Differential transcendence & algebraicity criteria for the series counting weighted quadrant walks

Abstract

We consider weighted small step walks in the positive quadrant, and provide algebraicity and differential transcendence results for the underlying generating functions: we prove that depending on the probabilities of allowed steps, certain of the generating functions are algebraic over the field of rational functions, while some others do not satisfy any algebraic differential equation with rational function coefficients. Our techniques involve differential Galois theory for difference equations as well as complex analysis (Weierstrass parameterization of elliptic curves). We also extend to the weighted case many key intermediate results, as a theorem of analytic continuation of the generating functions.

36 pages, 9 figures, to appear in Publications mathématiques de Besançon

References in corpus (4)

• On the nature of the generating series of walks in the quarter plane
• On the Holonomy or Algebraicity of Generating Functions Counting Lattice Walks in the Quarter-Plane
• Galois Groups of Difference Equations of Order Two on Elliptic Curves
• Infinite Orders and Non-$D$-finite Property of $3$-Dimensional Lattice Walks

Cited by in corpus (3)

• On the Kernel curves associated with walks in the quarter plane
• On the nature of four models of symmetric walks avoiding a quadrant
• Differential transcendence criteria for second-order linear difference equations and elliptic hypergeometric functions