Phalanx is a chess playing program Copyright (c) 1997, 1998 Dusan Dobes LICENSE AND WARRANTY - Phalanx is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. - Phalanx is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. - You should have received a copy of the GNU General Public License along with Phalanx; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. WHERE TO GET PHALANX ftp://sunsite.unc.edu/pub/Linux/games/strategy/ (and mirrors) ftp://ftp.math.muni.cz/pub/math/people/Dobes/ COMPILING, PORTABILITY Compiling is simple, at least under Linux. Just type `make'. Phalanx is developed under GNU C, GNU Debugger, and GNU Make. It's probably possible to compile it on many different platforms, but today i have no oportunity to try it on any other platform than Linux and HP-UX. If your system does not support GNU exensions (e.g. long options), remove '-DGNUFUN' from DEFINES in makefile. If you have incompatible 'make', try this: $ cat *.c > allphalanx.c; cc -O allphalanx.c -o phalanx INTERFACE, COMMAND LINE OPTIONS Phalanx is xboard compatible. Running with xboard: 'xboard -fcp phalanx'. Note that permanent brain (pondering) is off by default. Newer versions of xboard set it on with the 'hard' command. If this does not work, try 'xboard -fcp "phalanx -p+"' or (for <4.0.0 versions of xboard) change your initString (see Xboard documentation for details). It's better to stop permanent brain in both programs, when playing Phalanx against another program on a machine with one CPU. It's also possible to run phalanx without xboard. Do "phalanx -h" to get a list of command line options. One important command of phalanx's ASCII interface is "help". MORE ABOUT INTERFACE I'm trying to write an interface that fits following three requirements: - Xboard compatibility. For best results, get the latest version of Xboard. - shell-like interface that allows running commands in a batch. It's very useful for testing. Example: look into the file test.fin. It's a set of chess problems and solutions. You can simply send this file to Phalanx's stdin: $ phalanx -c+ -o- -b- -f10 < test.fin | tee result ( Where: -c+ .... use cpu time -o- .... don't use polling input -b- .... no opening book -f10 ... fixed time 10 seconds per move ) Watch how it works. - Acceptable ASCII interface. OPENING BOOK From version VI, there are two book files - primary (pbook.phalanx), and secondary (sbook.phalanx). You can specify book directories via command line (-P, -S) or use environment variables PHALANXPBOOKDIR and PHALANXSBOOKDIR. Otherwise Phalanx tries to find its book files in current directory (./book.phalanx, ./sbook.phalanx) and finally in compiled-in directory (/usr/local/lib/phalanx). You can change the compiled-in directory in makefile. - pbook.phalanx is 'hand'-written, text book. One line per position, sorted. This time, it's bigger than really needed, because it was the only book file till version V. The size will be smaller and the line format might change to EPD+SAN in future. - sbook.phalanx is binary book, generated from large PGN files. Six bytes per move (4 hash key, 2 move). You can generate your own sbook.phalanx with 'phalanx bcreate', like this: $ ./phalanx bcreate < manyGMgames.pgn or: $ ./phalanx bcreate 1250000 < manyGMgames.pgn ( where 1250000 is internal buffer size in cells. One cell takes 12 bytes. Bigger is better, only if it's too big a part of the buffer is unused. E.g. 1250000 is enough to parse Crafty's 'medium' book source - 29MB. ) A position is first searched in pbook.phalanx. Only if it's not found there, sbook.phalanx is searched. INSIDE THE MACHINE Phalanx uses (traditional) 10x12 board implementation. There are three often used board implementations: "8x8" (GNU Chess), "bitboard" (Crafty), and "10x12" (Nimzo, Phalanx). In short, "10x12" is easy to implement and the code and basic data structures are small ( == fast on PC). The engine uses many well known techniques: PVS (principal variation search), transposition/killer table, static-eval cache, history killers, SEE (static exchange evaluator), null move pruning, forward pruning, internal iterative deepening, chess-specific extensions. AUTHOR Dusan Dobes, dobes@math.muni.cz HISTORY The rest of this file is history of Phalanx. I First version to play a legitimate game, it finally knows all rules. 