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December 2014, Version 1.1

- LMR added
- eval pruning added
- major cleanup of evaluation function
- new king attack function
- new futility pruning restrictions

September 2008


- display of book alternatives
- FIX concerning illegal book moves
- NEW: book moves can be selected by their frequency


- a couple of int functions whose returned value has not been used renamed to voids
- clearing of the search driver now done in search_run, not in time_xxx_go
- more comments


- in search procedures renamed smove m[256] to smove movelist[256];
"m" should be reserved for a single move
- move_isPseudoLegal() replaced by move_isLegal() which tests for check


- NEW: search_iterate() stops on one legal reply after searching to depth 4
- new names and location of functions move_isPseudoLegal() and move_countLegal()
- more comments in search.cpp
- separated book.h
- FIX: replies to moves excluded from the opening book ( again )

August 2008


- small internal book (in case that book file is missing)
- FIX: timing-bug


- FIX: various bugs occuring in fast time controls
- only legal moves are checked at the root
- FIX: hash memory allocation change possible
total memory = hash + hash/4(pawn hash) + 4mb(opening book, etc)
- FIX: communication bug, stealing cpu of opponent
- FIX: en passant flag is not set when no pawn can execute en-passant capture
( which helps with opening book and increases the number of transposition table cutoffs )
- change in delta pruning
- a couple of range checks added
- numerous opening book code fixes
- simplification of move parsing routine
- because of ChessWar, reintroduced badCapture() pruning in quiescence search


- NEW: program can use a TSCP-like book, exclude some moves out of it and handle transpositions
- changed time management + comments


- NEW: program can use a TSCP book and handle transpositions


- FIX: removed all compiler-warnings (more attention given to variable types)
- FIX: correct output of mate-values
- FIX: transposition-table crash fixed, when size set to 0
- FIX: ==/= bug in eval.cpp
- encapsulation of useKiller
- slight changes with futility-pruning
- created header file for transposition-table
- NEW: 4% speedup through prefetching the transpositiontable entry


-FIX in pawn shield evaluation "=" replaced by "==" (aaargh!)


- new pruning in QS (testing if a queen capture and/or promotion can improve alpha)


- NEW: evaluation hashtable (currently disabled, since lazy eval performs much better,
but might become useful after a rewrite of evaluation function)
- finding good configuration of compiler switches


- further restructuring of search routines
- NEW: aspiration search


- separating setKillers() function


- serious restructuring of root search functions (sepatating search_root and search_iterate)


-FIX: hash moves from lower depths used for sorting


- NEW: contempt() function instead of constant


- NEW: adaptative null move pruning
- FIX: loop counter for killer moves initialized as 0, not as 1 (bad Pascal habits!)
- FIX: in info_currmove() first move number is 1, not 0 (bad C habits!)
- in search() variable move_to_make instead of a loop redetecting best move
- in movegen.ccp vectors represented as constants (NE etc) not as numbers
- in movegen.cpp unnecessary int functions changed to void
- getting rid of is_futility compiler switch


- NEW: Pawn-hashtables
- NEW: fast_eval()
- because of that changes futility pruning gives some benefit, so it's enabled now
- added move_iscapt() and move_isprom() to improve readability


- NEW: function slavMistake() that discourages blocking the center
- NEW: futility pruning (currently disabled, as node savings do not offset speed loss)

July 2008


- separating com_nothing() function
- more customizable evaluation parameters


- NEW: CPW.ini stores evaluation constants
- Transposition table: The size is scaled down to the next lower power of 2
- thus replacing the slow mod operation by a quick 'and' operation when generating the tt-index
- reducing the tt-entry size from 24 to 16 bytes. (changing alignment)
- stop tt_save from overwriting an entry with the same position of a shallower depth
- com (uci-protocol): 'setoption name Hash value n' works now


- TWEAK: reducing a score jump caused by castling
- TWEAK: bringing down mobility scores and second lazy evaluation limit
- TWEAK: penalty for the lack of pawns


- TWEAK: raising piece/square scores
- TWEAK: modification of evalFianchetto()


- NEW: history heuristics
- TWEAK: doubled pawns do not count as a double king's shield
- TWEAK: expanded pawn center evaluation: support for e4 pawn also counts


- NEW: basic fianchetto evaluation
- NEW: console interface will accept only pseudo-legal moves


- NEW: killer heuristics (ugly code in need of redesign, but gains a couple of percent nodes)
- FIX: nodes per second calculation overflow problem fixed
- NEW: more human-friendly output in console mode


- NEW: console mode reacts to "st" and "sd" commands


- separating the eval.h file for function not used outside eval.cpp (better encapsulation)
- making use of 088_math.h and changing most of its functions into macros
- TWEAK: rooks on open files near the king increase tropism
- scaling of middlegame king evaluation affects also pcsq score
- creating a eval_vect struct collecting partial scores
- serious restructuring of eval.cpp
- creating printEval() function giving some insight into evaluation components
- FIX: fixed a bug with delta pruning (it does not prune promotions anymore)


- better time management
- FIX: time check done once every 1024 nodes, not in each node - massive speedup
- optimization of doubled pawn eval (a table instead of multiple ifs)


- NEW: PVS added
- FIX: a check extension also at the root (hash results from a move ago will be used more consistently)
- separated PIECE_VAL and SORT_VAL, simplifying the code and getting rid of problems with king value
- in fillSq() and clearSq() the count of pawns on a file is kept, so doubled pawns and open files are finally evaluated
- fillSq() and clearSq() don't update piece/square value for a king (this is done within eval.cpp)


- FIX: check extension bug fixed

June 2008


- FIX: leaf node hashing bug fixed
- some move sorting experiments


- repetition detection - from now on CPW becomes a chess engine (as opposite to almost-chess engine)
- FIX: solved the bug with the hash-values when time is over (tt_save only saves the hash, when time_over == false)
- FIX: solved the bug with the communication
- null move implemented

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