Functional decomposition ofpolynomials: the tame case

  • Authors:
  • Joachim von zur Gathen

  • Affiliations:
  • -

  • Venue:
  • Journal of Symbolic Computation - Special issue on computational algebraic complexity
  • Year:
  • 1990

Quantified Score

Hi-index 0.00

Visualization

Abstract

If g and h are polynomials of degrees r and s over a field, their functional composition f=g(h) has degree n=rs. The functional decomposition problem is: given f of degree n=rs, determine whether such g and h exist, and, in the affirmative case, compute them. We first deal with univariate polynomials, and present sequential algorithms that use O(n log^2n log log n) arithmetic operations, and a parallel algorithm with optimal depth O(log n). Then we consider the case where f and h are multivariate, and g is univariate. All algorithms work only in the ''tame'' case, where the characteristic of the field does not divide r.