https://inria.hal.science/inria-00072862Bronstein, ManuelManuelBronsteinCAFE - Computer algebra and functional equations - CRISAM - Inria Sophia Antipolis - Méditerranée - Inria - Institut National de Recherche en Informatique et en AutomatiqueOn solutions of Linear Ordinary Difference Equations in their Coefficient FieldHAL CCSD1999DIFFERENCE EQUATIONSQ-DIFFERENCE EQUATIONSRATIONAL SOLUTIONSHYPERGEOMETRIC COEFFICIENTS[INFO.INFO-OH] Computer Science [cs]/Other [cs.OH]Inria, Rapport De Recherche2006-05-24 11:07:262023-03-15 08:58:082006-05-31 14:24:27enReportsapplication/pdf1We extend the notion of monomial extensions of differential fields, i.e. simp- le transcendental extensions in which the polynomials are closed under differentiation, to difference fields. The structure of such extensions provides an algebraic framework for solving generalized linear difference equations with coefficients in such fields. We then describe algorithms for finding the denominator of any solution of those equations in an important subclass of monomial extensions that includes transcendental indefinite sums and products. This reduces the general problem of finding the solutions of such equations in their coefficient fields to bounding their degrees. In the base case, this yields in particular a new algorithm for computing the rational solutions of q-difference equations with polynomial coefficients.