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Welcome to the world of Crafty! (version 15) ----------------------------------------------- Crafty is nothing more than a long-time hobby of mine, dat- ing back to Blitz and later Cray Blitz. People ask me how I keep doing this, and that is the one question that generally leaves me at a loss for words. Perhaps the most common question I'm asked is "is this ver- sion of Crafty some dumbed-down version of what you play on ICC or what you use at a computer chess event?" The answer is a resounding *NO*. The current version is *exactly* what is running on ICC under this version number. Note that a new version can, on occasion, introduce weaknesses or out- right bugs that were not present in previous gold" versions. As a result, you should be careful to back up your "favorite" before trying the latest and greatest. If you aren't satisfied with the new version, you can then "go back." If you are looking for the strongest playing computer chess program available, you should likely look to Genius, Rebel, Mchess Pro, and the other commercial entries. There you will find strong opponents with polished interfaces that have been tested in a systematic and careful way. If you are looking for a program that plays good chess, has a rea- sonable set of features for you to use, is available in source form, and one where the author welcomes feedback, code or suggestions, then you are at the right place. I welcome comments and suggestions, and also feedback from ideas you try yourself that seem to work. Crafty is a state-of-the-art computer chess program, and uses all of the search algorithms you have probably read about, negascout search, killer/history move ordering, SEE (Static Exchange Evaluation) quiescence move ordering and pruning, hash (transposition/refutation) tables as well as evaluation caches, selective extensions, recursive null-move search, and a host of other features that have been used and are still being used in most computer chess programs. If it's not in Crafty, either it is on the "to do" list, or it has been tried, found wanting, and discarded. Chess Knowledge is growing, and suggestions (or even better, real code) are welcome. This is the best place to con- tribute your ideas, because knowledge can be used to sup- plant search and make it play better. The evaluation is probably the easiest place to start studying Crafty because of the comments and simplicity of using bitmaps, *once* you get "into" them. My purpose for doing this is an exercise in computer chess efficiency. I can't begin to count the number of people I know that started from scratch to write a chess program. Even larger is the group that started from scratch, and gave up before finishing, because of the basic size of the pro- ject. Crafty offers everyone a very clean starting point, if you are fascinated by the bitmap chess board implementation (as I am). The search and quiescence code is reasonably straightforward, as is the evaluation, It offers a great starting point, so that if you are inter- ested in trying a new search extension, you can be testing tomorrow, rather than next year, because you start with a fully functional chess engine that is not a "toy" applica- tion, but is a functional and "dangerous" chess player. It offers a rapid start, although you can certainly replace it piece by piece until it is "yours" if you want. It also offers a fairly complete set of commands and an interface for a GUI as well as support for chess server play, so that testing and debugging your new ideas is greatly simplified. If you'd like more information, please check out the read.me document and the crafty.FAQ that are distributed with Crafty. These contain recent news and specific instructions for commonly asked questions, like "where can I obtain tablebase files and how do I use them?" How to play a game. ------------------- When you execute Crafty, you will immediately be greeted by the prompt string "white(1): " and Crafty will wait for com- mands. This prompt means it is white on move, and we are at move #1 for white. You can first use any of the commands from the alphabetic command listing below to tailor the game to your liking (time control, hash table size, book random- ness, etc.) and then you have two choices. If you want to play white, just enter your move, and Crafty will take it from there and make a move in response. You will then be prompted by "white(2):" and it is your move again. If you would prefer to play black, just enter either "move" or "go" at the prompt and crafty will move for that side rather than accepting a move from you. After it makes its move for white, you will then see the prompt "black(1): " indicating it is now time for blacks first move. You can enter a move, or you can once again enter "move" or "go" and Crafty will again move for the current side, change sides, and prompt you for what to do next. If you find yourself continually using a set of commands to configure crafty to play as you want, you can put these com- mands in a startup file called .craftyrc (Unix) or crafty.rc (DOS/Windows). The format for this file is just like you would type the commands at the keyboard, with the require- ment that the last line of the file must be "exit" on a line by itself. Using this, each time you start Crafty, it will first execute the commands from this file before it prompts you for input. While Crafty is running, you can control what it displays, but here's a couple of samples to explain what it is saying and why: depth time score variation (1) book moves {d4, c3, Nc3, d3, b3, c4, g3, b4, Be2, Bb5} book 0.0s 70% d4 White(3): d4 time used: 0.01 This is the normal output for those cases where Crafty is in book. The book moves line gives the set of book moves that made the first selection cut (see the book selection expla- nation given later), followed by the move actually played, in this case d4. If Crafty is out of book, then the output looks somewhat different as given below: depth time score variation (1) 4-> 0.81 2.09 dxe4 Bxe4 Rad8 Qf2 Qb5 5 1.37 2.41 dxe4 Bxe4 Ne5 Qf4 Bxe4+ Qxe4 f5 5-> 1.88 2.41 dxe4 Bxe4 Ne5 Qf4 Bxe4+ Qxe4 f5 6 7.38 -- dxe4 6 11.90 1.97 dxe4 Bxe4 Rab8 Qf2 Qc7 Nc5 Qe5 6 12.92 ++ Ne5 6 13.71 2.23 Ne5 Qg2 Ng6 h5 Nh4 Qg4 6-> 15.59 2.23 Ne5 Qg2 Ng6 h5 Nh4 Qg4 time: 15.60 cpu:99% mat:1 n:246565 nps:15927 ext-> checks:4706 recaps:1336 pawns:0 1rep:301 nodes full:45951 quiescence:200614 evals:104657 endgame tablebase-> probes done: 0 successful: 0 Let's take this stuff one line at a time. Lines that have something like 4-> in the depth column are printed when that iteration (depth) is completely finished. The time and score columns should be obvious as to their meaning as is the PV, the sequence of moves that led to this score. the line that has -- in the score column means that when we started depth 6, dxe4 turned out to be worse than we thought (notice score dropped from 2.411 last search to 1.972 for this move this search.) To resolve this, Crafty lowers the lower search bound (alpha) and re-searches the move to find the score. The line with ++ means that this move (Ne5) is better than the best move so far, so Crafty raises the upper search bound (beta) and re-searches this move to find the new score. the first line of statistics gives the total time taken for this search, the cpu percentage which should stay at 98-100% unless your machine is heavily loaded or unless Crafty is in an endgame that is having lots of contact with endgame databases. If this drops below 98%, it means that Crafty is not getting full CPU usage and will be playing weaker than normal. The mat:1 is simply the true material score, since Crafty's positional scores are often larger than a pawn. Alphabetic Listing of Commands ------------------------------ 1. alarm on|off This command is used to control Crafty's "beep" after it makes a move. Turning this off will make Crafty "quiet" when it plays, but also makes it easy to miss a move if you are using crafty to play in a tournament. This is primarily designed to make Crafty tolerable during late night matches. 