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yap-6.3/GPL/clpqr/clpq/itf_q.pl
2008-03-13 17:16:47 +00:00

222 lines
6.1 KiB
Prolog

/*
Part of CLP(Q) (Constraint Logic Programming over Rationals)
Author: Leslie De Koninck
E-mail: Leslie.DeKoninck@cs.kuleuven.be
WWW: http://www.swi-prolog.org
http://www.ai.univie.ac.at/cgi-bin/tr-online?number+95-09
Copyright (C): 2006, K.U. Leuven and
1992-1995, Austrian Research Institute for
Artificial Intelligence (OFAI),
Vienna, Austria
This software is based on CLP(Q,R) by Christian Holzbaur for SICStus
Prolog and distributed under the license details below with permission from
all mentioned authors.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(itf_q,
[
do_checks/8
]).
:- use_module(bv_q,
[
deref/2,
detach_bounds_vlv/5,
solve/1,
solve_ord_x/3
]).
:- use_module(nf_q,
[
nf/2
]).
:- use_module(store_q,
[
add_linear_11/3,
indep/2,
nf_coeff_of/3
]).
:- use_module('../clpqr/class',
[
class_drop/2
]).
do_checks(Y,Ty,St,Li,Or,Cl,No,Later) :-
numbers_only(Y),
verify_nonzero(No,Y),
verify_type(Ty,St,Y,Later,[]),
verify_lin(Or,Cl,Li,Y),
maplist(call,Later).
numbers_only(Y) :-
( var(Y)
; rational(Y)
; throw(type_error(_X = Y,2,'a rational number',Y))
),
!.
% verify_nonzero(Nonzero,Y)
%
% if Nonzero = nonzero, then verify that Y is not zero
% (if possible, otherwise set Y to be nonzero)
verify_nonzero(nonzero,Y) :-
( var(Y)
-> ( get_attr(Y,itf,Att)
-> setarg(8,Att,nonzero)
; put_attr(Y,itf,t(clpq,n,n,n,n,n,n,nonzero,n,n,n))
)
; Y =\= 0
).
verify_nonzero(n,_). % X is not nonzero
% verify_type(type(Type),strictness(Strict),Y,[OL|OLT],OLT)
%
% if possible verifies whether Y satisfies the type and strictness of X
% if not possible to verify, then returns the constraints that follow from
% the type and strictness
verify_type(type(Type),strictness(Strict),Y) -->
verify_type2(Y,Type,Strict).
verify_type(n,n,_) --> [].
verify_type2(Y,TypeX,StrictX) -->
{var(Y)},
!,
verify_type_var(TypeX,Y,StrictX).
verify_type2(Y,TypeX,StrictX) -->
{verify_type_nonvar(TypeX,Y,StrictX)}.
% verify_type_nonvar(Type,Nonvar,Strictness)
%
% verifies whether the type and strictness are satisfied with the Nonvar
verify_type_nonvar(t_none,_,_).
verify_type_nonvar(t_l(L),Value,S) :- ilb(S,L,Value).
verify_type_nonvar(t_u(U),Value,S) :- iub(S,U,Value).
verify_type_nonvar(t_lu(L,U),Value,S) :-
ilb(S,L,Value),
iub(S,U,Value).
verify_type_nonvar(t_L(L),Value,S) :- ilb(S,L,Value).
verify_type_nonvar(t_U(U),Value,S) :- iub(S,U,Value).
verify_type_nonvar(t_Lu(L,U),Value,S) :-
ilb(S,L,Value),
iub(S,U,Value).
verify_type_nonvar(t_lU(L,U),Value,S) :-
ilb(S,L,Value),
iub(S,U,Value).
% ilb(Strict,Lower,Value) & iub(Strict,Upper,Value)
%
% check whether Value is satisfiable with the given lower/upper bound and
% strictness.
% strictness is encoded as follows:
% 2 = strict lower bound
% 1 = strict upper bound
% 3 = strict lower and upper bound
% 0 = no strict bounds
ilb(S,L,V) :-
S /\ 2 =:= 0,
!,
L =< V. % non-strict
ilb(_,L,V) :- L < V. % strict
iub(S,U,V) :-
S /\ 1 =:= 0,
!,
V =< U. % non-strict
iub(_,U,V) :- V < U. % strict
%
% Running some goals after X=Y simplifies the coding. It should be possible
% to run the goals here and taking care not to put_atts/2 on X ...
%
% verify_type_var(Type,Var,Strictness,[OutList|OutListTail],OutListTail)
%
% returns the inequalities following from a type and strictness satisfaction
% test with Var
verify_type_var(t_none,_,_) --> [].
verify_type_var(t_l(L),Y,S) --> llb(S,L,Y).
verify_type_var(t_u(U),Y,S) --> lub(S,U,Y).
verify_type_var(t_lu(L,U),Y,S) -->
llb(S,L,Y),
lub(S,U,Y).
verify_type_var(t_L(L),Y,S) --> llb(S,L,Y).
verify_type_var(t_U(U),Y,S) --> lub(S,U,Y).
verify_type_var(t_Lu(L,U),Y,S) -->
llb(S,L,Y),
lub(S,U,Y).
verify_type_var(t_lU(L,U),Y,S) -->
llb(S,L,Y),
lub(S,U,Y).
% llb(Strict,Lower,Value,[OL|OLT],OLT) and lub(Strict,Upper,Value,[OL|OLT],OLT)
%
% returns the inequalities following from the lower and upper bounds and the
% strictness see also lb and ub
llb(S,L,V) -->
{S /\ 2 =:= 0},
!,
[clpq:{L =< V}].
llb(_,L,V) --> [clpq:{L < V}].
lub(S,U,V) -->
{S /\ 1 =:= 0},
!,
[clpq:{V =< U}].
lub(_,U,V) --> [clpq:{V < U}].
%
% We used to drop X from the class/basis to avoid trouble with subsequent
% put_atts/2 on X. Now we could let these dead but harmless updates happen.
% In R however, exported bindings might conflict, e.g. 0 \== 0.0
%
% If X is indep and we do _not_ solve for it, we are in deep shit
% because the ordering is violated.
%
verify_lin(order(OrdX),class(Class),lin(LinX),Y) :-
!,
( indep(LinX,OrdX)
-> detach_bounds_vlv(OrdX,LinX,Class,Y,NewLinX),
% if there were bounds, they are requeued already
class_drop(Class,Y),
nf(-Y,NfY),
deref(NfY,LinY),
add_linear_11(NewLinX,LinY,Lind),
( nf_coeff_of(Lind,OrdX,_)
-> % X is element of Lind
solve_ord_x(Lind,OrdX,Class)
; solve(Lind) % X is gone, can safely solve Lind
)
; class_drop(Class,Y),
nf(-Y,NfY),
deref(NfY,LinY),
add_linear_11(LinX,LinY,Lind),
solve(Lind)
).
verify_lin(_,_,_,_).