19970304 I spent a lot of time on tuning transposition table code and extensions. The program scores 78% at large Reinfeld's test set, 10 s per move, on 486+/150. II Two killer heuristics added: well known history killers (modified) 199704?? and `reaction' killers (the killer is connected to the previous enemy move). The tree search is faster, especially at `quiet' positions. Hashtable presearch. Modified hashentry replacement strategy. Better evaluation function, it now knows more about passed pawns, the endgame play is much stronger. Fixed bug at 7-th row pawn push extension routine. Faster output - using sprintf() to prepare the output and then only one printf. New command line options: -t, -T to set the hashtable size. III Permanent brain (pondering). King safety evaluation. Hung pieces 19970529 static evaluation. Null move pruning. Forward pruning. Better time heuristics - forced moves are played quickly. New cmd-line options: -f, -x, -p, -s. IV New option -c to determine whether to use cpu or real time. The 19970721 internal timing resolution changed to 1/100 of a second. Xboard compatible editing position. Removed en-passant capture from quiescence search. Changes in static-eval function. Piece list implemented - speedup is between 0 and 20%; more in endgame. Pinned pieces static evaluation. Better evaluation of weak pawns. Trapped bishop and knight evaluation. Bugfix at extending check evasions. Bugfix: development bonus was computed but not added to total evaluation. Output change: '!' means turn, '!!' means value out of window. V Mostly interface changes, no big improvement in playing strength. 19970803 Xboard compatibility fixes: 'post' is no more switch, new command 'remove'. Fixed command 'level': 'level 0 5 0' (five minutes per game) should work, also increment (ICS) levels ('level 0 2 12'). Increment can be given at command line. New option -o (polling input) - when running tests, phalanx needs -o-. New feature of autotesting: all incorrect results are written into file 'notfound.fin'. Small output changes for better compatibility with xboard 3.6.2. Eliminated some bad turns in evaluation. Better king safety evaluation - counting safe checks available. VI Fixed small efficiency bug in evaluate.c. Improved time heuristics 19970915 for increment (ICS) levels. Optimized hashing - about 5% overall speedup. Fixed bug in ptime(). User is now allowed to continue play even if the position is drawn by 3-rep., material, or 50 moves rule. Fixed bug - Draw requests are now always ignored, not always accepted :-). Xboard-compatible 'Illegal move' message. Binary opening book, created from PGN by bcreate. This distribution is bigger than any previous because it contains a small example of binary book ('sbook.phalanx', 174kB, 29634 moves). SAN input accepted. Static evaluation now better understands middlegame positions without castling. Added pre-computed tables into static evaluation -> about 5% speed improvement. 'Show thinking' mode now shows also a list of book moves if there's a book entry. I have played a match with previous version (64 games, 2 minutes, increment 12 seconds, on a 486+/150, via xboard, no pondering), new version wins 38.5-25.5. VII Courtesy of Pavel Janik ml., new command 'fen'. Bugfix in command 19971022 line parser, 'phalanx 0 2 12' now works. Better time controls: added hard time limit to avoid being flagged. Pondering bugfix: Phalanx was pondering O-O, but opponent played O-O-O; the move check was incorrect and Phalanx thought that O-O was played; this resulted in 'Illegal move' message few moves later. More pondering safety: the move to be pondered is now checked for legality, before this fix it was simply taken from PV (if present), but PV is not always 100% correct. More PV safety: search cannot be interrupted during the first iteration, the abort is delayed until the first iteration is finished. New options: -r , -b <+/-> to set opening book on/off. New commands hard/easy to set pondering on/off. Optimized do_move(): 3% speedup in test positions. Search optimization: null move is not played if the value in hash table entry is too low. Output bugfix: output is now readable even at long time searches. SEE (Static Exchange Evaluator) and more pruning in quiescence