2. analyze This command puts crafty into analyze mode. In this mode, Crafty starts computing for whichever side is on move, and it continues computing and showing its analysis until a move is entered. This move is made, Crafty changes sides, and starts thinking and printing analysis all over, but for the other side now. This command is useful to play through a game, because you get instant feedback when you try a move. If you want to try a different move from the one you just entered, use the "back" command to back up one move, or use "back <n>" to back up <n> moves. Note that one move is a single move for the last player, not a move for both sides. To unmake the most recent 2 moves (one for black, one for white) use "back 2". 3. annotate <filename> <colors> <moves> <margin> <time> This command is used to annotate (make comments in) a game that has already been played. <filename> is the name of the file that has the game moves stored in it. This should typically be a PGN-compatible file, although Crafty can read nearly any file with chess moves. <colors> indicates which side Crafty will annotate. The valid choices are w, b, and wb for white only, black only, and both, respectively. Crafty will search and produce results for the indicated color only, making moves for the other side silently as they are read in. <moves> indicates the moves that should be annotated. If this is a single integer, annotation starts at this move number (for the color given above) and proceeds for the rest of the game. If a range is given, as (20-33), then only moves 20-33 inclusive are annotated. To annotate the com- plete game, you can use 1-999. <margin> gives a score "window" that controls whether Crafty will produce comments (see below). The larger this number this number, the fewer annotations Crafty will produce. A negative number will result in an annotation for every move selected. <time> indicates the time limit for each search. Since each move selected requires two searches, you can take the number of moves, double this number and multiply by <time> to determine how long the annotation process will take. This time is in seconds. How it works. Suppose you use the command "annotate game1 w 1-999 1.000 30" This asks Crafty to read the file "game1", and annotate the white moves for the entire game. The mar- gin is 1 pawn and the search time limit is 30 seconds. The output for the annotate command is found in <filename>.can, in this case this is game1.can. Crafty first searches the move actually played in the game to determine the score for it. Crafty then searches the same position, but tries all legal moves. If the score for the best move found in this search is greater than the score for the move actually played plus the margin, then a comment is added to the output file. This output file is quite short, with all the game moves (plus any PGN tags in the original, for identification purposes) plus the brief com- ments. An annotation looks like this: {real_value (depth:best_value PV moves)} real_value is the score for the move actually played. depth is the depth Crafty searched to produce the best_value and PV for what it thinks is the best sequence of moves for both sides. If you set <margin> to 1.000, you are asking Crafty to only annotate moves that either lost a pawn or more, or moves that failed to win a pawn or more. If you set <mar- gin> to .300, you are asking for annotations for any move that makes the score drop about 1/3 of a pawn below the value for the best move Crafty found. If you have other moves you would like to see analyzed dur- ing this annotate process, at the point where the move can be played, insert it into the PGN file as an analysis com- ment, surrounded by () or {} characters. Crafty will pro- duce analysis for this move as well. If more than one move appears inside a single set of delimiters, only the first will be analyzed. To force Crafty to analyze more than one move, enter them like this: (move1) (move2) as though they were two separate comments. 4. ANSI on|off This command is used to control whether or not Crafty attempts to display its move in reverse video or not. For PC's, Linux, and most Unix boxes, this works fine. Should you find yourself playing crafty via a dumb terminal, this might hose the terminal and interfere with your ability to see or input moves. If moves are not displayed in reverse video, it's probably wise to turn this off to avoid hanging the terminal you are using. 5. black|white This command simply toggles the side on move. if it is white to move, and you enter white, nothing happens. If it is white to move and you enter black, then it becomes blacks turn to move immediately from the same position. Used only infrequently. 6. book (see the book explanation near the end of this doc- ument for a full explanation of this command and its many options.) Note that there are special commands available (*only* on the command line, *not* in the crafty.rc/.craftyrc files) to direct crafty to specific directories for the book files (bookpath=/a/b/c), the table- base files (tbpath=/i/j/k) and the log files (log- path=/x/y/z). Note that these commands can *only* be used on the command line, because they must be executed before the engine is initialized. Putting them in the crafty.rc/.craftyrc file will produce error messages without affecting how the files are opened. 7. clock <ctime> <otime> This command is primarily intended for use when Crafty is playing in a tournament, such as the WMCCC or WCCC events. If the operator is some- what slow in entering moves, or forgets to stop the clock after making a move for Crafty, the chess clock for the game will drift from the values that Crafty maintains internally. <ctime> is the time (in minutes or hh:mm format) crafty has left until the next time control, and <otime> is the oppo- nent's remaining clock time. This command can be used at any time, but will only affect the time per move *after* crafty makes the current move and starts to think about what the opponent might do next. 8. display this command is used to display the game board. This board is displayed using the ICS style #1 type of ASCII display, with white always at the bottom of the screen, black at the top. Very unusable to play a game with, but good to verify a position after it has been set up. This command is also used to display the various piece/square tables, by typing "display <piece>" where <piece> is replaced by pawn, knight, bishop, rook, queen or king. The board is oriented in the same way as the display board with a one-to-one correspondence between the squares. Perhaps useful for curiosity, but not for anything else. These values can not be modified by the user. The final version of this command is used to control what kind of output you will see when crafty runs. Currently the following options are available. display time: this will make Crafty display the amount of time each side takes after making a move. display changes: this will make Crafty display the PV each time it changes during the search, including when a move fails high or becomes a new best move. display variation: this will make Crafty display the PV at the end of each iteration, but it will only show the best PV for the entire iteration, not all of the changes. display stats: this enables basic search statistics output including time, nodes and so forth. display extstats: this enables extended search stats including the hashing statistics, search extension statistics and so forth. display movenum: causes all PV output to have move num- bers embedded in them to make the PV possibly easier to read. This causes the PV to look like this: 12. ... Nxe4 13. Bxe4 h6 rather than simply Nxe4 Bxe4 h6. This is very helpful when playing on a server and whispering or kibitzing analysis. It will also be useful when crafty is run from within a database program as the move numbers will sync up with the actual game. display moves: will display each root move as it is searched, along with updating the search time at the bottom of the screen, so you can see what move is cur- rently being analyzed. display general: will display general information mes- sages whenever Crafty wants to tell you something (ie "clearing hash tables" or other such things like "Mate in n moves." If you put a "no" in front of any of these options, that will disable that particular type of output. 