NEWS of GNU Chess

  Copyright (C) 2001-2013 Free Software Foundation, Inc.

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.

Version 6.0.3 (March 2013)

- Run autoreconf and configure based on autoconf 2.69 and automake 1.13
to get rid of these vulnerabilies:
  http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-4029
  http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-3386
- Update configure.ac to automake 1.13.
- If in manual mode, keep it after undo.
- Remove some unused code.

Version 6.0.2 (March 2012)

- New option --addbook to compile a book.
- Maximum file name length of EPD files extended to 127 characters.
- Book file allowed to be read only unless the BookLearn option is set.

Version 6.0.1 (August 2011)

- Allow kibitz for solve command.
- If gnuchess.ini is not found, report error before prompt.
- Fix 'book on' command.
- Fix 'book add' command.
- Insert sleep(0) in adapter thread - prevents from crash for
solveepd with st 30.
- Typo in info file: 'book.dat' replaced by 'book.bin'.
- Correct INSTALL: 'cd src' before './gnuchess'
- Remove some unused code.

Version 6.0.0 (27 April 2011)

- First official release of GNU Chess version 6!
- iq6.epd no longer included in the distribution - stored in Subversion.

Version 5.9.92 (24 April 2011)

- Implement 'book *' commands as in v5.
    (Implemented by extending the protocol messages between frontend and 
    adapter. Engine book options uncontrollable, since I am more reluctant
    to modify the protocol between adapter and engine (UCI), but it could 
    be done.)
- Implement v5 command 'hash on/off'.
    (UseTrans to be variable and driven by new option.)
- Implement v5 command 'null on/off'.
    (UCI option NullMove Pruning)
- Implement v5 command memory.
    (UCI option UseTrans)
- Implement v5 command memory N.
    (UCI option Hash)
- Remove v5 commands hashsize/hashsize N. Memory command replaces them.
- Hard mode at startup.
- Implement v5 command-line options not working in the previous version:
    --post
    --easy
    --manual
    --memory
- All pieces of text doc transformed into texinfo.
- Include v5 script gnuchessx for xboard mode.
- Implement script gnuchessu for UCI mode, similar to gnuchessx.
- Set writing to adapter.log to false by default.
- Default config so that the config file gnuchess.ini is not mandatory.

Version 5.9.91 (14 January 2011)

- Relax dependency on config file gnuchess.ini

New in gnuchess 5.9.90 (10 January 2011, first pretest version of v6.0.0)

- Fruit 2.1 engine, by Fabien Letouzy
- Polyglot 1.4 adapter, by Fabien Letouzy
- Three decoupled components: frontend, engine and adapter
- UCI mode, providing UCI interface, through -u/--uci command-line option.

New in gnuchess 5.07:

- New PGN parser handles annotated PGN when creating opening book
- Additional command line options
- gnuchessx script added

New in gnuchess 5.06:

- Added code for pondering and analysis mode
- Added white/black commands for use with icsDrone
- Command line options now follow GNU standards (./gnuchess --help)
- Some optimisations added
- Book may be stored in /usr/share/games/gnuchess/book.dat
- Program no longer starts search from scratch every move

New in gnuchess 5.05:

- Fixed a potential buffer overflow in pgn.c.
- General code cleanups, bug fixes, and probably introduction
  of new bugs, especially in pondering related code
- The opening book is now looked for in 
  /usr/lib/games/gnuchess/book.dat if it is not found in the
  working directory.
- Changes for easing compilation with MSVC
- Removed support for the Novag Universal Board. The recommended
  alternative is to use the winboard driver for this board, which
  is linked to on http://www.tim-mann.org/extensions.html

New in gnuchess 5.04:
- Bug fixes (as always)

New in gnuchess 5.03:
- Bug fixes (The infamous "illegal move" bug should be dead by now.)
- Architecture independent binary book. Yes, you may now move your
  binary book around between little and big endian, 32 and 64 bit
  machines and it should not break. 
- Build system is now automake/autoconf, should ease porting gnuchess
  to your favorite strange architecture. (Hell, what about gnuchess on
  cellphones...?)

Version 5.03

  Book handling rewritten, and other major changes collected and applied
  by Stuart Cracraft before use of CVS. Book need to be remade from PGN.

  List of Grandmasters we "trust" in generating the opening book was
  extended.

  Contributed Bug fixes - various.

  Code placed under CVS after some minor changes to 5.02.
  Opening book not placed under CVS - too large.

