Author: Patrick F McHugh
Date: 01:02:29 04/16/05
Go up one level in this thread
On April 16, 2005 at 03:46:34, Ingo Bauer wrote:
>
>Chessbase should be similar, search for "options" or "engine options".
>
>Bye
>Ingo
>
Yes there is some information under the F1 help but it's useless!
Here is the full and exact quote. Please not that I have Shredder 9! It gives
detailed information about Fritz 7!
LOOK:
Engine parameters
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Menu: Tools – Engine – Engine parameters
Many of the engines available have special parameters you can set. To do so,
click the button "Engine parameters" in the engine window. Now, you can change
the settings that affect the playing style of the engine. Each engine will
present the parameters that are relevant to its algorithms.
Usually you can set the following parameters:
Aggressiveness: This influences the playing style and can be set from–2
(passive) to +2 (aggressive). The default value is zero.
Selectivity: Some engines work with a very efficient search strategy called the
“null move algorithm”. Essentially, this allows the program under certain
circumstances to ignore moves that threaten nothing. Thus, it is able to search
much deeper in the position. However, sometimes it is vital to consider moves
that threaten nothing. This happens in so-called “zugzwang” positions, which
rarely occur during games, but play an important role in many studies. Switching
“selectivity” to zero, switches off the null move algorithm, and the program
will solve the studies correctly. But remember to switch it back on for normal
games. It increases the practical strength of the program considerably.
Contempt value: A very strong program can sometimes trick itself into a draw by
showing too much respect for the opponent. On a fast machine, the program may
suddenly start to repeat moves, because it has seen some very deep lines which
is slightly better for the opponent (even though the opponent has no chance of
actually finding the line). To counteract this tendency, we have introduced a
"contempt factor", which essentially tells the program to play on against weak
opponents.
Setting a positive contempt value will cause the program to avoid draws, while a
positive value will make it go for a draw even if it thinks it is better. This
essentially shows respect for the opponent. The value is in hundredths of a
pawn, so setting 50 means that the program will play for a win, even if it
thinks its half a pawn down (which can easily be the case in certain openings).
If the program is playing against a top grandmaster it is usually better to set
minus 50, so it will play overconfidently and take a draw if the opportunity
arises.
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Fritz 8 Engine parameters
Here are the parameters you can set in Fritz 7 to influence its playing style.
You will often be able to achieve a higher performance in specific situations
(e.g., playing very fast games, solving tactical positions or studies). Some of
the parameters are symmetrical and apply to both sides of the game, others apply
only to the side the computer is playing.
Symmetrical parameters
Contempt value: This tells the program whether to accept or avoid a draw. If
the value is positive, then it will avoid lines that lead to a forced draw. If
it is negative, then the program will try to force such lines itself. The value
is given in "centi-pawns" (100ths of a pawn). +100 means Fritz would be willing
to sacrifice a pawn for the draw, –100 that it will accept a draw even if it is
a pawn up.
Selectivity: Fritz uses a search technique that is highly "selective". This
means that instead of looking at every single line of play, however stupid, it
tries to narrow things down to meaningful variations. This allows it to go much
deeper, but it can occasionally miss a highly unusual continuation. This is the
case in positions involving "zugzwang" (i.e., positions in which one side faces
disaster because he is forced to make a move). This can be corrected by reducing
the selectivity value – when solving studies you may want to set it to zero,
since here zugzwang is very often involved. However, remember to set it back to
a higher value for normal games. Otherwise, the search depth will be decreased,
and the program will not be as strong.
Tablebase depth: This determines when the program starts to consult the
endgame tablebases. By setting a higher value, you make the program consult the
tablebases later and less often. This may be necessary if you think that the
tablebase access is slowing down the program. But, of course, you may be
preventing perfect play.
Futility pruning: This is an aggressive method of narrowing down the search.
It allows the program to go much deeper, but it also increases the possibility
that it will oversee something.
Mate threat extensions: This prompts the program to pay special attention to
mate threats. This is quite effective when looking at tactical positions or
solving test suites.
Scale evaluations: This determines how much weight the program will give to
material as opposed to positional considerations. The value is given in percent,
a positive number increases the weight of positional criteria, negative values,
that of material.
Asymmetrical parameters
These remaining values are all given in centipawns (100ths of a pawn) and from
the point of view of the program:
Open files: The program prefers positions with open lines.
Pawn levers: The program prefers positions with pawn levers.
King safety: The program pays special attention to king safety.
Piece values: These change the normal values of the individual piece types.
You can change the values symmetrically for both sides, or asymmetrically with
different values for the computer and the opponent's side. For instance, if you
increase the value of the knight for both sides, the program will look after its
knights, and also assumes that the opponent will do the same. If you only
increase it for the program, then it assumes that the opponent will swap his
knights for bishops.
Save stores the new parameters for the engine. Restore deletes the changes you
have just made. Defaults switches back to the normal parameters.
Please note: The default parameters are the one the programmers consider the
strongest for general play.
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