9. draw offers Crafty a draw. It generally will look at the value returned by the last search, and compare it with the value returned by an internal function DrawScore(). If the search value is not above this result, then Crafty will accept the draw. If the search value is above the theoreti- cal value for a draw, Crafty will decline the draw. Note that crafty will offer draws based on internal analysis. When it offers a draw, you can respond with "draw" although the game does not really end until you exit Crafty. 10. echo <text> This command is normally used inside a command file that you are going to use to "feed" crafty some positions for analysis or whatever. Since crafty depends on the operating system to echo commands as they are typed, commands read in from a file are "invisible." This gives you the ability to insert commands into such a file so that crafty displays a message on the screen to give you an idea of where it is in processing the file. 11. edit This command has been "cloned" from GnuChess to provide an interface with Xboard. After entering the "edit" command, you are in "edit.white" mode, where any piece/square combination you enter will add the indicated white piece on the given square. Piece/squares are entered as "qa3", or "bc4" for example. This puts a white queen on a3 and a white bishop on c4. Once all white pieces are entered, typing a "c" changes to "edit.black" mode where piece/square combinations now place black pieces. Typing a "." character exits edit mode. To clear the board ini- tially, you use the "#" character. Here's a sample to set up the original starting position, after white has played 1. e4, but no other moves have been played. edit # ra1 nb1 bc1 qd1 ke1 bf1 ng1 rh1 pa2 pb2 pc2 pd2 pe4 pf2 pg2 ph2 c ra8 nb8 bc8 qd8 ke8 bf8 ng8 rh8 pa7 pb7 pc7 pd7 pe7 pf7 pg7 ph7 . Note that input is free form, so piece/squares can be entered one per line or all on one line. Ditto for the #, c, and . special characters. Note also that there is no way to enter castling status here. It is far better to use the "setboard" command which uses a FEN-like syntax and allows you to set both castling and enpassant status. 12. end|quit These commands are used to terminate crafty. Note that you can resume a game later without having to replay the moves, by starting Crafty using the "crafty c" command. It will immediately read in the moves for the last game, although you will have to set the time controls and clock time remaining yourself. 13. flag on|off This command is used to force crafty to end a game where the opponent runs out of time with win- board/xboard (on) or to ignore this (off) if desired. 14. force [move] This command is used to force Crafty to play a move that is different from the one chosen and played by the tree search. If [move] is given, and it is a legal move, Crafty will retract its last move and make this move instead. It does not change the side on move, but does change the position of course. If [move] is not given, Crafty will prompt you for a move to make. 15. help This command displays multiple pages of one-line help, one command per line. If a line ends with [help], then you can use help followed by the specific command to get detailed help. 16. history This command displays the history in a verti- cal column with one move for white and one per black per line. There are other ways to display the current game moves and also to save them in files that are explained later. 17. hash=x and hashp=x These commands are used to adjust the size of the hash tables in Crafty. hash modifies the size of the transposition/refutation table, while hashp mod- ifies the size of the pawn structure/king safety hash table. The sizes may be entered as one of the following two types of values: nnnK where nnn is an integer indicating how many Kbytes Crafty should use for this hash table; nnnM where nnn is an integer indicating how many Mbytes Crafty should use. The transposition/Refutation table is the most critical of the two, because it directly affects search efficiency, par- ticularly in the endgame. For this reason this should be maximized. The most effective size for this hash table is 3/4 of your available memory. If you don't know how to fig- ure this out, but know that you have 16 megs for example, they you can say hash=16M and crafty will round that down to 12M, which is 3/4 of a power of two size. If you study the sizes that are possible, you will find 3M, 6M, 12M, 24M, 48M, and so forth. Anything up to, but not including, the next size will be rounded down to the next lower size. hashp should be set to approximately 1/2 of what is left. For example, the P6 Crafty runs on when playing on ICC often uses hash=48M and hashp=8M. The only thing to watch for is that if you make this too large, particularly under windows, performance will suffer badly because of paging I/O over- head. When Crafty is searching in a normal (non-book, non- endgame database) position, the disk light should *not* be on, indicating lots of I/O. There is no danger in making this table too large, although you have to watch out because if Crafty barely fits in mem- ory, doing something else on the machine can cause Crafty to be swapped out completely or partially, depending on the operating system you are using. If you are going to use the machine for anything else while Crafty is running, it is better to "pretend" that the machine only has 1/2 of the memory it actually does when computing the size of the hash tables you want to use. 18. import <filename> [clear] This command is used to import any sort of learning data that Crafty supports, which currently includes book learning data and position learning data. This command reads the appropriate <filename> and imports that learned data, just as though Crafty had learned it by playing the games. The [clear] option, if specified, caused all old learned results to be cleared before the import operation, otherwise the imported data is simply added to what is already present. 19. input <filename> This command is used to redirect the console input I/O stream from the keyboard to a file. Crafty will then read commands from this file, rather than from the keyboard, and execute them just as though they were typed in. Such a command file *must* be terminated by an "exit" command (no quotes) as the last command in the file. This reverts the input stream back to the keyboard, and prompts you for another command or move. This command might be used to configure crafty for a spe- cific time control, by putting the appropriate time control commands in the file, or to customize the hash table sizes as needed. 20. info This command is used to display information about Crafty and the current game. Such things as the time con- trol, the time left on the clocks and other information is shown. 