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yap-6.3/CLPQR/clpqr/bb.yap
vsc 38247e38fc cleanup of CLPQR and CHR;
simplification of module handling;
new timestamp implementation


git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@52 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
2001-06-06 19:10:51 +00:00

133 lines
3.6 KiB
Prolog

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% clp(q,r) version 1.3.3 %
% %
% (c) Copyright 1992,1993,1994,1995 %
% Austrian Research Institute for Artificial Intelligence (OFAI) %
% Schottengasse 3 %
% A-1010 Vienna, Austria %
% %
% File: bb.pl %
% Author: Christian Holzbaur christian@ai.univie.ac.at %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
bb_inf( Is, Term, Inf) :-
bb_inf( Is, Term, Inf, _, 0.001).
bb_inf( Is, Term, Inf, Vertex, Eps) :-
nf( Eps, ENf),
nf_constant( ENf, EpsN),
wait_linear( Term, Nf, bb_inf_internal(Is,Nf,EpsN,Inf,Vertex)).
% ---------------------------------------------------------------------
bb_inf_internal( Is, Lin, Eps, _, _) :-
bb_intern( Is, IsNf),
( bb_delete( incumbent, _) -> true ; true ),
repair( Lin, LinR), % bb_narrow ...
deref( LinR, Lind),
var_with_def_assign( Dep, Lind),
determine_active_dec( Lind),
bb_loop( Dep, IsNf, Eps),
fail.
bb_inf_internal( _, _, _, Inf, Vertex) :-
bb_delete( incumbent, InfVal-Vertex), % GC
{ Inf =:= InfVal }.
bb_loop( Opt, Is, Eps) :-
bb_reoptimize( Opt, Inf),
bb_better_bound( Inf),
vertex_value( Is, Ivs),
( bb_first_nonint( Is, Ivs, Eps, Viol, Floor, Ceiling) ->
bb_branch( Viol, Floor, Ceiling),
bb_loop( Opt, Is, Eps)
;
round_values( Ivs, RoundVertex),
% print( incumbent( Inf-RoundVertex)), nl,
bb_put( incumbent, Inf-RoundVertex)
).
%
% added ineqs may have led to binding
%
%vsc: added ! (01/06/06)
bb_reoptimize( Obj, Inf) :- var( Obj), !, iterate_dec( Obj, Inf).
bb_reoptimize( Obj, Inf) :- nonvar( Obj), Inf = Obj.
bb_better_bound( Inf) :-
bb_get( incumbent, Inc-_),
!,
arith_eval( Inf < Inc).
bb_better_bound( _).
% :- parallel(bb_branch/3).
bb_branch( V, U, _) :- { V =< U }.
bb_branch( V, _, L) :- { V >= L }.
vertex_value( [], []).
vertex_value( [X|Xs], [V|Vs]) :-
rhs_value( X, V),
vertex_value( Xs, Vs).
%vsc: added ! (01/06/06)
rhs_value( Xn, Value) :- nonvar(Xn), !, Value=Xn.
rhs_value( Xn, Value) :- var(Xn),
deref_var( Xn, Xd),
decompose( Xd, _, R, I),
arith_eval( R+I, Value).
%
% Need only one as we branch on the first anyway ...
%
bb_first_nonint( [I|Is], [Rhs|Rhss], Eps, Viol, F, C) :-
( arith_eval( floor(Rhs), Floor),
arith_eval( ceiling(Rhs), Ceiling),
arith_eval(min(Rhs-Floor,Ceiling-Rhs) > Eps) ->
Viol = I,
F = Floor,
C = Ceiling
;
bb_first_nonint( Is, Rhss, Eps, Viol, F, C)
).
round_values( [], []).
round_values( [X|Xs], [Y|Ys]) :-
arith_eval( round(X), Y),
round_values( Xs, Ys).
bb_intern( [], []).
bb_intern( [X|Xs], [Xi|Xis]) :-
nf( X, Xnf),
bb_intern( Xnf, Xi, X),
bb_intern( Xs, Xis).
%
% allow more general expressions and conditions? integral(Exp) ???
%
bb_intern( [], X, _) :- !, arith_eval( 0, X).
bb_intern( [v(I,[])], X, _) :- !, X=I.
bb_intern( [v(One,[X^1])], X, _) :-
arith_eval(One=:=1),
!,
get_atts( X, [type(T),strictness(S)]),
bb_narrow( T, S, X).
bb_intern( _, _, Term) :-
raise_exception( instantiation_error(bb_inf(Term,_,_),1)).
bb_narrow( t_l(L), S, V) :-
S /\ 2'10 =\= 0,
!,
arith_eval( floor(1+L), B),
{ V >= B }.
bb_narrow( t_u(U), S, V) :-
S /\ 2'01 =\= 0,
!,
arith_eval( ceiling(U-1), B),
{ V =< B }.
bb_narrow( t_lu(L,U), S, V) :- !,
bb_narrow( t_l(L), S, V),
bb_narrow( t_u(U), S, V).
bb_narrow( _, _, _).