On the structure of multivariate hypergeometric terms.
Wilf and Zeilberger conjectured in 1992 that a hypergeometric term is proper if and only if it is holonomic. This conjecture concerns hypergeometric terms which depend on several discrete and continuous variables. The authors prove a slightly modified version of this conjecture in the discrete case, namely that every holonomic hypergeometric term is conjugate to a proper term.
scientific article; zbMATH DE number 1892332