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Preparation theorems for matrix valued functions

Nils Dencker (1993)

Annales de l'institut Fourier

We generalize the Malgrange preparation theorem to matrix valued functions F ( t , x ) C ( R × R n ) satisfying the condition that t det F ( t , 0 ) vanishes to finite order at t = 0 . Then we can factor F ( t , x ) = C ( t , x ) P ( t , x ) near (0,0), where C ( t , x ) C is inversible and P ( t , x ) is polynomial function of t depending C on x . The preparation is (essentially) unique, up to functions vanishing to infinite order at x = 0 , if we impose some additional conditions on P ( t , x ) . We also have a generalization of the division theorem, and analytic versions generalizing the Weierstrass preparation...

Prevalence of "nowhere analyticity"

Françoise Bastin, Céline Esser, Samuel Nicolay (2012)

Studia Mathematica

This note brings a complement to the study of genericity of functions which are nowhere analytic mainly in a measure-theoretic sense. We extend this study to Gevrey classes of functions.

Prime rational functions

Omar Kihel, Jesse Larone (2015)

Acta Arithmetica

Let f(x) be a complex rational function. We study conditions under which f(x) cannot be written as the composition of two rational functions which are not units under the operation of function composition. In this case, we say that f(x) is prime. We give sufficient conditions for complex rational functions to be prime in terms of their degrees and their critical values, and we also derive some conditions for the case of complex polynomials.

Principe de la phase résonnante

Jacques Vey (1979)

Annales de l'institut Fourier

On donne une variante du principe de la phase stationnaire, où l’intégrale est remplacée par une sommation sur le réseau cubique de maille égale à l’unité de phase.

Problems and Theorems in the Theory of Multiplier Sequences

Craven, Thomas, Csordas, George (1996)

Serdica Mathematical Journal

The purpose of this paper is (1) to highlight some recent and heretofore unpublished results in the theory of multiplier sequences and (2) to survey some open problems in this area of research. For the sake of clarity of exposition, we have grouped the problems in three subsections, although several of the problems are interrelated. For the reader’s convenience, we have included the pertinent definitions, cited references and related results, and in several instances, elucidated the problems by...

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