295 lines
7.1 KiB
Perl
295 lines
7.1 KiB
Perl
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% clp(q,r) version 1.3.2 %
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% %
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% (c) Copyright 1992,1993,1994,1995 %
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% Austrian Research Institute for Artificial Intelligence (OFAI) %
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% Schottengasse 3 %
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% A-1010 Vienna, Austria %
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% %
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% File: fourmotz.pl %
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% Author: Christian Holzbaur christian@ai.univie.ac.at %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%
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% TODO -) remove syntactic redundancy first ?!!
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% -) avoid the construction of the crossproduct list
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% +) consider strictness in crossproduct generation !!!
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%
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fm_elim( Vs, Target, Pivots) :-
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prefilter( Vs, Vsf),
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fm_elim_int( Vsf, Target, Pivots).
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prefilter( [], []).
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prefilter( [V|Vs], Res) :-
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( get_atts( V, -target),
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occurs( V) ->
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Res = [V|Tail],
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put_atts( V, keep_indep),
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prefilter( Vs, Tail)
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;
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prefilter( Vs, Res)
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).
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%
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% the target variables are marked with an attribute, and we get a list
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% of them as an argument too
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%
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fm_elim_int( [], _, Pivots) :- % done
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unkeep( Pivots).
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fm_elim_int( Vs, Target, Pivots) :-
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Vs = [_|_],
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( best( Vs, Best, Rest) ->
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occurences( Best, Occ),
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elim_min( Best, Occ, Target, Pivots, NewPivots)
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; % give up
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NewPivots=Pivots, Rest = []
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),
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fm_elim_int( Rest, Target, NewPivots).
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%
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% Find the variable with the smallest netto increase on the
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% size of the ineq. system after its elimination
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%
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best( Vs, Best, Rest) :-
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findall( Delta-N, fm_cp_filter( Vs, Delta, N), Deltas),
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keysort( Deltas, [_-N|_]),
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select_nth( Vs, N, Best, Rest).
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fm_cp_filter( Vs, Delta, N) :-
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length( Vs, Len),
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mem( Vs,X,Vst),
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get_atts( X, [-target,lin(Lin)]),
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indep( Lin, X),
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occurences( X, Occ),
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Occ = [_|_],
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% crossproduct( Occ, New, []),
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% length( New, CpLnew),
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cp_card( Occ, 0,Lnew),
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length( Occ, Locc),
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Delta is Lnew-Locc,
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length( Vst, Vstl),
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N is Len-Vstl.
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mem( [X|Xs], X, Xs).
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mem( [_|Ys], X, Xs) :- mem( Ys, X, Xs).
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select_nth( List, N, Nth, Others) :-
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select_nth( List, 1,N, Nth, Others).
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select_nth( [X|Xs], N,N, X, Xs) :- !.
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select_nth( [Y|Ys], M,N, X, [Y|Xs]) :-
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M1 is M+1,
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select_nth( Ys, M1,N, X, Xs).
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%
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% fm_detach + reverse_pivot introduce indep t_none, which
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% invalidates the invariants
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%
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elim_min( V, Occ, Target, Pivots, NewPivots) :-
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crossproduct( Occ, New, []),
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activate_crossproduct( New),
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reverse_pivot( Pivots),
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fm_detach( Occ),
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% length( Occ, Locc), length( New, Lnew), print( fm(-Locc,+Lnew)), nl,
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allvars( V, All),
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redundancy_vars( All), % only for New \== []
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make_target_indep( Target, NewPivots),
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drop_dep( All).
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%
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% restore NF by reverse pivoting
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%
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reverse_pivot( []).
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reverse_pivot( [I:D|Ps]) :-
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get_atts( D, type(Dt)),
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put_atts( D, -keep), % no longer
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pivot( D, I, Dt),
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reverse_pivot( Ps).
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unkeep( []).
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unkeep( [_:D|Ps]) :-
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put_atts( D, -keep),
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drop_dep_one( D),
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unkeep( Ps).
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%
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% All we drop are bounds
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%
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fm_detach( []).
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fm_detach( [V:_|Vs]) :-
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detach_bounds( V),
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fm_detach( Vs).
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%
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% Todo: maybe bulk_basis_add
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%
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activate_crossproduct( []).
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activate_crossproduct( [lez(Strict,Lin)|News]) :-
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arith_eval( 0, Z),
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var_with_def_intern( t_u(Z), Var, Lin, Strict),
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basis_add( Var, _),
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activate_crossproduct( News).
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% ------------------------------------------------------------------------------
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crossproduct( []) --> [].
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crossproduct( [A|As]) -->
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crossproduct( As, A),
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crossproduct( As).
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crossproduct( [], _) --> [].
