On extensions of the Laurents' theorem in the fractional calculus with applications to the generation of higer transcendental functions
The classical Mittag-Leffler theorem on meromorphic functions is extended to the case of functions and hyperfunctions belonging to the kernels of linear partial differential operators with constant coefficients.
By combining Turán’s proof of Fabry’s gap theorem with a gap theorem of P. Szüsz we obtain a gap theorem which is more general then both these theorems.
T. Kaluza has given a criterion for the signs of the power series of a function that is the reciprocal of another power series. In this note the sharpness of this condition is explored and various examples in terms of the Gaussian hypergeometric series are given. A criterion for the monotonicity of the quotient of two power series due to M. Biernacki and J. Krzyż is applied.
Multi-dimensional generalizations of the Wiener-Żelazko and Lévy-Żelazko theorems are obtained.
In this paper we give characterizations of those holomorphic functions in the unit disc in the complex plane that can be written as a quotient of functions in A(D), A∞(D) or Λ1(D) with a nonvanishing denominator in D. As a consequence we prove that if f ∈ Λ1(D) does not vanish in D, then there exists g ∈ Λ1(D) which has the same zero set as f in Dbar and such that fg ∈ A∞(D).