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I think you misunderstand how engines work. Tree search is simply their way
to make plan. That is by trial and error, discarding what does not work,
rather than by constructive reasoning selectively producing only that which
does work. But the result is exactly the same, and you should not be able
to see the difference by watching it play.

For Chess there are many different engines, with many different
'personalities'. Yet the search algorithm of every engine is almost
exactly te same. It is the evaluation that creates the personality. But the
search is necessary to distill strategic traits from  transient 'noise'
in the evaluation, and thus make the evaluation a meaningful guiding
principle. E.g. like havinga passed Pawn on the 7th rank, (in most cases
very good), which happens to be untenable and will be lost in 2 moves,
making that you are simply a Pawn behind.

If engines storm the opponent's King fortress with Pawns, it is because
their evaluation has some non-linear term in its King Safety, which
penalizes a King as the (say) square of the number of enemy Pawns close to
it. They don't have the slightest idea that a checkmate might likely be
the result. It is the programmer of the evaluation function that new that,
and new that by the time the engine has the Pawns in place, it will likely
see a way to push them that breaks down the opponent's fortress and leads
to mate within its search depth.

The problem with very good engines like Rybka or Fritz is that their
'plans' are completely beyond us mortals, so that we cannot recognize
them as such. While the plans we would make in the same position ar in fact
hopelessly futile attempts that they easily refute and blow to pieces. This
is why it is much more fun to watch games between 'weaker' engines than
Fritz.

Btw, the 3 Alpaca vs 2 Knights match ended in 47.9% after 402 games. This
is really within the margin for equality, so it seem that an Alpaca is
nearly exactly 2/3 of a Knight. (i.e. 215 in Kaufman units, which has
N=325.)

The 2 Guanacos vs 2 Alpacas + Pawn was lost by the Guanacas with only a
37.4% score (434 games). This confirms a Guanaco is worth a lot less than
an Alpaca + 0.5 Pawn, perhaps 235.

I am now doing 3 Guanaco vs 2 Knights and 2 Alpacas vs 2 Llamas (all as
Knight replacements).

I think I do understand how chess engines work. It's obvious that Larry
better understands what I'm talking about. I gave the example of the rook
maneuvre to the king side, in front of the friendly pawn chain. There is no
way that any program, not even Rybka, can calculate any gain from that
maneuvre. He cannot even back up the attack with another piece. So, within
the horizon, it's a useless move. Nevertheless, he just positions it there
and hopes that it can be of good use in the future. But in doing this he
weakens the first rank, etc. But it doesn't matter that it's a bad plan. 
If the human doesn't play well then the computer can have good use of the
rook position. A human player must take measures against it and try to find
a refutation. This is the kind of chess that humans like to play, i.e. a
game which isn't perfect, instead it is full of, perhaps, silly and
refutable plans. But this allows room for creativity. Look at the games of
Adolf Anderssen, for instance. Sometimes unscientific creative chess is
called 'café chess'. It builds on the fact that a brutal pawn storm, for
instance, can succeed although the positional criteria are unfavourable.
After all, chessplayers do succeed in many games with bad plans and bad
openings. It is because it's initiative and creativity that counts. Humans
don't like the perfect and the clinically sterile. They like oil paintings
of Henri Matisse and William Turner. They don't appreciate perfectly
realistic sterile computer reproductions of reality. Such creations are
dead. And so is every chessgame played by today's advanced computer
programs. 
/Mats
PS. How about the Vicuna and the Llama then?DS.

What you describe is purely a matter of evaluation. Such Rook manouevres
(when they are pointless) is typically what you get when you award attacks
on the King's Pawn shield by evaluation points. Because that makes
attacking these pawns a goal in itself, and it will do it even when there
is no follow up (i.e. when the plan was pointless). Without such evaluation
award, it would only go for the manouevre if it did have a follow up that
would be awarded in the evaluation (e.g. breaking down the Pawn shield,
exposing the enemy King) AND it would reach the depth to see it. Awarding
the mere attack on the Pawn shield makes that it will find the devastating
King attack at much lower depth (and thus much further in advance at the
same depth). But it has the problem that it also can backfire, when the
plan is pointless, and would isolate a Rook that was needed badly in
defense on the Queen side (e.g. to stop a passer break through). In this
case it just leads to bad Chess.

This is exactly the problem that I am facing in my new Xiangqi engine,
HaQiKi D. To make it survive the middle-game against strong opponents, it
is essential that it gives high evaluation points for Horses and Pawns
appearing close to the enemy Palace. If it doesn't, it allows the opponent
to amass his material for an attack, until it suddenly sees that there is a
mate within the horizon in every branch, because its strategic position is so
bad that there is no cure.

But it also backfires badly: in end-games where it is behind, e.g. HaQiKi
D has 2A+H, and the opponent has 2A+2E+2H, it might be able to draw by
defending with 2A+H against 2H. (The opponent cannot use his 2A and 2E in
attack.) Trading H vs H would be enough, as 2A vs H is a theoretical draw.


But is loses all such games: his own H is drawn to the opponent's palace
like a moth to a flame, in a completely futile attack on an impenetrable
fortress, defended by 2A+2E, where it could not threaten a checkmate even
against a bare King. And then of course his own King is toast, as 2A is no
defense against 2H. 