  Other changes managed under CVS

  Installation instructions corrected "book create" to "book add".
  Makefile modified to work with OpenBSD make.
  Use of C++ reserved words as variable names removed for ease of reuse. 
  The C Macro i386 replaced with Endianness test for portability.
  Lots of unreachable code removed to make it more readable.
  "#ifdef debug" and "#ifdef never" code removed.
  Removed problem with "space" on the end of filenames.
  Handle XBoard SIGINT gracefully (Caused Solaris Xboard problem).
  Reduced default hashtable size.
  Deleted Crafty style bad trade code as it was incorrect.

  The calculations for hung and pinned pieces were using stale
  information in the calculations. All relevant code was removed
  from the position evaluation routine. 
  
  Fixed loop bound error that allowed King to remain in check!!!

  Made input buffers consistent to stop crash on long commands.
  Correct hashtable handling of En Passant.
  Fixed EPD output when loading a game from file with Black to move.
  Fixed file handling problem extending opening book.

  Various modifications to SortMove to encourage examination of
  pushing passed pawns, centralisation, before other moves. Some
  modification have little effect, as the calling of sorting routines
  is quite complex.

  Added various EPD files for developer testing. These files cannot be
  included in the released tar file until copyright issues are resolved.

  Removed Outside passed pawn bonus from Evaluate as it was
  incorrectly in the pawn hash section.

  Removed the chess_faq.html file from the distribution, as this
  belongs on the GNU web site.

Version 5.02

  Various bug fixes.

Version 5.01

  Sun Mar  4 11:02:52 EST 2001 - book/book.*
    Stuart Cracraft <cracraftt@gnu.org>
    Expanded opening book

  Sun Dec 12 11:42:10 EST 1999 - src/version.c
    Patrick Gundlach <gundlach@irb.cs.uni-dortmund.de>
    fflush stdout in Xboard startup (i.e. "Chess" herald)

Version 5.00 *** RELEASE ***		(September 30, 1999 - cracraft)

o Found that after first ^C interrupt to running program a second one would
  exit it. Added a new signal (..) call in EndSearch. Okay now.

o Structure the tree (doc, book, src, etc.)

o Rename the tree from gnuchess5.0 to chess-5.00

o Revise version.h.

o Revised copywrite.

o Revised COPYING (update FSF address).

o Default to post mode (statistics) if not xboard.

Version 5.00j
     - integrated 1.21k from Kong.
     - added 
	traditional anti-computer locked pawn structure penalty
	traditional anti-computer stonewall pawn structure penalty
	crafty's eight pawns penalty
	old cobalt's ahopen traditional anti-computer edge-of-board attack
	center pawns
	shortened time until queen penalty (4 moves instead of 8)
     EICS 5/31/99
	Games:          83
	Ave.opp:        1882
	Percent:        77
	Result:         63W + 4D + 16L = 77 %
	Rating:         2093
     FICS 6/15/99
 	Games:          125
	Ave.opp:        1766
	Percent:        81
	Result:         100W + 10D + 15L = 81 %
	Rating:         2017

Version 5.00i
     - use GNU 4.0 eval instead. toss out evaluation.
     - Win-at-Chess test: 229/300 at 5 seconds per move. 10,949,825 nodes
	1507 seconds
     - Add Queen+Piece threat extension from Kong.
     - WAC: 235/300 at 5 seconds per move. 9,656,161 nodes. 1525 seconds.
     - Add the whole GNU 4.0 style calling sequence in Evaluate (lazy,
       single lone king, etc.)
     - WAC: 213/300 at 5 seconds per move, 17,911,670 nodes. 1437 seconds.
     - FICS result:
	Games:          34
	Ave.opp:        1836
	Percent:        85
	Result:         28W + 4D + 2L = 85 %
	Rating:         2132

Version 5.00h
     - book.c: when in XBOARD mode, the book needs to be quiet without status.
     - eval.c: some formatting
     - Win-at-Chess test: 219/300 at 5 seconds per move. 11,864,883 nodes.
			  1441.7 seconds (out of 1500 permitted).
     - eval.c: penalize knight on rim even more.
               up undevelopment penalty.

Version 5.00g
     - Add Crafty-style bad-trade code for bad piece exchange penalty.

Version 5.00f
     - Kong contributed rotated bitboards move generator.
       It tests 21% faster than the old move generator,
       yet overall program speed is about 8% slower based
       on testing.
     - Added ROOKTRAPPED code for rook trapped by king.

