HIARCS 14 UCI Chess Engine Information
The HIARCS chess engine has many files and parameter options which can be modified to change the playing style and strength of the chess engine. We believe the default options were the best known at release but there are some interesting possible improvements!
Below you will find the options available in the HIARCS 14 UCI chess engine and a description of their affect on the engine. Any defaults are in parentheses and explained in the text.
Threads (Default Max CPUs <= 16)
This option is only available in the Multiprocessing
version of HIARCS (Deep HIARCS). It allows you to configure the number of threads the
HIARCS chess engine will use during its thinking. The default is to utilise as
many CPUs as available up to a maximum of 16. We hope to raise this limit when we
have verified the program on more CPUs. If you wish for example to run
HIARCS 14 on only one processor you can set this value to 1.
Busy Threads (ON)
This option when set makes HIARCS utilise threads as always busy - that is to
say they do not go to sleep when no work is available.
Position Cache Options
The hash table is typically large area of memory used by
the HIARCS chess engine to record previous calculations to speed up future
computations. This can be set from 1Mb to 2048Mb in 1Mb steps. You are
recommended to use 50% of your machines physical RAM for Hash tables. Please
check that your hash table size setting does not cause disk activity. If so
HIARCS will run significantly slower - in this case please decrease the hash
table size and try again.
This allows you to clear the hash table of its
information. This option does not normally need to be used.
Retain Hash (ON)
This option enables HIARCS to maintain its hash table
between moves and this improves its play as well as its learning ability and
analysis. The default is ON.
Position Learning (ON)
This setting allows HIARCS to learn from the games it plays or analyses. This can improve its play in future games. The default is ON.
Search and Playing Style
Playing Style (Active)
HIARCS has three different playing styles, namely,
Active, Aggressive and Solid. The Normal style is the default and believed to be
The HIARCS search is selective - it tries to cut out
irrelevant moves and variations. You can set the selectivity from 0 (no
selectivity) to 7 (extreme selective). The default and strongest setting is 7.
Optimistic Search (ON)
This setting tells HIARCS to search with a more
optimistic view typically leading to deeper searching. In wild positions and
tactical tests it may be found that an OFF setting is better. The default is ON.
This setting makes HIARCS look deeply at tactical
combinations. This setting can help HIARCS find combinations sooner. The default
Hyper-Modern Play (ON)
This setting make HIARCS play in a more Hyper-Modern
style. The default is ON. This setting in the past has sometimes been shown to
increase the strength of HIARCS. Previously HIARCS 11 had this option OFF.
Hiarcs Draw Value (0)
This setting enables you to specify in centipawns if HIARCS should favour a
draw or not. Positive numbers means HIARCS will prefer draws, negative it will
try to avoid them. This is a dangerous option expecially in endgames. The
default is 0 which neither likes or dislikes draws. Special note: The HIARCS
style normally means it naturally avoids draws and plays actively.
Swindle Opponent (ON)
In positions which are normally drawn (for example K+R v K+B), the swindle setting tells HIARCS to keep pressing for the win if it is the stronger side. This is most applicable against human opponents or computer opponents who do not use endgame tablebases. Default is ON.
Opening Book Options
Own Book (ON)
This setting allows HIARCS to use its own engine opening book. HIARCS 14 uses the book named Hiarcs14aBook.hcs located in the HIARCS data folder. HIARCS 14 uses book learning. The default is ON and is clearly the best option.
Our tests have shown the own engine tournament book
combined with the unique learning features are more than a match for any other
commercial opening book we have played against.
This option option string is read only and tells you the
book name used and if
the book loaded ok or not. You will get a warning if the opening book is
read-only as that means book learning cannot operate. If HIARCS cannot load or
read the book you will get an error here.
This setting informs you of the number of positions in
the book which is loaded. The tournament book has over 5 million positions. Please use the Tournament book for
serious chess play.
Book Style (Tournament)
This setting allows you to choose the style of the
opening book from Wild, Surprise, Dynamic and Tournament. Please use the default
"Tournament" for serious chess.
Book Learning (ON)
This setting allows HIARCS to use its experiences with
the current book to make decisions about which moves to make from the book.
HIARCS has clever book learning so please use it!
default is ON and clearly best.
Endgame Tablebase Options
CPU Usage (100)
This parameter enables you to set the % of CPU that HIARCS will use. By
default this is 100% for maximum strength. I have found it useful when using
HIARCS for analysis under Chessbase GUIs on Windows Vista to set this to 98 or
99% so that the GUI is more responsive to user requests. In game or match play
it should be set to 100%.
Use Tablebases (Normally)
This setting allows you to choose how often HIARCS accesses the Nalimov endgame tablebases. The available options are Often, Normally, Rarely and Never. The default is Normally.
This sets the amount of memory used to cache endgame tablebases. This value should be about 1/8th of the hash table setting for optimum performance. Typically this is between 1Mb and 256Mb with 32Mb a commonly used amount with a 256Mb hash table.
The is the location of your endgame tablebases. HIARCS UCI can use up to 6 piece tablebases.
This option when ON makes HIARCS play Fischer Random Chess or Chess960 as it
is perhaps better known. The default is naturally OFF.
This option when ON makes HIARCS weaken its play down to the Elo level
UCI_Elo. The default is naturally OFF.
UCI Elo (2330)
This enables you to select a limited strength HIARCS based on a specific Elo
rating. This option is only applicable if the UCI_LimitStrength option is set ON.
GUI Time Lag (OFF)
Some GUIs deduct from the engine clock the time the GUI consumes updating the
display. This can mean that for each move the GUI takes 50 milliseconds or more
extra time away from the engine leading to time trouble for the engine in that
GUI. We noticed this in the Shredder UCI GUI. However, in the Chessbase Fritz
and Arena GUIs we did not see such problems. The default is OFF. It should
be OFF for all Chessbase GUIs and Arena. When using HIARCS UCI in the Shredder
UCI GUI it should be switched ON.
Verbose UCI (OFF)
Some GUIs seem to react very slowly to UCI output. This option when OFF reduces the amount of information which is output to the GUI and can make the GUI more responsive. We noticed when this option is ON the Chessbase GUIs become slower during engine use so we recommend this option is switched OFF especially in Chessbase GUIs. The Shredder UCI GUI is much better at handling verbose UCI output. The default is OFF.
"generally I use
HIARCS." - Five time World Chess Champion
Vishy Anand, in a recent interview when asked what chess program he uses to
World Chess Champion, Vishy Anand, used "Powerful" HIARCS machine in preparations for his 2010 & 2012 world title matches
"This level of service is one other big reason to buy HIARCS." - John Jackson
† Highest performance
reached depends on computer used.
Computer Chess Software
with world class chess engine playing strength.