Deciding Hopf bifurcations by quantifier elimination in a software-component architecture

In this paper we give a semi-algebraic description of Hopf bifurcation fixed points for a given parameterized polynomial vector field. The description is carried out by use of the Hurwitz determinants, and produces a first-order formula which is transformed into a quantifier free formula by use of usual quantifier elimination algorithms. We apply techniques from the theory of sub-resultant sequences and of Gr¨obner bases to come up with efficient reductions, which lead to quantifier elimination questions that can often be handled by existing quantifier elimination packages. We could implement the algorithms for the conditions on Hopf bifurcations by combining the computer algebra system Maple with packages for quantifier elimination using a Java based component architecture recently developed by the second author. In addition to some textbook examples we applied our software system to an example discussed in a recent research paper