Version 5.00f
     - BUGFIX: Kong provided a fix to prevent segmentation faults in
       certain rare positions:
		6Q1/8/8/4K3/8/8/p7/1k1 w - - bm 1; id 1;
     - based on analysis of 7 lost games last night it was
       noted that 6 of these were in positions where the program
       played other than double king-pawn or double queen-pawn
       instead opting for non-classical openings, so...
       fix to always play double-pawn as long as the evaluation resolves
       to that order of moves once book has been scored.
       this is done by having the program choose from between the 
       top 2 moves for white's first move (excluding Nf3, but including
       e4 and d4) and only the top 1 move for black's first move
       (excluding non-kp/qp replies to KP/QP by white). For odd
       openings like Reti or Nc3, fairly good moves are picked with
       the above algorithm, that may be preferable to just having
       only kp/kp or qp/qp for this algorithm).
     - BUGFIX: fix problem that resulted in friendly king not being
       penalized enough for being far from enemy passed pawns.
     - FEATURE: Add DistMap[m][n] array. This array has all
       bits turned on that are n squares away from the m square where
       m is A1..H8. Aids in rapid diagnosis of distances.
     - FEATURE: Add penalty for every enemy pawn within 3 squares
       of the friendly king in the opening and middlegame: KINGNEARENEMYPAWN.
     - FEATURE: Add penalty for no friendly minors or queen within
       3 squares of king in opening or middlegame: KINGNOSUPPORT.
	Games: 		27
	Ave.opp:	1631
	Percent:	96
	Result:		26W + 0D + 1L = 96 %
	Rating:		2132

Version 5.00e (beginning of March)
     - try increasing pawncover values -- no good.
     - try diminishing underattack values -- seems good.
     - add pawn majority/minority calculation
     - add in better connected passed pawn evaluator
     - double penalty for open files adjacent to or on king's file if 
       enemy queen present.
	Games: 		91
	Ave.opp:	1763
	Percent:	87
	Result:		79W + 2D + 10L = 87 %
	Rating:		2085

Version 5.00d (late February)
     - cleaned up version prior to all the mods to get rating back.
     - one night result:
	Games: 		29
	Ave.opp:	1616
	Percent:	89
	Result:		25W + 2D + 2L = 89 %
	Rating:		1967
     - fix up PGN save-to-file routine. Was putting black in result.
     - ScoreDev returns only if fully developed.
     - Diminish connected passed pawn penalty.
	Games: 		104
	Ave.opp:	1797
	Percent:	77
	Result:		80W + 2D + 22L = 77 %
	Rating:		2008

Version 5.00b (late January)
     search.c - Razoring.  This applies at depth == 3.  If we are more
	      than a Q behind and there is no extension, then reduce 
	      the depth by 1. Extended futility pruning.  At depth == 2, 
	      if we are more than 600 points behind and there is no 
	      extension, then we only look at checking moves & captures 
	      which bring the material score back to alpha. Everything 
	      else is pruned away.  This is an extension of the basic
	      futility pruning which applies at depth == 1.
     cmd.c  - modify so that all games go to game.nnn and the
	      log of their searches go to log.nnn where the two
	      nnn's match.
     version.c - split off VERSION/etc info into version.h
     Makefile  - make version.c depend on version.h
     pgn.c     - have PGNSaveGame record player's names based on "name" command
     common.h  - adjust knight and bishop values
     iterate.c - was not taking up to 2 x nominal time per move when in
		 bad situations. fixed.
     book.c    - for random choice amongst top N moves of preferred book
		 now sorts all moves by stored book score and picks
		 randomly amongst N based. Previous algorithm was flawed.
     eval.c - add penalties for attacks against ones king in
            - add OPENGAME heuristic (1/4 pawn reward for positions
	      in which root position either side has more than 6 pawns
	      and in the leaf position both sides have <= 6
	      (idea due to Larry Kaufman and Don Dailey of Socrates)
	    - lots of work on development scoring.
     - Win-at-Chess test: 233/300 at 5 seconds per move. 14,940,780 nodes.
     - Rating went to FICS 2050 with all the positional changes on 1/31/99.
     - make king attacks per piece to reward multiple attacks to
       same square by multiple pieces
     - anti-stonewall
     - credit protectors in front of king and penalize attackers.
     - penalize repeat pawn moves before development complete.
     - rating maintained at FICS 2049.

Version 5.00a (13 Dec 98)

  - integrated with WinBoard 4.0 / Xboard
  - post/nopost (show iterative deepening)
  - time controls (level, fischer, sudden-death, time, otim, etc.)
  - works properly with FICS (Free Internet Chess Server)
  - added opening book capability.
  - futility pruning according to Kong.
  - weak back rank handling for kings
  - canned attacks against computer's king (via opening A/H file)
  - penalize early minor piece repeat moves.
  - wingpawn advance before castling penalty.
  - Win-at-Chess test: 233/300 at 5 seconds per move. 14,977,757 nodes.
  - Convert it to properly run on a standard Unix system, not just PC's.
  - Make it work with "configure".
  - Distribute to beta-testers
  -  eval.c - PawnSq[], make penalty for d2/e2/d7/e7 pawns
	      KingSq, KnightSq, PawnSq improved
     eval.h - PINNED* worsened
            - BISHOP_PAIR from 40 to 25. beta tester input.
  -  iterate.c - disable Hyatt more-time-after-book algorithm
		 disable Chua's dont-start-every-new-iteration
  - this version made a 115 point rating jump (to FICS 2030).

