363 lines
6.8 KiB
Perl
363 lines
6.8 KiB
Perl
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% 931129 ECRC, 980312 LMU thom fruehwirth
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% 961106 Christian Holzbaur, SICStus mods
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:- use_module( library(chr)).
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handler list.
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constraints eqlist/2, lenlist/2.
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operator(700,xfx,eqlist).
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operator(700,xfx,lenlist).
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% Rs eqlist L: Rs is a list of lists, whose concatentation is the single list L
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[] eqlist L <=> L=[].
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[R] eqlist L <=> R=L.
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[R|Rs] eqlist [] <=> R=[], Rs eqlist [].
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[[X|R]|Rs] eqlist L <=> L=[X|L1], [R|Rs] eqlist L1.
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Rs eqlist L <=> delete(R,Rs,Rs1),R==[] | Rs1 eqlist L.
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Rs eqlist L <=> delete(R,Rs,Rs1),R==L | Rs1 eqlist [].
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constraints labeling/0.
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labeling, ([R|Rs] eqlist L)#Ph <=> true |
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(var(L) -> length(L,_) ; true),
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(
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R=[], Rs eqlist L
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;
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L=[X|L1], R=[X|R1], [R1|Rs] eqlist L1
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),
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labeling
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pragma passive(Ph).
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% L lenlist N: The length of the list L is N
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% N can be an arithmetic expression
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[] lenlist N <=> true | (var(N) -> N=0 ; N=:=0).
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[_|L] lenlist N <=> positive(N), plus(M,1,N), L lenlist M.
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L lenlist N <=> ground(N) | length(L,N).
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% auxiliary predicates ---------------------------------------------------
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delete( X, [X|L], L).
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delete( Y, [X|Xs], [X|Xt]) :-
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delete( Y, Xs, Xt).
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length([],0).
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length([_|L],N1):- length(L,N), N1 is N+1.
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:- block plus(-,-,?), plus(-,?,-), plus(?,-,-).
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%
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plus( A, B, C) :- var(C), !, C is A+B.
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plus( A, B, C) :- var(B), !, B is C-A.
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plus( A, B, C) :- var(A), !, A is C-B.
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plus( A, B, C) :- C is A+B.
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:- block positive(-).
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%
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positive( X) :- X>0.
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% EXAMPLES ================================================================
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% Inspired by LISTLOG, Z. Farkas, TAPSOFT 87, Pisa, Italy
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% these predicates have better (more fair) enumeration properties
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chr_member(X,L):- [_,[X],_] eqlist L.
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chr_append(L1,L2,L3):- [L1,L2] eqlist L3.
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chr_last(L,X):- [_,[X]] eqlist L.
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/*
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[6]: chr_member(1,L),chr_member(2,L),labeling.
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L = [1, 2] More? (;)
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L = [2, 1] More? (;)
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L = [1, 2, _g1240] More? (;)
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L = [1, _g1062, 2] More? (;)
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L = [2, 1, _g1240] More? (;)
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L = [2, _g1062, 1] More? (;)
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[7]: member(1,L),member(2,L). % compare with usual member/2
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L = [1, 2|_g282] More? (;)
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L = [1, _g280, 2|_g288] More? (;)
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L = [1, _g280, _g286, 2|_g294] More? (;)
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*/
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palindrome([]).
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palindrome([X]).
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palindrome(L):-
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X lenlist 1,
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[X,L1,X] eqlist L,
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palindrome(L1).
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reverse([],[]).
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reverse(R,L):-
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R lenlist N,
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L lenlist N,
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X lenlist 1,
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[X,R1] eqlist R,
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[L1,X] eqlist L,
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reverse(R1,L1).
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/*
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[19]: reverse(X,[a,b]).
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X = [b, a] % does not loop like usual reverse/2
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[10]: reverse([a,b|L],R).
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L = []
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R = [b, a] More? (;)
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L = [_m1718]
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R = [_m1718, b, a] More? (;)
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L = [_m1718, _m2218]
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R = [_m2218, _m1718, b, a] More? (;)
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[11]: reverse(R,[a,b|L]).
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R = [b, a]
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L = [] More? (;)
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R = [_m754, b, a]
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L = [_m754] More? (;)
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R = [_m754, _m1274, b, a]
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L = [_m1274, _m754] More? (;)
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*/
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% Done myself (thom)
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permute([],[]).
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permute(R,L):-
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R lenlist N,
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L lenlist N,
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X lenlist 1,
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[X,R1] eqlist R,
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[A,X,B] eqlist L,
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[A,B] eqlist L1,
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permute(R1,L1).
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/*
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[10]: permute(A,B).
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A = []
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B = [] More? (;)
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A = [_m970]
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B = [_m970] More? (;)
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A = [_m970, _m1994]
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B = [_m2392, _m2416]
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Constraints:
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[_m946, [_m970], _m994] eqlist [_m2392, _m2416]
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[_m946, _m994] eqlist [_m1994]
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More? (;)
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A = [_m970, _m1994, _m3194]
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B = [_m3948, _m3972, _m3996]
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Constraints:
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[_m1970, [_m1994], _m2018] eqlist [_m3592, _m3616]
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[_m946, _m994] eqlist [_m3592, _m3616]
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[_m946, [_m970], _m994] eqlist [_m3948, _m3972, _m3996]
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[_m1970, _m2018] eqlist [_m3194]
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More? (;)
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[11]: permute(A,B),labeling.
