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  • Kimo - a new approach for chess engines

    Chessbase News, Germany
    April 1 2004

    Kimo - a new approach for chess engines

    01.04.2004 Traditional chess programs blindly search millions of
    postions to find good moves. A new chess program due for release this
    month breaks with the tradition. It works with chess knowledge
    derived from 20,000 master games. Tests with a late beta version show
    that in spite of some glaring defects Kimo is able to hold its own
    against the world's strongest programs. Details...


    Kimo - a new approach to chess programming
    Most chess programs available on the market today are built on the
    principle of super-fast full-width searches. They generate large
    numbers of positions, and use tiny bits of chess knowledge to
    evaluate them. This method has hoisted them to the very highest
    levels of tournament play.

    But is this "brute force" approach the only way to achieve chess
    excellence? Instead of looking at literally billions of positions
    between moves, is it not possible to insert enough chess knowledge
    into a program to make it understand the difference between
    meaningful continuations and the purely nonsensical moves that
    traditional chess programs spend 99.999% of their time examining.

    The new program Kimo, created by a team of Russian programmers
    (hailing originally from Armenia and neighboring republics), sets out
    to do exactly that. Kimo's algorithms are based not on a brute force
    search but rather on chess knowledge derived from around 20,000 high
    quality games. These have been extensively analysed by the program,
    which draws heuristic conclusions on the principles of chess: the
    value of the pieces in different positions, their strenghs and
    weaknesses, attacking and defensive motifs, etc.

    In tournament games Kimo relies to a great extent on these
    heuristics, which are applied to pattern the computer recognises on
    the chess board. It also conducts a traditional look-ahead, but the
    search is highly selective and only takes into consideration
    "promising" lines of play. According to its authors Kimo generates "a
    million times less moves" than traditional chess programs.

    It is of interest to note that former world champion Mikhail
    Botvinnik, who pioneered the concept of knowledge-based chess
    programming, directly contributed important elements that are today
    part of Kimo's chess heuristics.

    Testing Kimo
    The program Kimo 1.0 is due to appear in the European computer stores
    later this month. In the US there will be a two-month delay due to
    import restrictions caused by the massively parallel hardware requred
    to run the Russians program. The German magazine Computerschach &
    Spiele (CSS) managed to get a late beta version and run initial tests
    on it. A full report by Lars Bremer is included in the April edition
    of CSS. Bremer is an experienced editor of Europe's biggest computer
    magazine C'T and is an expert on computer games (you may want to
    download his Munstrum program).

    Traditionally chess programs that are tested by CSS must first
    absolve a rigorous test suite of chess positions in which the program
    must find certain key moves. This "Weltmeister-Test" suite (which you
    can download here) is derived exclusively from games played in world
    championship matches. This led to a first problem for the CSS
    testers. The 20,000 games used to prime Kimo's chess knowledge
    included all world championship games, and these were in fact given
    high priority in the data mining process. The result is that Kimo
    solves most of the positions in the "Weltmeister-Test" almost
    instantaneously - simply because it recognises them. This naturally
    allows us to draw few conclusions regarding playing strength of the
    program.

    In his next test Lars Bremer ran a series of informal blitz games
    against other programs, with disasterous results for Kimo. Even older
    versions of Fritz were able to beat the Russian program, despite the
    fact that Kimo usually came out of the opening with an excellent
    position. This was probably because the program has a tiny but very
    high-class openings book.

    Here is a typical position in a blitz game against its rivals:

    White has a satisfactory position in spite of (or because of) its
    advanced castle pawns. A good continuation would have been Rf3 with
    slight advantage. But Kimo somewhat recklessly sacrifices the
    exchange with 16.Qf3?, expecting to launch a decisive king-side
    attack. After stubborn defence by Fritz White simply ended up with
    material down and a lost position.

    The results of the tests on the blitz level were indicative of a
    principle shortcoming of the program: its tactical vulnerability.
    Tima and again Kimo would get promising positions, and then, based on
    its knowledge heuristics, play an over-optimistic move to ruin the
    position and lose the game. Lars Bremer estimates that Kimo will not
    be able to occupy a place amongst the top programs in the blitz
    rating lists.

