The following technical report is available from
http://aib.informatik.rwth-aachen.de:
On Gröbner Bases in the Context of Satisfiability-Modulo-Theories
Solving over the Real Numbers
Sebastian Junges, Ulrich Loup, Florian Corzilius and Erika Ábrahám
AIB 2013-08
We address satisfiability checking for the first-order theory of the
real-closed field (RCF) using satisfiability-modulo-theories (SMT)
solving. SMT solvers combine a SAT solver to resolve the Boolean
structure of a given formula with theory solvers to verify the
consistency of sets of theory constraints.
In this paper, we report on an integration of Gröbner bases as a theory
solver so that it conforms with the requirements for efficient SMT
solving: (1) it allows the incremental adding and removing of
polynomials from the input set and (2) it can compute an inconsistent
subset of the input constraints if the Gröbner basis contains 1.
We modify Buchberger's algorithm by implementing a new update operator
to optimize the Gröbner basis and provide two methods to handle
inequalities. Our implementation uses special data structures tuned to
be efficient for huge sets of sparse polynomials. Besides solving, the
resulting module can be used to simplify constraints before being passed
to other RCF theory solvers based on, e.g., the cylindrical algebraic
decomposition.