 
Summary: Hypergeometric dispersion and the orbit problem
Sergei A. Abramov \Lambda
Computer Center of the
Russian Academy of Science
Vavilova 40, Moscow 117967, Russia
abramov@ccas.ru
Manuel Bronstein
INRIA  Projet Caf#
2004, Route des Lucioles, B.P. 93
F06902 Sophia Antipolis Cedex, France
Manuel.Bronstein@sophia.inria.fr
ABSTRACT
We describe an algorithm for ønding the positive integer so
lutions n of orbit problems of the form ff n = fi, where ff
and fi are given elements of a øeld K. Our algorithm cor
rects the bounds given in [7], and shows that the problem
is not polynomial in the Euclidean norms of the polyno
mials involved. Combined with a simpliøed version of the
algorithm of [8] for the ispeciøcation of equivalencej, this
yields a complete algorithm for computing the dispersion of
