Multiple binomial sums

Alin Bostan (1) , Pierre Lairez (2) , Bruno Salvy (3)

1 SPECFUN - Symbolic Special Functions : Fast and Certified
2 Institut für Mathematik [Berlin]
3 ARIC - Arithmetic and Computing

Multiple binomial sums form a large class of multi-indexed sequences, closed under partial summation, which contains most of the sequences obtained by multiple summation of binomial coefficients and also all the sequences with algebraic generating function. We study the representation of the generating functions of binomial sums by integrals of rational functions. The outcome is twofold. Firstly, we show that a univariate sequence is a multiple binomial sum if and only if its generating function is the diagonal of a rational function. Secondly we propose algorithms that decide the equality of multiple binomial sums and that compute recurrence relations for them. In conjunction with geometric simplifications of the integral representations, this approach behaves well in practice. The process avoids the computation of certificates and the problem of accurate summation that afflicts discrete creative telescoping, both in theory and in practice.

Mots clés: Binomial sum; multiple sum; symbolic computation; diagonal; integral representation

Domaines: Calcul formel [cs.SC]; Combinatoire [math.CO]

Alin Bostan, Pierre Lairez, Bruno Salvy. Multiple binomial sums. 2015. ⟨hal-01220573v1⟩