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Zitat von Tibono (Beitrag 116771)

With the Super Constellation, the behavior follows another way: after a few seconds the score gets steady (due to the selection of the best move so far) and from then, the light byte value does not change any more. Along with the computing time and depth, the heavy byte may change (an in-depth capture being discovered), but the light weight byte is not any more changed by any positional concern. As far as I could check, it only may change along with a change in the material score, which I assume is a change in the root best move so far.

To my understanding, this reveals a PSH strictly applied either at root or at low depth in the search tree, providing a positional score per root move, followed by a material trading evaluation only for the rest of the tree search.

Hi, I've been following this thread with great interest.
Thank you all for all amazing information and research in this thread.

I just want to share some information I have gathered on the "PSH" topic.
(Maybe there already is a Super Conny thread about this, but I've not read that, sorry.)

From Kittinger: https://www.talkchess.com/forum3/vie...opic_view=flat:

"Had to research PSH as I suffer from TMA (too many acronyms). 'pre search heuristics' involved recognizing certain specific characteristics and feeding bonus/penalties
into specific moves in the root position move list (ply one move list).
Most famous example of course is the bxh7 sac, although as I recall there were a couple for center pawn sacs when danger of getting constricted to death.
These rules were done from white POV then list run through and swapped for black POV.
With limited processing and search depth, at the time it seemed necessary to look for some typical chess themes cheaply
(applied only for the plyone moves) as opposed to testing lots of positional features deeper in the search.
Obviously there are all kinds of negatives to this approach, but in practice worked out reasonably enough.

As I recall, another short cut which led to interesting play at times had to do with long strings of checks which were not repeats.
With Super Conny at least, these were given a bonus as this was before all the more intelligent extensions for checks had been worked out
(and I think ram space only allowed something like 18 ply maxdepth).
Idea was that such strings of checks might be leading to forced mate or gain of material which program did not have depth to see actual end of."

"Quite a few of my programs had both ply 1 move bonuses/penalties and PVT bonus/penalties.
I spent a lot of time trying to move the PVT values deeper into the search w/out much success.
Never tried that with the PSH though, might work, could have then played to actually achieve or avoid the sac like positions.
The bxh7+ effectively added 5 or 6 ply of depth.
As I recall, the rules for that one required (from white POV) wp on e5, wn access to g5, wq access to h5 or h4. bp at e6 and g7 and no bn access to f6.
Something like that, it was pretty specific rules to give sac high chance of succeeding.
At the time, none of the micro chess programs had a prayer of seeing deep enough to play the sac, even though fairly weak humans could find it.
However, with one-reply to check and singular extensions, I think the sac can be found at much shallower depths, making the whole PSH less valuable."

From Chess Life #11 1984, page 26-27+82: https://uscf1-nyc1.aodhosting.com/CL...84/1984_11.pdf

"Kittinger used a unique approach. He
deliberately simplified his tree-search
evaluation down to an absolute minimum,
coding it very tightly so that it would execute
quicldy. Although this evaluator is not very
smart positionally, it is excellent tactically,
and fast enough to carry out an extended
quiescence search.
To give his program positional knowledge,
Kittinger added an initial positional evalua-
tion routine that examines the board position
before going into the tree search. The pro-
gram assigns "strategy values" for each of
the legal moves, depending on how much
sense they make positionally. It also
values of the pieces depending on posi-
tional considerations, and assesses the
values of the squares pieces are placed on.
This initial evaluation is quite elaborate com-
pared with the evaluation done at the tree-
search level by any microcomputer pro-
gram, and it takes much longer to execute.
But this does not slow the program down,
because the initial evaluation is executed
only once, at the beginning of the search,
while other programs must do positional
evaluations many thousands of times.
Later in 1983, Kittinger extended the Con-
stellation program, adding many more posi-
tional factors to the initial evaluation
routine, endgame improvements, and a
greatly enlarged opening book.

Opening Book. The Super Constellation's
opening book contains a remarkable 21,700
moves, about one-fifth of the lines appearing
in boldface type in the Encyclopedia of Chess
Openings Although this standard opening
book (some variations are 22 moves deep) is
more than enough for most players, the pro-
gram's author has recognized the special
needs of the strong player with an interest in
opening theory. The machine accordingly
features a special learner/trainer mode,
which allows you to "customize" its opening
book with up to 1,200 additional moves.

During the game, both
machines will show you at what depth the
program is searching. For the Super Con-
stellation, that can be up to 20 or 21 plies in
infinite modes; at tournament levels, it
searches to five or six plies in the middle-
game, 10 or more in the endgame.

HIGH-POWERED FEATURES
The Super Constellation s special playing
features illustrate what the future holds in,
chess computers. For example, how many
human players can mate with Bishop and
Knight? This machine can carry out that
mate — as well as all the other basic mates-
at five seconds per move!
Super Constellation's play in pawn end-
games is also quite impressive by computer
standards. To begin with, the program
understands the "square of the pawn" rule,
with such refinements as whether a King
can help its own pawn by taking squares
away from the opposing King. This helps the
program to accurately evaluate threats
created by passed, or potentially passed,
pawns. Super Constellation also knows to
move Rooks behind passed pawns and to
blockade passed pawns.
An unusual and impressive feature is the
machine's ability to sacrifice a piece for a
pawn to reach a drawn endgame.
In the middlegame, Super Constellation
plays an active, tactically oriented game. It'
unique initial evaluation routine also
enables the program to formulate and carry
out positional plans. This does not work
perfectly (neither do my positional plans),
but it greatly strengthens the program's play
and also makes it an interesting opponent
with a relatively "human" style. This initial
evaluation routine contains about 160
specific instructions, which is quite an ac-
cumulation of chess lore for a computer.
Half of these instructions relate to pawn
play, half to play with other pieces. The total
chess knowledge contained in this routine
vastly outweighs anything that could be put
into an evaluator function that must look at
each end position in the search tree.
About 25 percent of these instructions act
negatively; that is, they prevent the machine
from making typical silly "computer —.
moves." For example, many programs tend
to play a move such as ... Bb4 + , "thinking"
that the only reasonable reply is Nc3. Some
programs will even do this with a piece "en
prise, losing after the unexpected reply
c2-c3. Thanks to its initial positional evalua-
tion, Super Constellation avoids this and
similar blunders.
The other 75 percent of the instructions
drive the machine into a search for active
play. Slow maneuvering games are still |
beyond any computer's abilities, but Super
Constellation has some impressive capabili-
ties in more active positional operations. For
example, it knows how to play a minority at-
tack in the Exchange variation of the
Queen's Gambit Declined, and it seeks
pawn breaks to open up a position.
A really impressive feature of the pro-
grams middlegame play is its ability to make
sacrifices on positional grounds. These are
not always perfectly sound (neither are my
sacrifices), but they usually are, and they
nearly always lead to difficult and in-
teresting tactical play. The program knows
how to make the stock sacrifices on e6 in the
Sicilian, and on h7 in the French when Black
lacks a Knight at f6. And it knows how to
follow through on them. It also recognizes
opportunities for positional pawn and Ex-
change sacrifices by either side, and em-
phasizes fast development in openings —
when "out of book" the program will give
back a gambit pawn for development."

/Lars