    Tournament games
    At slower speeds the situation is a different one. In ten games
    against today's top programs Kimo scored exactly 50%, much to the
    astonishment of the CSS testers. The general impression was that the
    program was positionally superior to its opponents, with occasional
    tactical lapses costing it a possible victory. The individual scores
    in the test matches were 3:3 against Deep Junior 8 and 2:2 against
    Deep Fritz 8 - putting Kimo right on the top of the rating lists at
    classical time controls.

    The following game is a typical example of Kimo's positional
    abilities, which always appear when the position is devoid of
    short-term tactical tricks.

    Kimo vs Deep Fritz 8


    In closed positions with locked-up pawn structures Kimo reigns
    supreme. Here it has tied up one of the strongest programs in the
    world and masterfully manoeuvred its pieces for the final assault.
    42.Nxb7 Rxb7 43.Nxa6 won a pawn, maintained the pressure on Black's
    position and quickly won the game.

    But we have to return to the tactical weaknesses, to which Kimo is
    particularly prone in open positions. Here is an example from the
    test match against the Israeli program Deep Junior:

    Kimo vs Deep Junior 8


    Kimo is a pawn down but has initiative. But instead of playing
    32.Ng6+ and going for the sure draw Kimo 32.Rh5?? In its main line
    the program displayed 32...Qxd4 33.Rxh7+ Kxh7 34.Qxf5+ and perpetual
    check. If we look at the log files we discover that it did consider
    the killer 32...Nxd4 briefly, but evaluated the position after
    33.Ng6+ Kg8 34.Ne7+ Kf8 35.Nd5 Rxh7 as 0.84 pawns better for White.
    What Kimo overlooked -- and that is the main weakness of the
    "knowledge" method -- is that after 35...Nb3+! 36.Kc2 Na1+! White is
    going to be mated. The game ended 32...Nxd4 33.Ng6+ Kg8 34.Ne7+ Kf8
    35.Nd5 0-1.

    The following test game looked like a loss for Kimo, but the program
    simplified the position and, with the help of its unknowing opponent,
    set up the following fortress position:

    Deep Junior 8 - Kimo


    The position is a dead draw, and Kimo displays this in its main line
    (0.00). Junior, on the other hand, thinks it has a winning advantage
    (+2.65). Other programs show a similar evaluation. And this is what
    makes Kimo so exceptional: in a static analysis of the position,
    assisted by a short, highly selective search, the program has
    determined that Black has a safe draw since the white rooks are
    permently tied to the defence of the b-pawn. Such analysis is out of
    the reach of all its computer colleagues.

    Conclusions
    In summary the CSS testers come to the following conclusion:

    On analysis levels Kimo often finds incredible moves, which other top
    programs will not be able to see or understand. The openings book is
    tiny by today's standard (just 30,000 positions, compared to many
    millions for the other programs), but of such high quality that we
    have yet to see Kimo come out of book with an inferior position. In
    middlegame positions it is very reliable in finding good, solid
    moves, many of which actually seem to initiate long-term strategic
    plans. The endgame is generally played at a very high level, but
    unfortunately the manufacturers have failed to implement five and
    six-piece tablebases, which put Kimo at a distinct disadvantage when
    playing against other top programs.

    In general Kimo is a very promising step in the attempt to discard
    pure brute force and use the "knowledge" method. It's the over-all
    playing strength is quite astonishing and equal to that of the top
    programs. As an analytical tool Kimo shows constistant flashes of
    brilliance, but it can also miss important tactical points. You
    should definitely double-check Kimo analysis with Fritz, Junior or
    Shredder before you put full faith in it.

    But the biggest problem with Kimo is the running expense. The program
    will only work on a custom-built massively parallel hardware, and it
    also requires extensive care and maintenance. All of this is
    exorbitantly expensive compared to contemporary cash-and-carry PCs.
    We estimate that each game played by Kimo can run a bill of thousands
    of dollars.

    For this reason the CSS editors conclude that Kimo is not yet ready
    to compete commercially with the other engines. But it is aa very
    interesting new direction and worthy of being watched.

    http://www.chessbase.com/newsdetail.asp?newsid=1558
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