21. learn n controls the learning facilities in crafty. Currently this is a 3-bit boolean switch, bit 1 (001) con- trols book learning, bit 2 (010) controls position learning, and bit 3 (100) controls result learning. learn=0 disables all learning, learn=1 enables book learning only, learn=2 enables position learning only, and learn=4 enables result learning. Add the values together to turn on more than one type of learning (default=7 to enable everything). 22. level <m> <t> <inc> This command was taken directly from GnuChess so that the Xboard/WinBoard interface would interface with Crafty. There are other better ways to set the time, but this one is well-known. The three parameters are <m> (number of moves in the game) <t> initial time on the clock. After <m> moves are made, this amount of time is added to the clock again. <inc> is the Fischer-Clock incre- ment that is added back to each clock after a move is made. It may be zero for a non-increment game. Examples: level 0 5 0 (ICS 5 0 game) level 0 5 3 (ICS 5 3 game) level 0 15 30 (ICS 15 30 game) 23. list GM|IM|C|AK|S +name [+name ...] -name [-name ...] This command is used to maintain the internal "lists" Crafty uses to auto-tune itself when playing on a chess server. There are three lists, GM, IM and C. If Crafty's opponent is in any of these lists, Crafty adjusts internal controls that affect how/when it resigns or offers draws, and how randomly it will choose moves from the opening book. For example, Crafty resigns much sooner against a GM, because it assumes he knows how to win a rook-up ending, regardless of how much time is left. By the same token, when playing against computers, Crafty will always assume that a draw is 0.000, so that it doesn't wreck its position trying to avoid repeating a position. The AK list will automatically kibitz scores/PV's if the opponent is in this list. The S list will turn on special scoring for opponents in this list. The only current member is "mercilous". The syntax +name1 +name2 simply adds these players to the specified list. To remove a name, use -name1 -name2. You can use one command per name to remove or add, or you can use one command to add and remove multiple names. 24. log off|on|<n> This command is used to disable log- ging. The default is log on, which causes crafty to produce a new log.nnn file for each game played. If you are running Crafty on a server, you might use log off, which disables creating these files as well as the game.nnn files used to restart a game after you exit crafty and come back later. If you use the form "log n" crafty will simply display the last n lines of the log on the screen. If you use "log n file" crafty will copy the last n lines of the log to "file" which could be your hard drive, or a floppy. Note that if you run with log off, you will be unable to find out what Crafty was thinking about since there is no other record of the game. You will always see a game.001 because as crafty plays a game, this contains all the real moves played so far so that you can back up if needed. you will also see a log.001 file, but it will be empty. 25. mode tournament|normal This command is primarily used to put Crafty into "tournament" mode, which is intended for use when Crafty is playing in computer chess events. It accomplishes two things: (1) makes all draws return a score of 0.000, and (2) makes crafty issue a message after each move showing the internal chess clock time, and requesting that that operator check and adjust as needed using the "clock" command. This primarily makes Crafty comply with computer chess rules that say the operator can't do anything not specifically requested by the program. 26. mt=n This command is used to set the number of threads to use on a machine with more than one processor. For opti- mal performance, "n" should be set to the number of proces- sors you have, although using fewer will reduce the load on your machine. For this command to work, Crafty must have been compiled with SMP defined. When compiled with SMP enabled, mt=0 effectively disables the SMP code completely. 27. name <name> This command is an ICS-play specific com- mand. Xboard/WinBoard uses this to inform Crafty of the opponent's name. Crafty uses the name, and looks it up in its GM/IM/C lists, and if found, adjusts itself accordingly. This is not used by the PGN code and this will not cause the players <name> to show up in the PGN tag section. 28. new This command wipes everything out and starts a brand new game. It closes the old log-file and game-file, and opens the next sequential numbered file. It also resets the game to the beginning and prepares to start a brand new game. This was added for Xboard, but it turns out that Xboard does not use this, rather it starts Crafty fresh for each new game by first terminating the old copy then start- ing a new one. Not nearly as efficient as using "new" but likely safer it a program can't be sure of resetting every- thing back to the initial state. 29. noise <n> This command sets the "noise" level in Crafty. Basically, until <n> nodes have been searched, crafty will be silent and not display analysis. This is useful in two ways. First, in end-games, 20+ ply searches are not uncommon, and the search analysis for the first few plies arrives so quickly that it is distracting. Second, when observing games (new interface only) on ICS servers, this can be used to avoid having Crafty generate too many analysis kibitzes. A value of 100000 will basi- cally shut off any output for the first second or so (on a P6/200). Similarly, 1000000 will eliminate any output for about the first 10 seconds. When watching and kibitzing games like the World Championship games on ICC, I generally use 5000000, which is almost one minute of silence so that the first PV it kibitzes is a pretty deep search. noise 0 will cause *all* analysis to be displayed, which on a fast machine causes no problems. On a slower machine, or over a slow phone connection, this might cause a big commu- nication backlog. The default is roughly one second on a P6/200 (100000) but can be modified by this command. 30. operator <n> Another command intended for use when Crafty is playing in a tournament, operated by a human. This tells crafty to "hide" <n> minutes of time and not use them. This time is basically allocated to the operator to make up for the time it takes to type in moves and/or cor- rect mistakes. At the WMCCC events, the normal value we use is 5. Playing on a server, this is not needed, as it is not needed if you are playing Crafty yourself. 31. perf This command is primarily used in optimizing Crafty, or to test the speed of the move generator and Make- Move()/UnMakeMove() on different platforms. It produces two results, the moves it can generate per second, and the moves is can generate and make/unmake per second. While this is not a perfect performance indicator, it does give an "approximation" for how fast Crafty might run. In general, the higher the numbers, the better the program will play, although machines are certainly different. It's not uncom- mon to find a machine that searches slower than another, but has a higher "perf" value. 32. perft <depth> This command is generally used to con- firm that the move generator and bitmap operators are work- ing properly. It simply takes the current position, and generates/makes/unmakes moves and counts them. Many pro- grams use this from a "standard" position to make sure that their move generator does not miss generating odd moves like enpassant/promotions and also to confirm that the make/unmake code correctly updates the board so that the totals remain constant across different machines and pro- grams, since there is no alpha/beta or evaluation things done. if <depth> is greater than 5 or 6, it will take a *long* time, since this is basically a minimax tree traver- sal that will visit *every* node within the <depth> search horizon. 