****************** BEGIN GNU 5 (Stuart Cracraft) ********************

Version 1.19 (18 Jul 98)
	a. Found problems when PV not updated when best >= beta; changed this
	   in both Quiesce() and Search().
	b. A ValidateBoard() function.
	c. Bug fix in SwapOff().  In Evaluate(), position with KNN with no 
	   pawns wasn't being scored as 0; done.
	d. More accurate & faster hung piece evaluation.
	e. We skip null search when MATERIAL+ValueP <= beta instead of alpha.
	   This makes more sense as we are only interested in beta.  Also if
	   the hash table returns an upper bound, the score < beta, so forget
	   about doing the null test.  This both gives about 6% reduction in
	   nodes searched.
	f. In Search(), when doing TTGet, g0 is destroyed even though we use it
	   in the null test later.  This is fixed.  Passed pawns made less
	   valuable; increased CONNECTEDPP from 450 to 650 to compensate.
	g. One-reply extensions should be checked before probing the hash table
	   otherwise, such a probe will take place at a lesser depth than it 
	   should.  The algorithm to prune if no faster mate is found is 
	   also brought forward to before the hash probe.
	h. When all root-moves fail low, it is still a good idea to try the
	   best move found at the last iteration first.
	i. Sometimes pawn-to-7th rank extensions wasn't being carried out.
           This is fixed; also these extensions are only done at the leaf only.
	   If a root move is a recapture, it is extended as well.
	j. Bonus/penalties for rook behind/in front of passed pawn.  For ending
	   don't give bonus for rook on open files as rook behind passed pawns
	   are stronger.
	k. SwapOff() wasn't handling promotion moves at all; this is now fixed.
	   Some of the sort algorithm has to be changed to take into account
	   the update to SwapOff.  Also minor bug fix to AddXrayPiece().
	l. Penalize side where a pawn base is under attack by opponent's pawn.
	m. At SearchRoot() we don't need to do any extensions.  For recapture
	   extensions, we only extend if it is capture of equal or more 
	   material so as to follow sacrifices (e.g QxP+ KxQ etc). 
	n. Bonus for pawn on c6/f6 if opponent king is in the appropriate 
	   corner.
	o. Extension for useless interposing moves.  Limit recapture extensions
	   to below Idepth+2.
	p. For PV's we no longer back it up from the root.  Now the whole
	   PV is taken from the hash table except for the first move.  This
	   is a much cleaner way of managing it, saving code in search.  
	   Otherwise, the PV that is return isn't always correct and its 
	   really very difficult to fix.
	q. There were some bugs with HashKey calculation in move.c, init.c
	   and hash.c.  These have been fixed.  The idea is that for ALL  
	   positions in a game, the HashKey must be equal to the HashKey
	   calculated if the positions are epd-loaded.  Got rid of CptrCnt[]
	   array; I no longer use it for capture extensions.
	r. King position is now stored in the variable board; we no longer
	   need to run leadz (board.b[side][king]) anymore, which takes place
	   in quite a number of places!
	s. An AttackXTo() routine which generates a bitboard of all pieces
	   of side which attack a square.  This includes x-rays.  Bug in
	   GenCheckEscapes() whereby a pawn capturing a checking piece is
	   not checked for promotion.  When Idepth <= 3, we don't do null
	   move.  This allows us to catch some mates in 2 which would 
	   otherwise be pruned away by the null move.
	t. Added in threat extension code.  A mate at any depth is better
	   than a non-mate score, so it will replace it in the ttable.
	   More "bug fixes", eg. sometimes null moves terminate the PV, 
	   hopefully this is all fixed in this release.
	u. A TTGetPV to pull the PV from the hash table.  This works better
	   than TTGet which can sometimes miss the PV due to the way the
	   hash tables are managed.
	v. Bonus for fianchetto bishops.  Minor change to TTPut() whereby
	   occasionally the same position can occupy both slots but the 2nd
	   slot has a lower draft.  The 2nd slot is wasted.  This is changed
	   so that this waste will no longer occur.

