Composer

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an early program for producing and solving orthodox chess problems by Scottish chess player and chess composer Norman A. Macleod. In theory the program was able of producing problems up to the size of a [|miniature] (7 men). In practice, time and storage considerations made it impractical to deal exhaustively with problems containing more than 3 or 4 men, considering following genres: directmates, directstalemate, [|helpmates], helpstalemates, [|seriesmates], seriesstalemates, serieshelpmates and serieshelpstalemates.
 * Composer**,

=Description= The method used by the program is first to find all final positions for each combination of pieces. Then the program makes all possible retro-moves. The resulting positions are sorted and duplicatons removed. Positions without a duplicate are designated "good" and those with a duplicate "bad". Retro-moves must be made from both "good" and "bad" positions, but all ancestors of "bad" positions are "bad", while only nonduplicated ancestors of "good" positions are "good". A slight variation of this procedure is needed for directmates and stalemates. Another variation was added to produce accurate multi-solution problems.

=Sample Composition= A sample composition was mentioned by László Lindner, a demonstration of Composer's abilities at the [|PCCC] (Permanent Commission of the FIDE for Chess Compositions) meeting in [|Arnhem], [|The Netherlands], 1981. The example is a [|fourfold twin], helpmate in three. The twins are all formed from the proceeding positions :

b) make e3 a white queen c) shift the white queen to b5 d) make b5 back into a white rook The solutions are exactly determined: a) 1.Kc2 Ka2 2.Kc1 Kb3 3.Kb1 Re1# a) 1.Kb4 Kb2 2.Ka4 Kc3 3.Ka3 Qa7# a) 1.Kc2 Ka2 2.Kc1 Kb3 3.Kb1 Qf1# a) 1.Ka4 Kb1 2.Ka3 Kc2 3.Ka2 Ra5#
 * [[image:http://webchess.freehostia.com/diag/chessdiag.php?fen=8/8/8/8/8/1k2R3/8/K7%20b%20-%20-&size=large&coord=yes&cap=no&stm=yes&fb=no&theme=classic&color1=E3CEAA&color2=635147&color3=000000]] ||

=Publications=
 * László Lindner (**1982**). //How the Computer Helps the Composer//. ICCA Newsletter, Vol. 5, No. 2
 * Norman A. Macleod (**1983**). //Is the Computer Going to Take Over from the Composer?// ICCA Newsletter, Vol. 6, No. 2

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