33. pgn <tag> <value> This command is used to set the usual PGN tags to meaningful values. The recognized tags are Event, Site, Round, Date, White, WhiteElo, Black, Black- Elo, and Result, and the tags *are* case sensitive. The <value> can be any valid input and blanks and special characters are allowed. Note that the date is clearly spec- ified in the PGN standard and must be yyyy.mm.dd with no variance. Valid results are 1-0 (white won), 0-1 (black won), 1/2-1/2 (drawn) and * (unknown). Some examples: pgn Event 14th World MicroComputer Chess Championship pgn Date 1996.10.8 pgn Site Jakarta, Indonesia pgn Round 1 pgn White Crafty pgn WhiteElo 2400 pgn Black assassin pgn BlackElo 2400 pgn Result 1-0 Setting these values will result in a proper PGN file when using the savegame command. Note that if you use the "read" command to input a PGN game, these values will be extracted from that game if they are given. 34. ponder off|on|<move> This command serves two purposes. First, it can be used to disable (off) or enable (on) think- ing on the opponent's time (or pondering as it is called in many programs including Crafty.) Turning it off will weaken Crafty since it will not use any machine time while waiting on the opponent to move. It is sometimes useful, however, when playing Crafty against another computer and the machines are not equal. If crafty is on a faster machine, and you attempt to adjust for this by giving the opponent more time than Crafty, it doesn't work quite as expected, because while the opponent is thinking, so is Crafty, which lets it use the extra opponent time in an unexpected way. In such a case, it's best to stop pondering in both pro- grams. If <move> is given, it directs Crafty to use that <move> to ponder, rather than the one from the previous search. Most commonly this is used to set the right move to ponder after Crafty has been stopped and then restarted, assuming that it is the opponent's turn to move when this happens. Other- wise, it is probably better to not try to influence things, although if you are watching and suddenly wonder "what would Crafty do if the opponent plays move 'X'?", you can answer this by simply typing "ponder X" and then watching the anal- ysis. You should reset the correct ponder move after you do this of course. 35. savegame <filename> This command is used to save the current game in a PGN-compliant file with the PGN tags included. Note that the default TAG values might not be what you want if you do not either use the pgn command to set them or else input a valid PGN file with the tags already filled in. Be aware that this command doesn't check the filename for legality since anything goes in UNIX. In DOS, you might produce a bad filename with either too many characters, too many periods, or whatever, so be careful with the name you choose. Note also that this file will be overwritten if it already exists, so be sure to choose a name that is not the name of a file that has something you consider important in it. 36. savepos <filename> This command writes a single line into <filename> in FEN-like notation. This lets you save a position, and then come back later to re-examine it. You would use the "in <filename>" command to input this file and set the position up. 37. reset <n> This command lets you back up in the current game to any move of your choice. reset <n> backs up the game to move <n> with the same side on move. If you want to first change the side to move, use the white/black command, then use the reset command to back up to the right move. Note that you can also go forward as well, just so there are moves in the current game history. 38. resign <n> This command sets the resign threshold. When running on ICC I typically use "resign 9" which will make crafty resign roughly five moves after the score drops below -9.000. For IM's I change this to 6, and for GM's I often use 3, so that it will resign quicker and not drag a lost game out unnecessarily. 39. read/reada [<filename>] This command will read input, and extract the chess moves and make them to set up the position at the end of the game. It first resets the chess board to the initial position (read command only) and then extracts the PGN tags (if present) from the front of the input. The rest of the input is parsed for chess moves (comments and similar things are culled automatically) and the moves are made and added to the game history. Once this is done, you can back up, go forward, or play from any point in the game. If you specify a <filename> everything is read from the file, otherwise it is read from the console key- board. The reada command reads moves, but appends them to the cur- rent game history/ position rather than resetting to the initial chess position. This lets you read in a game, then use reada to manually add some more moves to see the result- ing position. 40. search <move> This command allows you to specify one particular move for the side on move, and then when you tell Crafty to search this position, this is the only move that will be searched. This is used internally by the annotate command, but can be used to investigate one specific move. If the move is not the best move, a normal search won't show you why it is bad, but this will. It is also quite a bit faster since the other moves in the position are not searched at all. 41. settc <moves> <ctime> <otime> This command is primar- ily used in tournaments, and is an error-recovery command. If the machine crashes and corrupts the game history file, frequently the operator will have to simply set the position using the setboard command, and then use the settc command to restore the time control values. <moves> is moves until the next time control (from Crafty's perspective, be careful and don't look at the opponent's moves to time control by accident.) <ctime> is minutes left on Crafty's clock, <otime> is minutes left on the opponent's clock. 42. setboard <FEN input> This command is used to set a chess position up for analysis and is the preferred way to do this, rather than using the gnu EDIT interface. It uses a classic Forsythe-like notation to encode the position and also has provisions for castling status and enpassant cap- ture status. the standard piece codes p,n,b,r,q,k are used to denote the type of piece on a square, upper/lower case are used to indicate the color of the piece (uppercase=white pieces, lowercase=black pieces). the pieces are entered from the classic chess diagram's ori- entation of a8 being the upper-left-hand corner of the board, and this square is entered first, followed by the remainder of the 8th rank left to right. To indicate empty squares, use a number between 1 and 8 to indicate how many adjacent squares are empty. use a / to terminate each rank after all of the pieces for that rank have been entered. Note that you do not have to account for all 8 squares on a given rank, although many test suites do this for clarity. the following input will setup the board position that given below: k2r/ppp////Q/5PPP/7K/ B this assumes that k represents a white king and -q repre- sents a black queen. -k * * -r * * * * -p -p -p * * * * * * * * * * * * * * * * * * * * * * * * * * * * * q * * * * * * * * * * * * p p p * * * * * * * k * the field after the final "/" should be either b or w to indicate which side is "on move." after this side-to-move field any of the following characters can appear to indicate the following: KQ: white can castle king-side/queen- side/both; kq: same for black; a1-h8: indicates the square occupied by a pawn that can be captured enpassant. 