István Györi

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This paper presents a generalization of the classical compartmental models using the concept of "pipes" between the compartments and taking into account the time needed for the material to pass through these pipes. A general linear delay differential system describing such models is derived and some properties of its solutions-such as nonnegativity,(More)
In this paper we give easily verifiable, but sharp (in most cases necessary and sufficient) algebraic conditions for the solutions of systems of higher order linear difference equations to be periodic. The main tool in our investigation is a transformation, recently introduced by the authors, which formulates a given higher order recursion as a first order(More)