Version 1.18 (18 Mar 98)
	a. In MakeMove(), when a rook is captured, the castling flag has to be
	   updated too.  This also means that in genmove.c, when generating
	   castling moves, it is not necessary to check if the rook is on its
	   original square.  However this check hasn't been removed yet.
	b. Add "epdsave/save" command.
	c. Debug code in quiesce.c wasn't being activated; fixed.  
	d. In ttable.c, use & for calculating hashindex rather than the more
	   expensive modulo operation.  Gain a couple of percent speedup.
	   Also fix the hashsize command so that it is also a power of 2.
	   Also get rid of modulo operation everywhere else in the code.
	e. For connected pawns on 6th/7th rank only apply super bonus when
	   the enemy only has rooks.
	   When researching a fail high move & it fail low, immediately set
	   alpha to -INF and research it.  This assumes that the original move
	   did not fail high.
	f. PhasePick() was sometimes trying out the Hashmv twice resulting in
	   wasted time.  Fixed by making Hashmv[] an array.
	g. Bug in trade down code fixed.  Also modified the way worstscore
	   was calculated resulting in a significant speedup in Evaluate().
	   Fine tune ScoreB().
	h. Added a FindPins() function which returns a bitboard of all pinned
	   pieces.  This is used in eval.c for evaluating pinned pieces.
	i. Modify way in which sorting of captures was done.  This led to a
	   reduction in the quiescent search speeding things up slightly.
	j. For killers, only update them if best >= beta; this gives much
	   improved pruning.  Remove killer updates in SearchRoot().
	   Remove transposition lookup & updates in SearchRoot().  Got rid of
	   pbest in SearchRoot().
	k. In quiesce(), only update the PV if the score > alpha, not when 
	   score > best.  When a mate in N plies have been found, at the N-1
	   ply, we don't search the opponent moves; we only check to see if
	   he is mated.  Simplify SearchRoot().
	l. If the hash table returns an upperbound, then we don't want the
	   move that is returned, so set Hashmv=0.  This improves pruning.
	m. SquarePawnMask[] for pawns on 2nd rank is wrong; it is now set to
	   mask for pawns on 3rd rank as they can advance 2 square.  SwapOff()
	   used to assume that the side to move is the one moving the piece.
	   This has been changed to that SwapOff() can be used for any side.
	   Bug fixed in evaluation of trapped bishop.  Bug in GenCheckEscapes()
	   whereby an e.p. capture was allowed even if the pawn is pinned;
	   this is fixed.  A nicer and bigger board.
	n. For endings with opposite colour bishops, half the score as they
	   are mostly drawish.  Instead of penalizing weak pawns, give bonus
	   to pieces which attack weak enemy pawns.  Lots of evaluation tuning.
	   Commented out ShowThinking() resulting in faster search.  All this
	   has improved the nodes per second by 50%! Fix bug in MakeMove() 
	   whereby if a R captures another R, the castling flag for the
	   captured rook is not cleared.
	o. Updated FindPins() to include more pin situations. Introduce a 
	   variable called computer; this hold the colour that the program
	   plays.  Make a trapped bishop part of lazy evaluation as it gives a
	   high penalty.  Promotion weren't taken into account in SortRoot().
	p. A basic KPK evaluation for certain positions.  Another bug in 
	   GenCheckEscape(); a promotion move to escape check isn't taken into
	   account.  Introduced a board.pmaterial[] variable which holds the
           pieces total value for a side.  PHASE is now calculated using only
	   pieces values.  In Quiesce(), when side is in check we don't prune 
	   even if best >= beta; this is now fixed; when in check, we see if
	   we are checkmated, if not and there is a beta cut, do it saving
	   some branches.  History was updated everytime best > alpha; now it		   is updated only when best >= beta, or when a score > alpha has been
	   found.  All this gives rise to improved pruning about 2-3 %.
	q. Some fine tuning of passed pawn eval.  Add quiesce move to ttable
	   so that it can appear in the PV.