43. score This command simply gives the positional score for the current position. This score is from whites per- spective, so a + score is good for white, a - score is good for black. Crafty also breaks the score down into major categories (from Evaluate()) to indicate things like pawn structure, piece evaluation, passed pawns, development, and so forth. Note that some of Crafty's evaluation is asymmet- ric, so that if you simply change sides with the white/black command and then enter "score" again, you may get a differ- ent value. This is *not* a bug. :) 44. sd <n> This command lets you specify a specific search depth limit that Crafty can not exceed. It still pays attention to the clock, however, so often you will use the st <n> command (below) in conjunction with this if the search is going to take an extended amount of time. <n> is the depth (in plies or 1/2 moves) that the search must reach. Note that if Crafty is pondering, it still honors this limit and will stop a ponder search after this depth has been completed as well. This is *not* the way to make Crafty play weaker, although this will be covered in a later section of this document. 45. st <n> This command lets you specify a specific search time limit for Crafty. Again, this is not the preferred way to set a time per move, because this limit is absolute and Crafty will never go over this limit, even if it sees that it is losing or getting mated. Setting the time control with the usual "time" or "level" command is *much* better. <time> is given in seconds, although it may also be entered as mm:ss if preferred. 46. show <category> This command forces Crafty to display additional information about certain actions it takes. Cur- rently the only <category> is "book" which will make crafty display information about all the book moves it found in the database. More is given about this information in the BOOK section later in this file. 47. test <filename> [n] This command will run a suite of positions (the file must be in "Crafty" format as explained below) and produce a summary of how many it got right, wrong, etc. It uses the time per move you set with the (typically) st <n> command. The optional paramenter [n] is the "early exit" counter. If Crafty finds, and holds the solution move for n iterations, it will terminate the search. I use this to make a win at chess run take < 15 minutes, even though the time per position is set to 1 minute, by setting n to 2. After two correct iterations, Crafty goes on to the next problem. For absolutely correct results, this is not advisable as it could obviously change its mind later on, but for performance analysis, this saves a lot of time. The test suite contains the following lines: (this is a sample from my test suite for Win At Chess.) title wac299 setboard 1n2rr2/1pk3pp/pNn2p2/2N1p3/8/6P1/PP2PPKP/2RR4 w solution Nca4 title wac300 setboard b2b1r1k/3R1ppp/4qP2/4p1PQ/4P3/5B2/4N1K1/8 w solution g6 end The title command simply displays this message in the log file so you can look at the output and figure out which position it goes with. This is optional, but useful. The setboard command sets the position as explained before. The solution command gives the set of solution moves (one or more moves that are separated by blanks) and/or a set of "anti-solution" moves (moves that must not be played to count the position as correct.) "anti-solution" moves are simply followed by a "?" character, for example: solution Bxa7? The solution command supplies a set of key moves, and then starts the search. If, after the search terminates, one of the key solution moves was chosen (or none of the anti-solu- tion moves were chosen) the position is counted as correct. The final line should be "end" although end-of-file or EOF will also be detected in this case. 48. time CPU|elapsed|<values> This command controls whether the program uses CPU time or wall-clock time for timing. for tournament play, it is safer to use wall-clock timing, for testing it may be more consistent to use CPU timing if the machine is used for other things concurrently with the tests being run. time is also used to set the basic search timing controls. the general form of the command is as follows: time nmoves/ntime/[nmoves/ntime]/[increment] nmoves/ntime represents a traditional first time control when nmoves is an integer representing the number of moves and ntime is the total time allowed for these moves. the [optional] nmoves/ntime is a traditional secondary time con- trol. increment is a feature related to ICS play and emu- lates the Fischer clock where <increment> is added to the time left after each move is made. as an alternative, nmoves can be "sd" which represents a sudden death time control of the remainder of the game played in ntime. the optional secondary time control can be a sudden-death time control, as in the following example: time 60/30/sd/30 this sets 60 moves in 30 minutes, then game in 30 additional minutes. an increment can be added if desired. One final example is the following: time sd/15 which is a simple game/15 setting. This command can also be used to perform the same function as the "level" command. For example, to set up a classic ICS 2 12 game, the follow- ing would would work: time sd/2/12 49. trace <n> This command is used to make crafty display the tree as it searches a position. Due to the incredible speed at which this program can search, however, this is less than useful since it can swamp any known display driver and make things scroll impossibly fast. Also note that this command usually is disabled, because Crafty is generally compiled with the -DFAST flag, which removes the trace output code from the search to make things slightly faster. You will have to recompile, without the -DFAST, if you want to use this. It's utility is limited, except for debugging, anyway. 50. usage <n> is simply a way to modify Crafty's time usage to fit your tastes. You can "suggest" a time limit with any of the options discussed previously, but if you use anything other than the "st" command, Crafty will do its best to use time as you suggest, but it also anticipates that it will save some time by pondering, etc., and will therefore be more aggressive at trying to use time. if <n> is a positive integer, it is taken as a percentage and crafty will compute the time limit it thinks is appropriate for the current clock settings, then increase this limit by this percentage (50 would make it take 1.5 times longer than normal.) -50 would make it take 1/2 the time it would normally take. Crafty adjusts the usage internally based on time left, opponent's time left, how quickly or slowly the opponent is moving, etc. Further modifying things with this is danger- ous, but possible. 51. whisper/kibitz <n> These commands are used to control what Crafty will whisper or kibitz on a chess server. The options are (1) only whispers or kibitzes mate announce- ments; (2) adds time, score, depth to the previous option, but no PV or moves. (3) adds the PV. (4) adds book move information to the output. The remaining two options gener- ate a lot of output and should be used with caution. (5) displays the PV after each iteration completes. I use this when using my custom interface to let Crafty observe/comment on games in progress on ICC. Noise can be used to prevent shallow searches from generating output and keeping "noise" down on the games being watched. (6) basically will whis- per/kibitz nearly everything you see on the console from a search, each PV when it changes, fail highs and fail lows, etc. A significant amount of output that should be care- fully weighed before turning it "loose." 