case also has problems though in the realm of the army with more pieces needing more time for coordination.

So the issue you raise is not that simple in it's depths! And quite likely something that people on the musketeer chess website have not fully considered!

@HG

Your analysys is much deeper (although treating only a nieche of the problem) than any of those made by the guys from musketeer chess!...

Indeed, these asymmetric variants from the musketeer.net website are very unbalanced. Sometimes as badly as playing 6 minors against 6 Rooks in FIDE.

I discovered that the generalization of 'unlike Bishops' in KingSlayer's drawishness detection is not satisfactory. I had it only kick in when both sides have a single piece (plus Pawns, possibly different 1 or 2 in number), and both these pieces are color bound. But from watching games with the Clobberers I noticed it still stumbles in completely hopeless draws with a huge 'naive' advantage. E.g. there was a game where it had Bede and Fad on the same shade, plus an extra passer, versus a Half Duck. All the opponent's Pawns were on the safe shade, ('passively' blocking his own, i.e. without the possibility to offer trades or a majority to create new passers), and the enemy King was blocking the passer on a safe square. All the Half Duck had to do to block all progress was neutralizing any King attacks on its Pawns. Which it could easily do sitting on the safe shade, though its F and D moves. A single Bishop on the safe color (which can also protect from a safe distance) would also have done.

So I guess any situation where you have only to like-shaded color-bounds plus Pawns should be classified as drawish when the opponent has a piece with significant diagonal power (so it can keep a Pawn protected against King attack) that is not bound to the same shade as the attacker. Under some conditions a Ferz would even do (e.g. a Pawn and the Ferz mutually protect each other, and block two opponent Pawns, while the King blocks the third (which is a passer). Tempo moves can be done with King or Ferz, depending on which of the two is far away from the attacking King. No way Bede + Fad + 3 Pawns would be able to beat Ferz + Pawn. While the naive advantage would be about +9 (Bede, Fad being worth 4-4.5, Ferz 1.5 Pawn)! Of course there is no Ferz in CwDA, but there are pieces with F moves. (They are of course worth a bit more, but then you are still at +7 instead of +9.) A or D moves could sometimes do too, when two connected Pawns and the piece cyclically  protect each other (although with D moves you can then only block two Pawns, rather than three).

So end-games with same-shade color bounds can also very drawish even with many Pawns, even when not just Pawns ahead but also in pieces. I guess these must be heavily discounted in order to play well with or against the Clobberers. Having a Knight as defending piece would probably not do very well, though, due to its color alternation. So it would depend on what pieces exactly the opponent has.

Also you had mentioned in the description of the phoenix that the knight cannot be blocked by other pieces. I think you mean the phoenix. Same with kirin!

There is a conglict between the board reprezentation in the picture and the boaard reprezentation in the description of the opening position. For example it is written that the side mover and vertical mover are on the third rank on d3 and h3 but they are actually on 8c and 4 c.

The main rule of game articles on this website is that rules need not cause confusion. This is important!