We extend the notion of monomial extensions of differential fields, i.e. simple transcendental extensions in which the polynomials are closed under differentiation, to difference fields.Expand

Crosspoint switching array, each crosspoint switching circuit including silicon controlled switches for connecting signal lines of one group of transmission lines to signal lines belonging to another group.Expand

The algorithm described here extends the algorithm to nd all polynomial solutions of di erential and di erence equations that was given in [1, 2] to more general operators.Expand

We describe a new direct algorithm for transforming a linear system of recurrences into an equivalent one with nonsingular leading or trailing matrix.Expand

We describe an efficient algorithm for computing the associated equations appearing in the Beke-Schlesinger factorisation method for linear ordinary differential operators.Expand

We introduce structure theorems that refine Liouville's Theorem on integration in closed form for general derivations on multivariate rational function fields, providing theoretical backing for the Risch-Norman integration method.Expand