Kauers, Manuel; Zeilberger, Doron Experiments with a positivity-preserving operator. (English) Zbl 1157.05003 Exp. Math. 17, No. 3, 341-345 (2008). Summary: We consider some multivariate rational functions that have (or are conjectured to have) only positive coefficients in their series expansion. We consider an operator that preserves positivity of series coefficients, and apply the inverse of this operator to the rational functions. We obtain new rational functions that seem to have only positive coefficients, whose positivity would imply positivity of the original series, and that, in a certain sense, cannot be improved any further. Cited in 4 Documents MSC: 05A15 Exact enumeration problems, generating functions 33F10 Symbolic computation of special functions (Gosper and Zeilberger algorithms, etc.) Keywords:positivity; special functions; computer algebra × Cite Format Result Cite Review PDF Full Text: DOI arXiv Euclid