Parma Polyhedra Library NEWS -- history of user-visible changes
===============================================================
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NEWS for version 0.4.1 (released on July 30, 2002)
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Bugfixes
========
o Fixed a bug in Polyhedron::poly_difference_assign(const Polyhedron& y)
whereby the equality constraints of `y' were ignored (the bug was
affecting both C and NNC computations).
o Fixed a bug in Polyhedron::operator=(const Polyhedron& y). This bug,
which is triggered in some cases when `y' is empty, should only affect
versions of the library obtained with the `--enable-assertions'
configuration flag.
o Fixed a bug in Polyhedron::check_universe(), which was returning
the wrong result when called on a zero-dim universe polyhedron.
o Fixed a bug in NNC_Polyhedron::NNC_Polyhedron(ConSys& cs) whereby
an invariant was violated in case `cs' was empty. This bug
should only affect versions of the library obtained with the
`--enable-assertions' configuration flag.
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NEWS for version 0.4 (released on July 1, 2002)
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New and Changed Features
========================
o Added full support for Not Necessarily Closed (NNC) polyhedra:
- creation of strict inequality constraints and mixed constraint
systems;
- creation of closure points and extended generator systems;
- added classes C_Polyhedron (for the representation of Closed
polyhedra) and NNC_Polyhedron (the user no longer can create
Polyhedron objects);
- added topology compatibility checks to avoid mixing objects of
the two kinds;
- added explicit constructors to create a polyhedron of a given
topology kind starting from a polyhedron of the other kind;
- added methods Polyhedron::is_topologically_closed() and
Polyhedron::topological_closure_assign();
- implemented methods Polyhedron::minimized_constraints() and
Polyhedron::minimized_generators() to obtain minimal
descriptions, both for closed and for NNC polyhedra.
o New method Polyhedron::time_elapse_assign(const Polyhedron&):
it computes the time-elapse operation defined in
N. Halbwachs, Y.-E. Proy, and P. Roumanoff.
Verification of real-time systems using linear relation analysis.
Formal Methods in System Design, 11(2):157-185, 1997.
o New method Polyhedron::is_bounded(): it returns true if and only
if the polyhedron is bounded, i.e., finite.
o New methods Polyhedron::bounds_from_above(const LinExpression& e)
and Polyhedron::bounds_from_below(const LinExpression& e): they
return true if and only if the linear expression `e' is bounded
from above/below in the polyhedron.
o New, complete C interface. As a demo, a toy solver for pure linear
programming problems has been implemented using this interface.
Notice that solving linear programming problems is completely
outside the scope of the library. As a consequence the toy provided
as a demo is only a toy provided as a demo.
o Revised and completed Prolog interface:
- now supporting GNU Prolog, SICStus Prolog, SWI Prolog and YAP.
- all predicates have been renamed to match their intended
semantics;
- arguments have been reordered where necessary so as to follow the
rule "input arguments before output arguments";
- predicates added so that all the public methods for Polyhedra in
the C++ library are available as Prolog predicates;
- the interface has been extended to allow for closed and not
necessarily closed polyhedra.
o Added support for timeout-guarded operations. It is now possible
for client applications to safely interrupt any exponential
computation paths in the library and get control back in a time
that is a linear function of the space dimension of the object
(polyhedron, system of constraints or generators) of highest
dimension on which the library is operating upon.
o The methods named convex_hull_* and convex_difference_*
have been renamed poly_hull_* and poly_difference_*.
o All methods named *_and_minimize() now return a boolean
flag that is false if the result is empty.
o All method and variable names containing the word "vertex"
have been replaced by names containing the word "point"
(some previous uses of the word "vertex" were not formally correct).
o The methods Polyhedron::includes(const Generator&) and
Polyhedron::satisfies(const Constraint&) have been removed,
as well as the enumeration GenSys_Con_Rel.
They have been replaced by the new methods
Polyhedron::relation_with(const Generator&) and
Polyhedron::relation_with(const Constraint&),
which return values of the new enumeration types
Relation_Poly_Gen and Relation_Poly_Con, respectively.
o The method Constraint::coefficient(void) has been renamed
to Constraint::inhomogeneous_term(void).
o The methods Polyhedron::widening_assign() and
Polyhedron::limited_widening_assign() have been renamed
Polyhedron::H79_widening_assign() and
Polyhedron::limited_H79_widening_assign(), respectively.
This emphasizes the fact that they implement extensions
of the widenings introduced in
N. Halbwachs.
Détermination Automatique de Relations Linéaires
Vérifiées par les Variables d'un Programme.
Thèse de 3ème cicle d'informatique,
Université scientifique et médicale de Grenoble,
Grenoble, France, March 1979.
and described in
N. Halbwachs, Y.-E. Proy, and P. Roumanoff.
Verification of real-time systems using linear relation analysis.
Formal Methods in System Design, 11(2):157-185, 1997.
o The library no longer calls abort(): appropriate exceptions
are always thrown instead.
Bugfixes
========
o Fixed a bug whereby creating a point with a negative denominator
caused the library to misbehave.
o Fixed a bug in Polyhedron::add_constraints(ConSys&) whereby
we could have created constraint systems having rows with
different capacities.
o Several other bugs have been fixed.
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NEWS for version 0.3 (released on February 26, 2002)
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New Features
============
o The library has been ported under libtool: it is now possible
to build dynamic libraries as well.
o We now use the integer C++ class of GMP to represent the
coefficients of constraints and generators, instead of our own
(very much inferior) Integer class. The drawback is that we
now require GMP 4.0.1 or higher.
o New methods Polyhedron::convex_difference_assign(const Polyhedron&) and
Polyhedron::convex_difference_assign_and_minimize(const Polyhedron&).
They assigns to *this the convex hull of the set-theoretic difference
of *this and the argument (possibly non minimized or minimized,
respectively).
o The method Polyhedron::add_generators(GenSys&) is now lazy,
i.e., no minimization is performed. Adding generators and
minimizing at the same time is provided by the method
Polyhedron::add_generators_and_minimize(GenSys&).
These methods now throw an exception if the resulting
polyhedron would be illegal.
o Some performance improvements.
o Added more test programs.
Bugfixes
========
o Fixed Polyhedron::satisfies(const Constraint&) and
Polyhedron::affine_image().
o Polyhedron::limited_widening_assign(const Polyhedron&, ConSys&)
was erroneously returning a (random) boolean: it is now a void
method.
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NEWS for version 0.2 (released on November 14, 2001)
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New Features
============
o Massive API changes. This would not normally be called "a feature",
but the old API was very wrong in a number of ways. More API changes
are to be expected for the next few releases.
o All user-accessible library methods are now guarded by suitable
sanity checks. Exception are thrown whenever the library is not
called in the intended way.
o A SICStus Prolog interface is now available. It comes with a somewhat
interesting demo: a toy CLP(Q) interpreter.
o Greatly improved documentation.
Bugfixes
========
o Many, many more than we would like to admit.
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NEWS for version 0.1 (released on October 24, 2001)
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New Features
============
o The library has been released under the GNU General Public License.