52. Xboard This command turns on Xboard/WinBoard compati- bility mode, and makes Crafty behave somewhat like GnuChess. This is designed to be used *only* when Crafty is interfac- ing with Xboard/WinBoard. Crafty will not work with these two GUIs without this option, and really won't work very well with this option if it is not connected to one of them. Opening Book Setup and Usage ---------------------------- Crafty uses two pre-compiled opening books, called "book.bin" and "books.bin". The file book.bin is usually build from a large text file containing PGN games, often taken from collections of GM games. Building book.bin is a simple exercise and requires nothing other than the raw input file you are going to use. Generally this will be either medium.zip or the set of four files large[1-4].zip, all of which are stored on the ftp machine ftp.cis.uab.edu/pub/hyatt/. To create the file book.bin, you need a PGN game collection that is a *real* PGN-compliant file. Supposing this file is called "large.pgn" you would use the following command: book create large.pgn <m> [n] The only thing you have to supply is <m>, a number indicat- ing how many moves from each game are to be stored in the book.bin database. I typically use 60, which stores the first 60 moves from each game. Increasing this number slightly increases the probability that Crafty will stay in book longer, but it also increases the probability that it will follow a game too far, so that it begins to reach posi- tions where the move actually played might not be the best move, letting it fall into a bad hole. Increasing this also increases the size of the database as well. You can decrease the size of the book, and also reduce the number of ugly moves by specifying "n", which says that unless a move is played in at least N games, the move is discarded. This will substantially decrease the size of the book.bin file, and also eliminate single game moves that often have significant errors or blunders. After creating book.bin, you need to create books.bin. This is a small version of book.bin, which is intended to give you more control over the moves/openings Crafty will play. This is usually built from the file start.pgn on the ftp machine, but you can modify this file to suit your taste easily. To build books.bin, you use the following command: books create start.pgn 60 Again, 60 is what I use, but none of my start.pgn lines go anywhere near that many moves. The main point here is that in start.pgn, you can append a "!" to any move you want, and when it is Crafty's turn to move for that color, it will play from the set of moves with "!" if there are any, ignor- ing the rest of the book moves. If you only want it to play 1. e4 as white, you would just enter the short game: [Crafty only plays 1. e4] 1. e4! and you are finished!. You can enter as many as you want. If on the other hand there is a move you don't want Crafty to play, then follow that move with a "?" and it will never play it. Moves in books.bin that are not flagged with ! or ? don't have any influence on Crafty's choice at all. Here's how the files are used. When searching a position, Crafty first enumerates the set of moves it can find in the opening database. It then does the same for the books.bin database, and performs a "merge" operation to combine the ? and ! flags... The purpose of the books.bin file is to give you a small database that you can easily modify, rebuild, and repeat this process over and over. Since it takes a fraction of a second to completely rebuild this file, it is very easy to modify this to control what Crafty will play, without having to rebuild the large database. One important characteristic of the PGN input is the Result tag must be specified in most of the lines, because Crafty counts wins, losses and draws for each book move and uses these counts with some of the book selection options given below. How the flags are used. The ! and ? flags should only appear in the small books.bin file, although there is no reason why they can not appear in the large file as well. For this discussion, it doesn't matter since Crafty takes the moves from both files and "merges" the flags/etc into one entry for each move. Quite simply, if any book legal book move has a ! flag, then Crafty will only play moves from the set of moves which all have the ! flag. If a move has a ? flag, then that move is immediately removed from the set of possible book moves. If the only legal book move has a ? flag, it will not be played as a book move and Crafty will simply pretend that it found no book moves and will execute a normal tree search. Pretty simple. How does Crafty choose book moves? Crafty's book selection algorithm depends on two user- defined values that can be set at any time during a game: book random <n> book width <w> The selection algorithm first finds the set of legal book moves as above. This set will either be all ! moves, or will have no ! moves in it. This set is then sorted based on the setting of book random. Here's the options: book random 0. This is a special case for book selection. Crafty simply takes the set of book moves, and searches only these moves using a normal alpha/beta search, but with a shorter than usual time limit. It then plays the move that produces the best search value. This has one serious disad- vantage in that there is no randomness to this at all. It will always play the same move in the same position, unless the evaluation is modified, or the time per move is differ- ent enough to let the search find a different move from the book move set. book random 1. This enables a random form of book move selection, but you have a lot of control over how moves are randomly chosen. The moves are ordered, based on 4 parame- ters: frequency of play, win/lose ratio, static evaluation and learned results. Normally these are factored into the value used to sort the moves, based on default settings that you can modify by using the command "bookw option N" "option" should be "freq", "ratio", "eval" and "learn". N should be a number between 0 and 1. Crafty finds the min and max values for each of the 4 param- eters, and then maps this into the range 0-1000 for each parameter. Each parameter is multiplied by the correspond- ing "weight" you have assigned, and this is used as a value to sort the moves from low to high. Once Crafty has sorted the moves as given above, it next excludes any book moves which have 0 wins. This culls the odd lines where a player chose a bad line and lost quickly. With zero wins, it will never be chosen, although Crafty will happily follow it from the other side. :) This is not anywhere near perfect, however, because an opening could have 1 win and 19 losses and that still would stay in the list. If a move has a learned value of > 100, this move is ele- vated in priority to that of a ! move, since it appears to win material instantly. If a value is < -100, it is given a ? since it appears to be a lemon. After this, the setting for "book width <w>" is used to keep the first <w> moves in the list, after the above culling has been completed. The smaller you make <w> the less random- ness you get, but the chance of Crafty popping out a really bizarre book move gets smaller as well. Once this has been done, crafty simply uses the "sort value" for each move to compute a total for all moves. It then generates a random number between 1 and this limit, and chooses the move that this probability distribution matches. This will certainly evolve over time as new ideas are devel- oped. For my play on ICC, I use book random 1, and book width 5 normally, although for titled players this is reduced to book width 3. For computers, I reduce this further to 2, to try to play reasonable openings and cull the gambits and things that don't work out. How does book learning work and how can I share learned results? 