On the complexity of computing with zero-dimensional triangular sets

Adrien Poteaux (1, 2) , Éric Schost (3)

1 CALFOR - Calcul Formel
2 LIFL - Laboratoire d'Informatique Fondamentale de Lille
3 Computer Science Department

We study the complexity of some fundamental operations for triangular sets in dimension zero. Using Las Vegas algorithms, we prove that one can perform such operations as change of order, equiprojectable decomposition, or quasi-inverse computation with a cost that is essentially that of modular composition. Over an abstract field, this leads to a subquadratic cost (with respect to the degree of the underlying algebraic set). Over a finite field, in a boolean \RAM\ model, we obtain a quasi-linear running time using Kedlaya and Umansʼ algorithm for modular composition. Conversely, we also show how to reduce the problem of modular composition to change of order for triangular sets, so that all these problems are essentially equivalent. Our algorithms are implemented in Maple; we present some experimental results.

Mots clés: Equiprojectable decomposition

Domaines: Calcul formel [cs.SC]

Adrien Poteaux, Éric Schost. On the complexity of computing with zero-dimensional triangular sets. Journal of Symbolic Computation, 2013, 50, pp.110 - 138. ⟨10.1016/j.jsc.2012.05.008⟩. ⟨hal-00825847⟩