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A = []
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B = [] More? (;)
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A = [_m976]
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B = [_m976] More? (;)
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A = [_m976, _m2000]
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B = [_m976, _m2000] More? (;)
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A = [_m976, _m2000]
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B = [_m2000, _m976] More? (;)
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A = [_m976, _m2000, _m3200]
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B = [_m976, _m2000, _m3200] More? (;)
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A = [_m976, _m2000, _m3200]
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B = [_m2000, _m976, _m3200] More? (;)
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A = [_m976, _m2000, _m3200]
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B = [_m2000, _m3200, _m976] More? (;)
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A = [_m976, _m2000, _m3200]
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B = [_m976, _m3200, _m2000] More? (;)
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A = [_m976, _m2000, _m3200]
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B = [_m3200, _m976, _m2000] More? (;)
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A = [_m976, _m2000, _m3200]
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B = [_m3200, _m2000, _m976] More? (;)
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*/
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% From Cohen, Koiran, Perrin "Meta-Level Interpretation of CLP(Lists)"
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% in "CLP: Selected Research", eds Benhamou, Colmerauer, MIT Press 1993.
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% tree(Preorder,Postorder,Tree).
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tree([A],[A],A):- freeze(A,atomic(A)).
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tree(Pre,Post,t(A,L,R)):-
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% Pre lenlist N,
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% Post lenlist N,
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[[A],X,Y] eqlist Pre,
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[Z,W,[A]] eqlist Post,
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tree(X,Z,L),
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tree(Y,W,R).
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/*
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[50]: tree([a, b, b, a, a], [b, a, a, b, a], T).
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T = t(a, b, t(b, a, a))
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*/
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% Inspired by talk by A. Colmerauer, WCLP Marseille, March 1993
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transpose([],L):- [L,[[]]] eqlist [[]|L]. % list of []'s
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transpose([X|R],L):- first_column(L,X,L1), transpose(R,L1).
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first_column([],[],[]).
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first_column([[X|L]|R],[X|S],[L|T]):- first_column(R,S,T).
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/*
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[36]: transpose([[], [], [], []], L_g85).
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L = []
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[37]: transpose(L_g69, [[], [], [], []]).
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L = []
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*/
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/*
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[18]: [X,Y,Z,Z,Y,X] eqlist [a,b,b,c,c,c,c,c,c,b,b,a], labeling.
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Z = [c, c, c]
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Y = [b, b]
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X = [a]
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[21]: [[a],X,[b],Y] eqlist L,
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[Y,[b],X,[a]] eqlist L .
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Y = Y_m654
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X = X_m630
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L = [a|_m678]
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Constraints:
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(3) [X_m630, [b], Y_m654] eqlist _m678
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(4) [Y_m654, [b], X_m630, [a]] eqlist [a|_m678]
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[4]: [[a],X,[b],Y] eqlist L,
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[Y,[b],X,[a]] eqlist L, labeling.
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Y = [a]
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X = []
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L = [a, b, a] More? (;)
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Y = [a]
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X = [b]
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L = [a, b, b, a] More? (;)
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Y = [a, b, a]
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X = []
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L = [a, b, a, b, a] More? (;)
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Y = [a, a]
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X = [a]
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L = [a, a, b, a, a] More? (;)
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Y = [a]
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X = [b, b]
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L = [a, b, b, b, a] More? (;)
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Y = [a]
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X = [b, b, b]
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L = [a, b, b, b, b, a] More? (;)
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*/
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/*
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% Unsolvable equation
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{2]: [[2],X] eqlist L,
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[X,[1]] eqlist L,
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labeling.
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% if there is no more solution for longer lists L, labeling does not terminate
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% Unsolvable equation from dissertation of J.-P. Pecuchet, 1981
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[5]: [[2],X,Y,[1]] eqlist L,
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[X,[1],[2],X] eqlist L,
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labeling.
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% if there is no more solution for longer lists L, labeling does not terminate
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% Solvable equation from paper by K. Schulz, 1988
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[11]: [[1],X,[2],Z,X] eqlist L,
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[Z,[3],Z,Y,Y,Y] eqlist L,
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labeling.
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X = [3, 1, 2, 1, 3, 1]
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Z = [1]
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Y = [2, 1, 3, 1]
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L = [1, 3, 1, 2, 1, 3, 1, 2, 1, 3, 1, 2, 1, 3, 1] More? (;)
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X = [A, 3, 1, A, 2, 1, A, A, 3, 1, A]
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Z = [1, A]
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Y = [2, 1, A, A, 3, 1, A]
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L = [1, A, 3, 1, A, 2, 1, A, A, 3, 1, A, 2, 1, A, A, 3, 1, A, 2, 1, A, A, 3, 1, A] More? (;)
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L = [1,_A,_B,3,1,_A,_B,2,1,_A|...],
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X = [_A,_B,3,1,_A,_B,2,1,_A,_B|...],
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Y = [2,1,_A,_B,_A,_B,3,1,_A,_B],
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Z = [1,_A,_B],
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etc.
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% Solvable equation from talk by A. Colmerauer, WCLP Marseille, March 1993
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[13]: X=[1,2,3,2,1],
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[X,[1]] eqlist L1, [[U],Y,[U,U]] eqlist L1,
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[Y,[2]] eqlist L2, [[V],Z,[V,V]] eqlist L2,
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labeling.
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X = [1, 2, 3, 2, 1]
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U = 1
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L1 = [1, 2, 3, 2, 1, 1]
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Y = [2, 3, 2]
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Z = [3]
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V = 2
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L2 = [2, 3, 2, 2]
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*/
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% end of handler list
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