Version 1.17 (9 Feb 98)
	a. Added very elementary hanging piece evaluation.
	b. For square of the pawn, instead of adding ValueQ - ValueP, we
	   a fraction of ValueQ based on how far advance the pawn is.  This
	   is to encourage the pawn to advance and queen.  Fix a bug in 
	   IsLegalMove() whereby an en-passant was considered illegal.
	c. More accurate hanging piece evaluation.
	d. IsLegalMove() was missing out enpassant captures.  Fixed.
	e. Added a ptype[] variable to distinguish between pawn & bpawn;
	f. In Search(), initialize PVlen before checking for draws.  This fix
	   problems with illegal moves in the PV (e.g. GMG1.epd 42).
	g. Renamed Pinned() to PinnedOnKing().  A new Pinned() function will
	   be written to be more generic.  Minor change to SearchRoot(), the
	   first move is also moved within the main loop, making things tidy.
	h. Xboard support.
	i. In Search(), the first move is also moved into the main loop.  This
	   is to make the code better suited for adding threat extensions.
	   Game50 variable wasn't being properly updated; fixed.
	j. Trapped bishop at A7/H7/A2/H2.  Rook moved before castling is now
	   penalized.  Minor optimization in eval.c.  More eval tuning.
	k. Also promotion moves were not being sorted properly; this is fixed.
	l. board.ep was initialized to 0; now its -1 fixing a bug when 
	   promotion happens at A1 square (square 0).
	m. Instead of storing the whole board HashKey into the ttable, we now
	   store the top 32 bits, saving memory.  Same for Pawn table.
	n. Fix bug in backward pawn detection.  Fix bug in search whereby
	   sometimes the best move wasn't being properly set.  Fortunately,
	   this happens quite deep in the tree, so not much improvement might
	   be seen.  Change the way that scores are returned from the hash
	   table probe to improve pruning. 
	o. Trade down bonus implemented.  Recaptures extensions modified so 
	   that only recaptures of same value & square are extended.
	p. In Quiesce(), check for mates as well.
	q. Killers at ply-2 is also used for sorting.  Reduced tree size
	   slightly (2-3%).
	r. Moves in the Quiesce() search were not being recorded in the PV.
	   This is now fixed.
	s. Bug fix in evaluation of square of the pawn whereby if the opponent
	   is on the move, the pawn isn't scored properly.
	t. Phase pick is implemented.  Code seems to be working.  Also bug
	   fixes in IsLegalMove() and Evaluate().

Version 1.16 (26 Jan 98)
	a. Added a Mvboard[] array which returns the number of times a piece
	   on [sq] have moved.  Use it for penalizing early Q moves.
	b. ScoreDev() returns only development of side-to-move instead of
	   white-black.
	c. Separate Search() into a SearchRoot() which is called at ply==1
	   and Search().  Some modifications in search.
	d. Added back GenAtaks() into evaluate when doing slow evaluation.
	   Modifications in the ScoreX() routines to make use of attack tables.
	e. Fixed a bug in UnmakeNullMove whereby the board.ep variable wasn't
	   correctly restored.  
	f. Added the passed BitBoard into the pawn hash table allowing us 
	   to save the passed pawn board into the table.
	g. In evaluate, when one side has no mating material, make sure the
	   score is never > 0.
	h. Added in Square of the pawn evaluation.  Fix a bug in ScoreP whereby
	   passed pawns information was being changed.  In EvaluateDraw(),
	   fix a bug whereby 2N vs 2N wasn't a draw.
	i. Fix a bug which sometimes put an illegal move in the PV.  This
	   was happening when an EXACTSCORE was returned, but the PVlen was
	   incorrectly set.
	j. Lots of changes/tuning to eval.c.
	k. Added in an IsLegalMove() function to test if a move is legal.
	l. Added a Pinned() function to test if a piece is pinned against
	   the King. 
	m. Added a GenCheckEscape() routine to generate move when a king is
	   in check.  In SearchRoot(), there is no need to check if a move
	   is legal as all root moves are legal.  
	n. If King is in check, generate check escapes only and if there is
	   only 1 move, extend by another move.

Version 1.15 (16 Jan 1998)
	a. Convert AlgbrMove() to return char * rather than void.
	b. In the quiescent search, use SwapOff() to see if a capture is
	   futile and prune it.  Removed as it wasn't working well.
	c. Big bonus for connected passed pawns on the 6/7th rank.  Solves
	   WAC/2 easily.
	d. Bug fix and clean up of code in sort.c.  Results in improve capture
	   sorting and better pruning.  Got rid of DeepExtCnt; not used.
	e. For search extensions, limit capture to maximum of 2 and checks to
	   maximum of Idepth, the iteration depth.
	f. SwapOff() wasn't working for non-captures as pointed out by Stuart.
	   Fixed SwapOff(); appears to be okay now. Used SwapOff() in capture 
	   move ordering; seems to help a bit.
	g. In Search(), move the Quiesce() call before the ttable probe.  
	   Slight improvement in pruning and ttable stats are now much higher.
	h. Still another bug in AddXrayPiece() was fixed.  
	i. Slight change in GenMoves() to speed it up slightly.
	j. Implemented pawn hash table.  Achieves good increase in nps (25%).
	k. Added in a SquarePawnMask[] array.  This is to determine if a king
	   is able to stop a passed in a king and pawns only endgame.
	l. Material values of 100,350,350,550,1100.  Also some optimizations
	   in move.c.  PHASE modified for new material values.
	m. Implemented a two-tier transposition table.  Minimal gain in tree
	   size reduction.
	n. Only store non-captures as killers; try killers after captures
	   in sort.  This gives more than 30% reductions in nodes searched.
	   Also fix a bug in SortMoves().
	o. Only give bonus for rook on 7th rank if enemy king is on 8th rank
	   or there are enemy pawns on 7th rank.  Other bug fixes and tuning
	   in eval.
	p. Recognize and penalize backward pawns.

