Improving Complexity Bounds for the Computation of Puiseux Series over Finite Fields
Adrien Poteaux, Marc Rybowicz · 2015
Let K be a field of characteristic p with q elements and FΕ in L[X,Y] be a polynomial with p> deg_Y(F) and total degree d. In [40], we showed that rational Puiseux series of F above X=0 could be computed with an expected number of O~(d5+d3log q) arithmetic operations in L. In this paper, we reduce this bound to O~(d4+d2log q) using Hensel lifting and changes of variables in the Newton-Puiseux algorithm that give a better control of the number of steps. The only asymptotically fast algorithm required is polynomial multiplication over finite fields. This approach also allows to test the irreducibility of F in L[[X]][Y] with O(d3) operations in K. Finally, we describe a method based on structured bivariate multiplication [34] that may speed up computations for some input.