2 research outputs found
Functional Decomposition using Principal Subfields
Let be a univariate rational function. It is well known that any
non-trivial decomposition , with , corresponds to a
non-trivial subfield and vice-versa. In
this paper we use the idea of principal subfields and fast
subfield-intersection techniques to compute the subfield lattice of
. This yields a Las Vegas type algorithm with improved complexity
and better run times for finding all non-equivalent complete decompositions of
.Comment: 8 pages, accepted for ISSAC'1