search. RoboFICS compatible commands 'white' and 'black'. Routine for evaluating pawn endgames. New extension trick that helps in some horizon-effect type positions, it's based on measuring difference between current score and null move result; if current score is much better, the side to move must be under threat and the line is extended, similar trick is also in gnuchess. VIII Fixed bug in search(): eliminated useless re-searches -> about 3% 19971103 speed improvement. Noise level is now in centiseconds, not in nodes. Improved horizon-effect extensions. endgame.c: new endgame knowledge, mostly for endgames with minor pieces and pawns: knight and bishop mating, knight+knight (draw), minor vs. minor (draw), minor vs. pawn (draw, but still needs some work, sometimes a pawn wins against a knight), onepawn() as a special case of pawns(), bad bishop (bishop + rook pawn), basics for R+P vs. R, bishops with opposite colors (this is often drawish ending). New penalty for moving castling-side pawns in middlegame. IX Function smove() is now used in both binary book and hashing code, it 19971205 is cleaner and easier to read, the binary is smaller with this. Bugfix: Phalanx now does not ponder move that leads into a terminal position (checkmate, stalemate), this fixes some unexpected quits (I hope all of them). Added more limits to horizon-effect extension trigger - there was so many extensions, that version VIII was actually weaker than previous versions, because of lower nominal search depth; these extensions are now used only for major threats. Static eval cache entry is now packed into 4 bytes instead of 8 -> the cache eats only 256K (512K before this). X Bugfix in static evaluation of trapped knight at [AH]7. Better 19980108 evaluation of trapped bishop ([AH]7) and knight ([AH][87]), now it's using the static exchange evaluator. Time allocation: alloc more time (+1/8) if pondering is on. Better understanding of 'trade-down' bonus - if there are no pawns, you often need a rook more to win the game, a minor piece is not enough. Shallower extensions resulting in greater average search depth. Easy levels: use new command line option -e <1...100> to select an easy level; 1 is the strongest and 100 is the easiest one, Phalanx tries to make human-like blunders. Minor changes in resigning. Clean up in pbook.phalanx, deleted over 100 positions. Killer heuristics now uses the SEE. Bugfix in endgame.c: trade bonus did not work for kings and pawns endgames. Simple learning, can be activated by -l+ option; it is off by default, because it's very experimental version. New version wins engine-engine match with version IX 23:17 (tc 2, inc 8, 486+/150, no learning, no pondering). XI Courtesy of Milan Zamazal: long options and user-friendly handling of 19980125 book files - you can now use environment variables or command line options. Bugfix in trade bonus: endgame KQ-KBPP was evaluated only about +1.10, but the stronger side is winnig here even without pawns, now it's >+3.00 and Phalanx can solve this Dufrense&Mieses study: 8/3Np3/7P/1p3P2/1k6/5K2/1b6/8/w Pf5f6. Deeper overall extensions, +10% of ply. More check evasion extensions. Wider window for 'lazy evaluation', search is now slower but stable. Minor fixes in forward and null move pruning. Zero-width search modified for root moves, actually it's no more zero-width; this eliminates some 'blind turns' (a move is evaluated as >=(Alpha+1), but the engine cannot prove it in re-search in full [Alpha,Beta] window). Minor changes in static evaluation. Bugfix in time allocation of increment levels. Changed time heuristics to use more time. XII More pruning in quiescence search: moves that have little chance to 19980301 return the value over alpha are not generated. Permanent brain is now really 'permanent', if there is no move to ponder in the PV, Phalanx uses short search to pick a move and ponders it. Bugfix: occasional zero division at very fast time controls, like 10s/game. Some puts() replaced with printf(), puts() is buggy in my gcc (2.7.2) and causes sigsegv when interrupted and called again during the interrupt. Optimized null move, this speeds up the engine. Easy levels now use nodes instead of centiseconds for measuring time, the playing strength of easy levels does not depend on cpu power