Summary: Linear Diophantine equations over polynomials and soft decoding of
Reed­Solomon codes
Michael Alekhnovich #
October 20, 2004
Abstract
We generalize the classical Knuth­Sch˜onhage algorithm computing GCD of two polynomials
for solving arbitrary linear Diophantine systems over polynomials in time, quasi­linear in the
maximal degree. As an application, we consider the following weighted curve fitting problem:
given a set of points in the plain, find an algebraic curve (satisfying certain degree conditions)
that goes through each point the prescribed number of times. The main motivation for this
problem comes from the coding theory, namely it is ultimately related to the list decoding of
Reed­Solomon codes.
We present a new fast algorithm for the weighted curve fitting problem, based on the ex­
plicit construction of Groebner basis. This gives another fast algorithm for the soft decoding
of Reed­Solomon codes di#erent from the procedure proposed by Feng, which works in time
( w
r
) O(1) n log 2 n, where r is the rate of the code, and w is the maximal weight assigned to a
vertical line.
1. Preliminaries

Source: Alekhnovich, Michael - Institute for Advanced Study, Princeton University

Collections: Mathematics; Computer Technologies and Information Sciences