108 lines
3.0 KiB
Perl
108 lines
3.0 KiB
Perl
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% PATH CONSISTENCY to be used with time.pl
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% thom fruehwirth ECRC 921030,930212,930802,930804,930908,931216,931223
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% christian holzbaur 961022 more mods for Sicstus
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% thom fruehwirth LMU 980206, 980312
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:- use_module(library(chr)).
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:- use_module( library('chr/ordering'), [globalize/1,var_compare/3]).
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nonground( X) :- \+ ground( X).
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handler path_consistency.
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constraints arc/4, path/6.
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% arc(X,Y,L,T) there is an arc in the constraint network between variables X and Y with constraint L of type T
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% path(N,X,Y,L,T,I) there is a path in the constraint network between variables X and Y with constraint L of type T
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%% start up
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add_path @
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arc(X,Y,L,T) <=> ground(L),ground(T),length(L,N) |
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globalize(X-Y), % attach attribute to vars to have order on them
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path(N,X,Y,L,T,1).
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%% ground case
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ground @
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path(N,X,Y,L,T,I) <=> ground(X-Y-L-T) | path1(N,X,Y,L,T,I).
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%% simple cases
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empty @
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path(N,X,Y,L,T,I) <=> empty(N,L,T) | fail.
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universal @
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path(N,X,Y,L,T,I) <=> universal(N,L,T) | true.
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equality @
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path(N,X,X,L,T,I) <=> equality(L,T).
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unify @
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path(1,X,Y,L,T,I) <=> unique(L),equality(L,T) | X=Y. % can cause problems with var order
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%% special cases for finite domains
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findom_unique @
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path(1,X,Y,L,p-p,I) <=> number(X),unique(L) | bind_value(X,Y,L).
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findom_x @
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path(N,X,Y,L,p-p,I) <=> number(X),X=\=0
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shift_interval(X,L,L1),
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path(N,0,Y,L1,p-p,I).
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findom_y @
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path(N,Y,X,L,p-p,I) <=> number(X)
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equality([Eq],p-p),transl(L,L2,[Eq],p-p-p), % invert path
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shift_interval(X,L2,L1),
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path(N,0,Y,L1,p-p,I).
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%% intersection (has to come before transitivity)
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intersect_xy_xy @
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path(N1, X, Y, L1, U-V, I), path(N2, X, Y, L2, U-V, J) <=> % 10
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intersection(L1, L2, L3, U-V),
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length(L3, N3),
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K is min(I, J),
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path(N3, X, Y, L3, U-V, K)
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pragma already_in_heads.
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intersect_yx_xy @
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path(N1, Y, X, L1, U-V, I), path(N2, X, Y, L, V-U, J) <=> % 11
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equality([Eq], V-V), transl(L, L2, [Eq], V-U-V), % invert 2nd path
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intersection(L1, L2, L3, U-V),
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length(L3, N3),
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K is min(I, J),
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path(N3, Y, X, L3, U-V, K).
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%% transitivity
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propagate_xy_yz @
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path(N1, X, Y, L1, U-V, I), path(N2, Y, Z, L2, V-W, J) ==>
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nonground(Y),
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J=1, (I=1 -> var_compare( <, X, Z) ; true) % or J=1 or N2=1 or X@<Z
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transl(L1, L2, L3, U-V-W),
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length(L3, M),
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K is I+J,
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path(M, X, Z, L3, U-W, K).
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propagate_xy_xz @
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path(N1, X, Y, L1, U-V, I), path(N2, X, Z, L3, U-W, J) ==>
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nonground(X),
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min(I, J)=:=1, var_compare( <, Y, Z) % or J=1 or N2=1
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transl(L1, L2, L3, U-V-W),
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length(L2, M),
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K is I+J,
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path(M, Y, Z, L2, V-W, K).
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propagate_xy_zy @
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path(N1, X, Y, L3, U-V, I), path(N2, Z, Y, L2, W-V, J) ==>
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nonground(Y),
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min(I, J)=:=1, var_compare( <, X, Z) % or J=1 or N2=1
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transl(L1, L2, L3, U-W-V),
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length(L1, M),
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K is I+J,
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path(M, X, Z, L1, U-W, K).
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%% labeling by choice of primitive relation
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constraints labeling/0.
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labeling, path(N, X, Y, L, T, I)#Id <=> N>1 |
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member(R, L),
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path(1, X, Y, [R], T, I),
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labeling
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pragma passive(Id).
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/*--------------- eof pc.chr ------------------------------------------------*/
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