And then it makes it even worse: in 'remedy' of attacks by the 2H on its
own defending A, it start to counter-attack the opponent A or E, so that
they are traded. Effectively, this indirect trade is like allowing the
opponent A or E to cross the river and join in the attack, breaking don
further what minimal defense there was. (After trading one A, the game is
even lost even if you could trade Horses, as A vs. H is a theortical loss.)
Incredibly stupid! Virtually every end-game from a slightly inferior
position is lost by HaQiKi D this way.

So allocating material to futile plans is not free: it is in fact losing
Chess. Which means that it will disappear (in this simple
Human-recognizable form) on deeper search, when the search corrects the
initial misevaluation. I.e. when it can see the checkmate can no longer be
avoided within the horizon after trading A, or the opponent's promotion
cannot be stopped after isolating your Rook in front of your f,g,h-Pawns.
If there is any fun to be had watching the engine make such futile
attempts, it is only the fun of pitying the stupidity of your opponent when
he does this.

No, I am discussing AI here, but you seem indoctrinated with the brute
force search algorithm. If all chess programs weren't allowed to search
beyond 4 ply, then programs would need to develop *intelligence* to be any
good, and then computer chess would become interesting and fun again. They
would begin to play cafe chess, like humans.
/Mats

One way to influence a simple look-ahead is to establish goals within the
game. For example(just spit-balling here), the creation of a particular
Pawn structure. The engine would modify its evaluation of the play to
include achieving this particular condition.

Each of these 'goals' might be weighted for both priority and field
condition.

The engine can be easily 'tricked' by having the positive or negative
conditions of these 'goals' affect its evaluation of each plys. The
opposing player's achievement of these same goals can also influence the
evaluation.

There could even be the field position whereby the conditions and/or
priority of these goals may change.

Well, unless you secretly changed topics, we are not discussing AI here at all. We
were discussing Zillions. And Zillions works exactly as I decribed. Even
Humans think far deeper than 4 ply; without that it is not possible to play
any decent Chess, except perhaps at the level of a 6-year-old.

But my main criticism still stands, and is totally independent of any mode
of move productions: you admire moves that are futile, and call them 'a
plan'. While in fact they are just bad Chess, by an entity that does not
properly know what it is doing. You loath 'bean counters' for no apparent
reason other than that they play good Chess.

Well, for deriving piece values I need Chess of a reasonable quality, and
the better the engine, the faster it can play to deliver that quality. If
Zillions needs 30 min per game to reach the same quality as Fairy-Max has at
1 min per game, a 400-game run that I do in a day with Fairy-Max would take
a month with Zillions. That is not doable, as you need mny such runs to
derive the value of a single piece.

The 3 Guanacas beat 2 Knights by 54.8%. Again spectacularly little better
than 3 Alpacas. The small difference between these pieces continues to
amaze me. I should do more tests with divergent pieces, to see if this is a
general trait of non-capture slider moves.

2 Alpaca vs 2 Llamas ended at 50.6%. I forgot for whom, but that does not
really matter as this is equality to far within the resolution of the
test.

I will stop this testing now for some time, as I have to test the opening
book for my engine HaQiKi D, to get it ready in time for the Computer
Olympiad in Pamplona (May 10-18).

There is another important factor than the non-capture slider moves. The
Guanaco has very short capture range, and few capture squares. It is the
combination of these factors that make the non-capture slider moves less
useful. Had the capture range been larger, then the Guanaco would more
often be capable of an forcing an exchange with a light piece. Hence, its
value would approximate a light piece. It is probably the intrusive
character of long capture range which increases the piece's value. If the
enemy piece won't accept being exchanged, it would have to withdraw behind its own lines. Moreover, the few extra orthogonal squares that the Guanaco can leap to are easily controlled on the crowded Western board. After all, the leaping square needn't even be controlled. A piece needs only stand in the way and block the path, while it is not a capture square. So the enemy Guanaco is easily neutralized. 

Since you're working with Xiang Qi, I understand your interest in piece
evaluation. After all, it's much more difficult to define the piece value
in Xiang Qi because it changes very much with the position. Good luck in
Pamplona! 
/Mats

You have to be careful with that kind of reasoning. If the Guanaca had more
captures, it might very wel be worth more than a light piece intrinsically,
and you would not even want to trade it for a light piece. 

There are some pieces for which your reasoning works, e.g. the Camel on an
8x8 board. this is basically a useless piece in the end-game; the side that
has it will almost always lose it without compensation. The opening value
seems to be purely derived by its forking power on a densely populated
board allowing it to be trded for something else. (In the end-game you can
often not even trad it for a Pawn...)

The intrinsic value of a piece is usually determined by how well it
cooperates with the King in positions with several Pawns, to protect its
own Pawns and support their advance, and to gobble up the opponent's and
stop their advance. This is how most Chess games end, so a piece that does
well there has a really large impact on the average performance. Despite
its fairly large number of posible targets, the Camel is totally inept in
this respect: the targets are non-contiguous and mostly far apart, and if
they are not actually off board, they are still too far away for useful
manouevring, once there are ony very few 'centers of activity'. Hoppers
might also best be gotten rid of before the late end-game, although a
Cannon does remain dangerous even with the tiniest supporting material
(e.g Cannon + Ferz makes a won end-game against a bare King).
Grasshoppers definitely get useless very quickly.

But the Guanaca is not particularly bad against Pawns. So I expect most of
its value is intrinsic, and making it more powerful by adding moves would
up its intrinsic value faster than the ease to trade it for B or N.