
CS Seminar: David Merchat, May 24, 2005
 Speaker

Dr. David Merchat,
VERIMAGIMAG
Gières, France.
 Date and Time

Tuesday, May 24, 2005 at 16:00
 Place

Sala Riunioni,
Dipartimento di Matematica,
Università di Parma,
I43100 Parma
 Title

Reducing the number of numerical variables in linear relations analysis
 Abstract

The seminar describes research work done in the field of automatic
verification of numerical properties, mainly for embedded systems.
During verification one must represent, in a finite way, the possibly
infinite set of values that a tuple of program variables can take.
The domain of convex polyhedra offers one possible solution to this
problem. This representation is precise but expensive, so that the
number of program variables one can simultaneously approximate is
limited. The goal of the research we present is to increase the
maximum number of variables that it is possible to represent without
incurring excessive computational costs. Two approaches have been
considered and tested. First we wanted to benefit from the presence
of linear equations in order to eliminate variables from the
representation (as values for these variables could be recovered by
means of the equations). Experimentation showed that this approach
does not perform well in practice. Another approach, more promising,
is the use of the cartesian product. The idea is to represent
independently the variables whose evolution is not dependent. This
decomposition can be improved through a change of basis. We will
discuss the experimental results obtained with an analyser we
developed in order to test these two approaches.
 Contact Person

Roberto Bagnara
[Page last updated on May 23, 2005, 08:53:47.]