Version 1.14 (3 Jan 98)
	a. Fixed bug in solve.c whereby the test for a correct solution is not
	   correctly done (pointed out by Stuart).
	b. When searching for mates, eval just return MATERIAL saving time.
	c. Uses EPD format rather than FEN; also clean up ParseEPD; fen.c
	   now called epd.c
	d. io.c renamed to output.c.  Game phase is now 1-8 (opening-ending).
	e. In quiesce(), if a capture cannot bring the score near alpha,
	   don't search it, speeding things up.
	f. If we have a rootscore much worst that our previous iteration
	   rootscore, we continuing searching.  (Fix from Stuart).
	g. Got rid of nxtline, bstline way of updating the PV.  Instead use
	   the method in cheops, resulting in much cleaner code. 
	h. Got rid of savePVar[] array and all the code related to it.  
	   What its for, I can't remember.
	i. SortMoves() takes into account moves towards the centre.  Pruning
	   is slightly improved.
	j. AttackFrom() function is added.  This returns the bitboard of 
	   squares attacked by a piece.  Remove GenAtaks() and other code
	   in eval.c which required the use of attack tables.
	k. Bug in ScoreDev() whereby an early Queen move which should be 
	   penalized isn't.  Various bug fixes & tuning in eval code.
	l. PGNReadFromFile() is able to read the 1st game in a pgn file.
	m. In the null move, instead of searching with window [alpha,beta],
	   we search with [beta-1,beta].
	n. Added in a directions[][] array.  This array is used in swap.c 
	   when checking for x-ray pieces.  Added AddXrayPiece() routine
	   which is used in the static evaluator. 
	o. Got rid of foundPV variable.  It isn't really necessary.
	p. Don't flag mate score in ttable as exact score; they aren't.
	q. Change some (best >= alpha) code to (best > alpha) in Search().
	   What was I thinking of then!?

Note:  From this point on, changes within a release are labelled as a-z.  This
is also reflected in version.c

Version 1.13 (1 Jan 98)
	Got rid of history.c.  Killer is stored only if it is a beta cut.
	Fix bug in pawn eval for isolated pawns and passed pawns.  Functions
	like ScoreDev & MATERIAL now return the score for side to move instead
	of score for white.  This also fixed a bug in the null move condition
	whereby MATERIAL was only seen from white point of view when it should
	be from the side-to-move view.  Got rid of SlowEval variable speeding
	up things quite a bit.  GenAtaks() was NOT called in Evaluate(); this
	is now fixed.

Version 1.12 (27 Dec 97)
        When a mate in n-ply is found, the search will never go deeper than
        n-2 ply.  Fix some bugs in search.c.  Mate scores in hashtables are 
	now always flag as EXACTSCORE, fixing some bugs in mates.  At ply 1,
	we now don't return the hash score if it is an exact score as we
	need to search the rest of the moves.  In ttable.c, SANMove() should
	not be called as GenMoves(ply) was never called.  This affected the
	debug code.  Now algebraic moves are printed rather than SANMove for
	ttable debug code.  Fix repetition code, now gmg1.ci/42 can be solved.
	In iterate.c, foundPV should be set to false when a research is 
	being done.  A Hashmv variable is used to store the move return from
	probing the hash table.  This is use for move sorting.  

Version 1.11 (21 Nov 97)
        Nulls can be toggled on/off.  Worstscore[] is now initialized to
        -100 instead of infinity.  EvaluateDraw() is called after iterative
        deepening is over to see if the game is a draw.  New routine
        ScoreDev() to calculate development separately; "show eval" command
        will print development score.  Got rid of Developed[2] global variable.
        Some tweaking in search.c.  The decision to print '&' or '+' for a
        PV is now in ShowLine().

Version 1.10 (29 Aug 96)
	KBBK with bishops of the same colour are now recognized as draws.
	Matescore now starts from 32767 instead of 9999.  INFINITY 
	extended to 32767.  Added Ctrl-C trap so that the search will end
        instead of aborting the program.  Originally the move returned by
        a hash probe is added to the history score.  This is removed and
	the program show much improved pruning.