1. *all* of crafty's "learned knowledge" is in the book.bin file. It keeps the learned value and learned count right in the book file for speed. You can't modify it, although "show book" will make crafty display all the book stuff before it makes a move. 2. the book.lrn file has two purposes: (a) to serve as a log for your prying eyes, so you can see what it's learned, against whom, and what the score was that got its attention in the first place. The values on the end of each book line, inside the {} characters are as follows: {value, depth, rating_difference} value is the value of the "key" search that comes from the first 10 moves out of book. it's in millipawns, and + is good - is bad. depth is the depth the search reached at this "key" position, the deeper the search, the more the value is "trusted." rat- ing_difference is crafty's rating - opponent's rating a neg- ative value means pay more attention to the score since the opponent is better than crafty, a positive value means to take the score with a grain of salt, because the opponent was weaker than Crafty. You can delete this file at any time, and it has no effect on learning. As I mentioned, the learning takes place in book.bin... this is mainly for you to peek at if you are interested. However, this is the "portable learning data file" also, and can be given to others to import into their crafty, where it will affect the opening book just like their crafty had played the openings and got the same scores. There are two ways to use such "lrn" files: 1. "import <filename>" will read <filename> and import the knowledge therein into your book.bin. Since I use the same learning code as is used when playing games, this informa- tion also gets appended to *your* book.lrn file as well, so that your book.lrn always reflects *everything* your program has learned, so long as you don't ever remove this file. It would be a mistake to use this command on your own book.lrn file, because the things would get counted twice, which might or might not be a good thing. 2. "import <filename> clear" will read <filename) and import the knowledge as above, but first clears *all* learned results from book.bin. you will want to do this if you import my book.lrn, *and*, you have contributed to my book.lrn data by sending me yours. I'll take care of elimi- nating duplicates if you screw up in what you send me, but once you send me something, you run the risk of getting it "back again" later. This is going to be a problem until everyone gets used to sharing something that is rather "vapid" like this "learned info" is... Other than that, we are now "open for business"... when the urge strikes you, email me your .lrn file, I'll keep a large master here and update it on occasion. Probably the best thing to do is to send me your .lrn and at the same *instant* delete yours. This will capture anything learned *after* you send me the file, but you'll get it all right back with the next version of book.lrn that I distribute. after getting this new book.lrn back, here's what you should do: 1. rename your old book.lrn to something else. I'll call it "book.lrn.old" here. 2. copy my blearn.dat to your machine, but *do not* put it in the directory with your book.bin and books.bin file because it will get confusing very quickly if you do. put it somewhere else, because you are going to remove it quickly anyway. I'll call it new.lrn for this example. 3. import new.lrn clear import book.lrn.old and you are ready to rumble again. The first command clears the learned values, sucks in my new learn file and updates everything. the second command re-learns everything you've learned since you sent me the last book.lrn file. After doing this your book.lrn will have my .lrn stuff, plus your old.lrn stuff, just waiting to be sent to me again... If this is confusing, I can probably add an automatic com- mand to do all of this by renaming book.lrn, etc. Hopefully this is not too error-prone for the time being anyway... What is this new Position Learning I've heard about? Crafty now has a "permanent" hash table that is kept from game to game. A position gets into this "hash file" when Crafty executes a search and the search value is signifi- cantly lower than the last search value. When this happens, Crafty stores the current information for this position in the permanent hash file, which can hold up to 65536 positions. Once it fills up, the positions are replaced on a FIFO basic always keeping the most recent 64K entries. Each time crafty starts a search, the positions/scores from this file are stuffed into the normal transposition table, and used during the search just like any other table entry. Here's how it helps: In a game that was played, the follow- ing moves and scores were found by crafty (playing white): 1. Ng5 (+.277) h6 2. Nh7 (+.321) Kg8 3. Qh5 (+.133) Qg7 4. Ng5 (-2.122) hxg5 So, the knight got trapped at h7, and at move 4 crafty dis- covered that this is gross and "learns" this result/position. We play the exact same game again: except that two things can happen here. It might be that Ng7 is the *only* square the knight can move to here, which means this whole thing is forced. the first search would find: 1. Ng5 (-2.122) if the search can reach 8 plies deep, which happens even in 5 second games. It's learned that Ng5 is bad. It stores *this* position in the permanent hash file also, and the next time you try this same trap, it will dis- cover 4-5 moves earlier that if the knight gets to g5 it is in trouble. Each game will diverge from the first game 3-4 moves earlier. Simple and effective. 2. Ng5 might not be forced, and if not, it knows Ng5 loses a piece for a pawn, so it will promptly play something else, which is exactly what is desired. This is implemented with two (count 'em, two) files. One file "position.bin" is a binary file that contains the hash table entries, and it right at one megabyte in size, *max*. (16 bytes per hash entry X 65536 entries = exactly one meg, but I have 8 extra bytes for the FIFO queue implementation and to see how many entries are currently in the file if it is not full. The second file is "position.lrn" and is, you guessed it, a file that can be shared with others, just like book.lrn. It contains all information needed to reconstruct the position, the score, the depth, etc. and also included the pgn tags for who was what color and when the game was played... This data can be imported with the new "import" command (the old book learn <filename> is no longer around) which will import either book.lrn type data or position.lrn type data and can tell them apart without your having to do anything. The <clear> option is still there, should you want to use it, and simply removes the position.lrn and position.bin files before starting the import process for position learn- ing. This can be turned off, if you like, by checking out the "learn" command, which gives you the ability to turn off book learning (as it presently works), position learning, and the next book learning stage which will add to the book in addition to learning which book lines are good and bad. What is this new "result" learning? Result learning works just like normal book learning, except that if Crafty is checkmated or resigns, it will step back through the book line to find the last point where it had more than one move to choose from. It will flag the move it chose as "never play again". This handles the case where the first ten non-book moves produce reasonable scores, but the position is one that Crafty simply can't handle very well. If it loses such a game, it will still vary the next time this opening is played, as otherwise it would possibly repeat the same open- ing, and would certainly repeat the remainder of the game. All three learning modes are turned on by default, although any of them can be disabled with the appropriate command option to "learn".