=ADD= =reftype= 14 =number= 00-12 =url= ftp://ftp.risc.uni-linz.ac.at/pub/techreports/2000/00-12.ps.gz =year= 2000 =month= 04 =author= Chyzak; Fr\'ed\'eric =title= About the Non-Minimality of the Outputs of Zeilberger's Algorithm =abstract= We report on case studies where Zeilberger's fast algorithm and the other holonomy-based algorithms known so far for definite hypergeometric summation fail to find the minimal annihilating recurrence satisfied by the sum. To explain the phenomenon we propose a new elimination paradigm, together with a promising heuristic method which we hope to turn into an algorithm in the future. The approach applies to $\partial$-finite functions as well and extends to the related algorithms. =sponsor= SFB grant F1305 of the Austrian Science Foundation (FWF) =keywords= computer algebra, holonomic functions, special functions, symbolic summation