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crossproduct( [B:Kb|Bs], A:Ka) -->
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{
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get_atts( A, [type(Ta),lin(LinA),strictness(Sa)]),
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get_atts( B, [type(Tb),lin(LinB),strictness(Sb)]),
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arith_eval( -Kb/Ka, K),
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add_linear_f1( LinA, K, LinB, Lin)
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},
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( { arith_eval( K > 0) } -> % signs were opposite
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{ Strict is Sa \/ Sb },
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cross_lower( Ta, Tb, K, Lin, Strict),
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cross_upper( Ta, Tb, K, Lin, Strict)
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; % La =< A =< Ua -> -Ua =< -A =< -La
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{
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flip( Ta, Taf),
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flip_strict( Sa, Saf),
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Strict is Saf \/ Sb
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},
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cross_lower( Taf, Tb, K, Lin, Strict),
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cross_upper( Taf, Tb, K, Lin, Strict)
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),
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crossproduct( Bs, A:Ka).
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cross_lower( Ta, Tb, K, Lin, Strict) -->
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{
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lower( Ta, La),
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lower( Tb, Lb),
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!,
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arith_eval(K*La+Lb,L),
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normalize_scalar( L, Ln),
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arith_eval( -1, Mone),
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add_linear_f1( Lin, Mone, Ln, Lhs),
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Sl is Strict >> 1 % normalize to upper bound
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},
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[ lez(Sl,Lhs) ].
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cross_lower( _, _, _, _, _) --> [].
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cross_upper( Ta, Tb, K, Lin, Strict) -->
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{
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upper( Ta, Ua),
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upper( Tb, Ub),
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!,
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arith_eval(-(K*Ua+Ub),U),
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normalize_scalar( U, Un),
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add_linear_11( Un, Lin, Lhs),
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Su is Strict /\ 2'01 % normalize to upper bound
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},
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[ lez(Su,Lhs) ].
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cross_upper( _, _, _, _, _) --> [].
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lower( t_l(L), L).
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lower( t_lu(L,_), L).
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lower( t_L(L), L).
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lower( t_Lu(L,_), L).
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lower( t_lU(L,_), L).
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upper( t_u(U), U).
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upper( t_lu(_,U), U).
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upper( t_U(U), U).
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upper( t_Lu(_,U), U).
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upper( t_lU(_,U), U).
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flip( t_l(X), t_u(X)).
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flip( t_u(X), t_l(X)).
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flip( t_lu(X,Y),t_lu(Y,X)).
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flip( t_L(X), t_u(X)).
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flip( t_U(X), t_l(X)).
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flip( t_lU(X,Y),t_lu(Y,X)).
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flip( t_Lu(X,Y),t_lu(Y,X)).
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flip_strict( 2'00, 2'00).
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flip_strict( 2'01, 2'10).
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flip_strict( 2'10, 2'01).
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flip_strict( 2'11, 2'11).
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cp_card( [], Ci,Ci).
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cp_card( [A|As], Ci,Co) :-
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cp_card( As, A, Ci,Cii),
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cp_card( As, Cii,Co).
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cp_card( [], _, Ci,Ci).
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cp_card( [B:Kb|Bs], A:Ka, Ci,Co) :-
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get_atts( A, type(Ta)),
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get_atts( B, type(Tb)),
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arith_eval( -Kb/Ka, K),
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( arith_eval( K > 0) -> % signs were opposite
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cp_card_lower( Ta, Tb, Ci,Cii),
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cp_card_upper( Ta, Tb, Cii,Ciii)
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;
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flip( Ta, Taf),
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cp_card_lower( Taf, Tb, Ci,Cii),
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cp_card_upper( Taf, Tb, Cii,Ciii)
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),
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cp_card( Bs, A:Ka, Ciii,Co).
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cp_card_lower( Ta, Tb, Si,So) :-
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lower( Ta, _),
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lower( Tb, _),
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!,
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So is Si+1.
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cp_card_lower( _, _, Si,Si).
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cp_card_upper( Ta, Tb, Si,So) :-
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upper( Ta, _),
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upper( Tb, _),
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!,
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So is Si+1.
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cp_card_upper( _, _, Si,Si).
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% ------------------------------------------------------------------------------
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occurences( V, Occ) :-
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allvars( V, All),
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occurences( All, V, Occ).
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occurences( De, _, []) :- var( De), !.
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occurences( [D|De], V, Occ) :-
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( get_atts( D, [lin(Lin),type(Type)]),
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occ_type_filter( Type),
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nf_coeff_of( Lin, V, K) ->
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Occ = [D:K|Occt],
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occurences( De, V, Occt)
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;
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occurences( De, V, Occ)
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).
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occ_type_filter( t_l(_)).
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occ_type_filter( t_u(_)).
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occ_type_filter( t_lu(_,_)).
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occ_type_filter( t_L(_)).
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occ_type_filter( t_U(_)).
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occ_type_filter( t_lU(_,_)).
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occ_type_filter( t_Lu(_,_)).
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%
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% occurs( V) :- occurences( V, Occ), Occ = [_|_].
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%
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occurs( V) :-
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allvars( V, All),
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occurs( All, V).
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occurs( De, _) :- var( De), !, fail.
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occurs( [D|De], V) :-
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( get_atts( D, [lin(Lin),type(Type)]),
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occ_type_filter( Type),
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nf_coeff_of( Lin, V, _) ->
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true
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;
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occurs( De, V)
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).
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