and cpu load. Resigning now works with RoboFics (via 'tellics resign'). Updated FSF address in docs. XIII Lots of 'char' and 'short' replaced with 'int' -> speedup on iX86 19980316 chips (about 10% on my 486, probably more on P6). Bugfix at 'edit' command, edit was broken for positions with black to move. New command line option 'bench', 'phalanx bench' runs a 5 cpu-minutes benchmark and reports nodes per second. Added some interesting lines into the opening book. Dynamic draw score, it's set to -20 by default. New command 'rating ' to adjust the dynamic draw score, Phalanx tries to avoid draw with weaker opponents, minimal draw score is -20, maximal +20. XIV Dynamic draw score did not work for stalemate, now fixed. Major bug 19980416 fixed at resigning: if resigning was on, phalanx resigned almost any game after few moves, this was broken from previous version. Simplified computing bounds for lazy evaluation, this was too complicated and slow. Higher material limit for evaluating position as endgame. Deeper extensions, +0.1 ply. Improved move ordering at root search. Minor optimizations. More variability in opening book. Disabled scout search near leafs. Bugfix: type of Nodes changed to 'long long' (64 bits on Intel[3456]86), 32-bit integer was not long enough for >24 hour runs. Bugfix: option -P did not work, now fixed. Added startup messages that show full path of all open files. XV Internal iterative deepening. Cleaned pbook.phalanx. New "Pc2-c4" 19980614 code to encourage playing c4 (c5 as black) in closed positions where e4 (e5) is not possible. Bugfix at computing total material on the board, the variable was sometimes overwritten with unexact value. New xboard compatible commands 'bk' and 'analyze'. 'bk' shows all book moves. 'analyze' starts analysis mode. Bugfix in bcreate.c: no games on stdin caused segmentation fault. GNU extensions (long options and snprintf) are now used only if GNUFUN is defined (-DGNUFUN in makefile). New endgame knowledge: KNP vs. K is sometimes draw. Small changes in static evaluation. SIGINT is ignored in polling input mode. Time information in post lines is shown in centiseconds instead of seconds to follow current draft of xboard chess engine communication protocol. XVI Bugfix in analyze mode: there is no extra character after the search 19980630 depth number in post lines - xboard understands that time info is in centiseconds, not in seconds. Bugfix in null move pruning: the side that is trying its second move in row must have at least one legal move, this caused segmentation fault if there was none. Command 'hard' does not set pondering on in easy levels. Bugfix at parsing SAN moves, nc3 was (possibly) interpreted as Pc2-c3. Command 'level' accepts time in mm:ss form, for example 'level 0 2:30 12'. Bugfix in kings+pawns endgames - penalty for pawns on one file (doubled) worked as penalty for pawns on one row. Improved kings+pawns endgames static evaluation. New command 'xboard' sets xboard compatible mode. XVII More variability in pbook.phalanx. Better sbook.phalanx, generated 19980804 from wall.pgn. Changed (and fixed) extensions for check evasions and passed pawn pushes. Changed evaluation of passed pawns. phalanx and bcreate integrated into one binary, most of the code was common anyway; book can be created via 'phalanx bcreate' instead of just 'bcreate'. Bigger limit for count of [position,move] in bcreate code, the counter has 32 bits instead of 16. Performance bugfix in null move pruning. XVIII Bugfix in the static exchange evaluator - it let kings slide 19980906 horizontally. New styling of board in command "bd"/"d". New command in edit mode: 's' to switch side to move. Modified look of edit mode. Modifications in static evaluation: bishop pair needs mobility; queen has 'king distance' bonus only if it's on a safe square; simpler rook evaluations - smaller bonuses; forpost (outpost) pawn gets more bonus for # of pieces defending it (Aaron Nimzowitsch, "Mein System"); bigger bonus for protected or connected passed pawns. Modified threat extensions - only mate threats are extended. Bugfix in analysis mode: PV is computed (and shown) even if there is only one legal move. New feature of command 'level' - 'level N' sets level to N seconds fixed time per move. Better pbook.phalanx.