Deep Junior Engine Parameters
Opening Book Options
OwnBook [Default = ON]
Enables or disables Deep Junior's internal opening book.
Book_file [Default = JR11.BIN]
Path name of Deep Junior's internal opening book. The path (unless fully qualified) is relative to the directory where the Deep Junior program is located.
Book selectivity [Default = 5]
The minimum probability percentage to make an internal opening book move playable. Moves with lower probability will not be played. This option may be used to control the selectivity of the (internal) opening book: Higher selectivity means that only the most common moves will be played. Lower selectivity means that Deep Junior will occasionally select less frequent moves.
Endgame Tablebases Options
Use_tablebases [Default = ON]
Enables or disables the use of Nalimov's endgame tablebases.
NalimovPath [Default = C:\TBs]
Pathname of Nalimov tablebases directory.
NalimovCache [Default = 1]
Size in megabytes of cache used by Nalimov endgame tablebases.
Threads [Default = number of computer cores]
Sets the number of CPU cores (threads) that Deep Junior will utilize when thinking (up to 24 cores). The default is to use all available CPU cores. You may reduce this number in order not to utilize the full CPU resources of your computer(e.g. if you intend to run another CPU-intensive application in parallel to Deep Junior)
Hash [Default = 16]
Sets the size (in megabytes) of the the transposition ("hash") table. The larger the hash table, the more effective Deep Junior's search (although the effect is not dramatic: A doubling of hash table size will result in a moderate increase in playing strength). If you attempt to set the hash size to more than the available memory, Deep Junior will automatically reduce this number, and will send the message "Hash size was reduced" to the GUI interface.
Clear_hash [Default = OFF]
Controls whether the transposition ("hash") table is cleared before every move computed or analyzed. When this option is OFF (by default), some hash table contents from previous moves are retained.
Ponder [Default = ON]
Controls whether Deep Junior will think on the opponent's time. If ON, Deep Junior will calculate its response on the opponent's time, on the assumption that the opponent will play the "Hint" move, i.e. a move that a previous search indicated is the opponent's likely best move. If eventually the opponent plays the hint move while Deep Junior "ponders", Deep Junior will smoothly continue thinking on its own time, and may play immediately if it judges that it thought enough about this move. If the opponent makes a move different than the hint move, Deep Junior discards its pondering and starts calculating its response to the actual move made. If Ponder is set to OFF, Deep Junior is idle during the opponent's time.
MultiPV [Default = 1]
Sets how many alternatives to find in analysis mode: If MultiPV is set to, e.g., 3, Deep Junior analysis will suggest a best move, a 2nd best move and a 3rd best move. The default is to suggest a best move only.
Contempt [Default = 0]
Deep Junior's "contempt of draw", i.e. the extent to which it prefers to continue a game it considers level rather than draw. The value is expressed in centipawns (e.g. 25 is a quarter of a pawn). A negative contempt value means that Deep Junior prefers to draw rather than continue even with a slight advantage. Technically, Deep Junior's evaluates a draw as minus the contempt value. A positive contempt value is useful in avoiding quick chance draws against weaker opponents.
Advanced_contempt [Default = ON]
Controls the way contempt of draw works: When OFF, Deep Junior applies the contempt factor only to actually drawn positions encountered during search. With advance contempt ON, Deep Junior assesses the tendency of every position to be drawish and applies contempt accordingly.
Depth_limit [Default = 60]
Sets a limit on Deep Junior's search depth. The default is Deep Junior's maximum depth. This option may be used to artificially limit Deep Junior's playing strength.
Search Heuristics Options
Search heuristics options control the way Deep Junior's search. All defaults are considered optimal. The options may be modified to experiment with different search heuristics or to limit playing strength.
Null_move_reduction_(depth) [Default = 4]
Depth reduction for the Null Move heuristic. Setting this option to 0 completely disables the heuristic.
Use_half_ply_heuristic [Default = ON]
Enables or disables the "half ply" heuristic (in which a capture & recapture sequence or threat & threat avoidance sequence counts as a single ply.
Use_threat_detection [Default = ON]
Enables or disables the detection of threats while searching. A threat is, for example, an attack by a bishop on the opponent's queen. More generally, a threat is the potential to improve evaluation significantly if the opponent does nothing to counter the threat.
Min_threat_value_(pct) [Default = 100]
When the threat detection heurstic is ON (as it is by default), determines the minimum evaluation gain that counts as a threat. The value is the percentage of the default value.
Use_history_pruning [Default = ON]
Enables or disables the histroy pruning heuristic, a speculative but generally effective method of increasing search depth.
Bad_move_threshold_(pct) [Default = 100]
Sets the minimum evaluation loss that labels a move as "bad", as a percentage of the default value.
Score_drop_threshold_(pct) [Default = 100]
Sets the minimum score drop value that triggers special measures by Deep Junior to attempt to find a better move, as a percentage of the default value.
Evaluation options contrl the way several aspects of how Deep Junior evaluates positions. All defaults are considered optimal. The options may be modified to experiment with different evaluations or playing styles, or to limit playing stregth.
Identify_drawish_positions [Default = ON]
Controls whether Deep Junior evaluates several classes of positions as tending to draw. This evaluation is somewhat speculative, so carries some risk, but is in general considered beneficial to playing strength.
Pawn_value_(pct) [Default = 100]
Sets the value of a pawn, as a percentage of the default value.
Pieces_value_(pct) [Default = 100]
Sets the value of all pieces (except pawns), as a percentage of the default values.
King_safety_value_(pct) [Default = 100]
Sets the level of king safety evaluation parameters, as a percentage of the default values.
No_progress_penalty_(pct) [Default = 100]
Sets the degree to which Deep Junior discounts positional advantages when it detects that no progress has been made in the position for some time, as a percentage of the default value.
Space_value_(pct) [Default = 100]
Sets the level of board space evaluation parameters, as a percentage of the default values.
Mobility_value_(pct) [Default = 100]
Sets the level of piece mobility evaluation parameters, as a percentage of the default values.
Pawn_structure_value_(pct) [Default = 100]
Sets the level of pawn structure evaluation parameters, as a percentage of the default values.
Endgame_king_position_(pct) [Default = 100]
Sets the level of the endgame's king position evaluation parameters, as a percentage of the default values.
Passed_pawn_value_(pct) [Default = 100]
Sets the level of passed pawn evaluation parameters, as a percentage of the default values.
Deep Junior UCI location
The default installation location for Deep Junior UCI and associated files is
"C:\Program Files\DeepJunior\DeepJunior 11.1 UCI"
† Highest performance reached depends on hardware/device used.