Version 1.9 (17 Aug 96)
	Change the way check/recapture extensions are tested; previously
	check extensions only take place at <= Idepth*2.  Now a total of
	Idepth+1 check extensions are allowed.  For recapture, a total 
	of 2 extensions are allowed.  This makes the program search deeper.
	Fix bug whereby a promotion move (e.g. d8=Q or d8Q) was considered
	illegal if the opponent tried to enter it on the command line.  
	Fixed a bug in the PVS search.

Version 1.8 (12 Aug 96)
	A lot of leaf struct variables are converted to int, making the
	program slightly faster.  Search extension for pushing pawns to
	7th rank.  The SANMove() code is now responsible for determining
	if a checking move is mate and adds the '#' sign accordingly.
	This is much cleaner.  Added passed-pawn evaluations.  Fix bug
	in eval.c where EnemyKing was wrongly initialized.  Added KingSq[]
	array to help King stay in the corner.  Added primitive development
	code; if bishops and knights are on original squares, penalize.
	Got rid of Material() and substitute a macro MATERIAL for speed.

Version 1.7 (5 Aug 96)
	A nullhashcode was added so that a null move will change the 
	HashKey (a bad bug!).  Repetition code is now working correctly.
	The enpassant and castling hash codes are now 64 bit hash values
	instead of being bits in the HashKey.  A lone king evaluator is
	added in.  This allows the program to perform elementary mates.
	Got rid of FilterIllegalMoves() in search.  Now all pseudo-legal
 	moves are tried; they are immediately rejected if it is determined
	that they are illegal.  An EvaluateDraw() routine is called early
	in the Search() and Quiesce(); if the position is a known draw 
	(e.g. not enough mating material), no searching is done.  A KBNK() 
	mating routine is added; this seems to be working fine.

Version 1.6 (2 Aug 96)
	When displaying the PV and the end is reached, see if the rest of
	the line can be found from the transposition table.  The random 
	number generator is taken from Knuth.  FilterIllegalMoves is called 
	to cull out illegal moves.  This prunes enough branches such that 
	it turns out to be a gain.  Speeded up FilterIllegalMoves().  
	Converted board.ep to short rather than using a BitBoard.  Also
	fast evaluation is done in Evaluate() rather than quiesce.  Got rid
	of epsq variable in leaf structure; it wasn't needed as a board.ep
	already exists.  A bug was introduced when the new random number
	generator was added; the top ten bits of the hashkey was being  
	corrupted; this is now fixed.  Speeded up null.c code and MakeMove()
	UnmakeMove() routines.  Got rid of piececap in leaf{} structure;
	It has been integrated in the the leaf.flag variable.  The leaf.f
	and leaf.t variable has been merged into the leaf.mv variable.

Version 1.5 (29 Jul 96)
	Mate stored in the transposition table need to be offset by (+-ply).
	Pruning via killer moves has been improved.  A new HistoryStore()
	is created for code dealing with history & killer.  InChk and 
	GenMoves() are no longer needed in quiesce().  All that work is the 
	responsibility of the full-width search.  Much improved pruning.  
	The flag structure was replaced by an unsigned long.  Got rid of the 
	ExScore variable.  Now all calls to Evaluate() will yield the exact 
	score.

Version 1.4 (19 Jul 96)
	Check for repetition in search (code currently not working).
	Added in transposition table code.  Currently there is no rehashing
	done.  The whole PV was returned to the top of the tree. 

Version 1.3 (16 Jul 96)
	For null moves, if the current material+pawn value is less than
	alpha, then we don't try the null move test.  The reason is that
	since our position is already so poor, when playing a null move,
	our score is going to be less (unless the position is zugzwang).
	So its not going to be a beta-cut neither is it likely to improve
	alpha.  This appears to reduce the nodecount.  Added a flag.ended 
	variable to the flag structure.  When this is true, the game has 
	ended and typing go will produce nothing.  

Version 1.2 (13 Jul 96)
	For sort captures, a recapture is always tried before another
	capture of the same value.  This gives slightly better pruning.
	Material for white & black is updated incrementally in make/unmake
	move.  This speeded up the program significantly.  Stalemates are 
	recognized during the search and a score of 0 is returned.

Version 1.1 (19 Feb 96)
	Added in the NULL move heuristics.  Currently the null move
	depth reduction is 2.

Version 1.0 (17 Feb 96)		(Chua Kong Sian)
	This version plays a legal game of chess.  It supports all the
	special moves (en passant, castling and promotion/underpromotion).
	It uses the standard PVS search algorithm and incorporates the
	fail-soft alpha-beta enhancement which gives tighter alpha-beta
	bounds.  All evaluations are only done at the end-points.
	Move ordering is by captures first and also history heuristics.
