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Results on the deficiencies of some differential-difference polynomials of meromorphic functions

Xiu-Min Zheng, Hong-Yan Xu (2016)

Open Mathematics

In this paper, we study the relation between the deficiencies concerning a meromorphic function f(z), its derivative f′(z) and differential-difference monomials f(z)mf(z+c)f′(z), f(z+c)nf′(z), f(z)mf(z+c). The main results of this paper are listed as follows: Let f(z) be a meromorphic function of finite order satisfying lim sup r→+∞ T(r, f) T(r,  f ′ ) <+∞, lim sup r + T ( r , f ) T ( r , f ' ) < + , and c be a non-zero complex constant, then δ(∞, f(z)m f(z+c)f′(z))≥δ(∞, f′) and δ(∞,f(z+c)nf′(z))≥ δ(∞, f′). We also investigate the value...

Ruelle operator with nonexpansive IFS

Ka-Sing Lau, Yuan-Ling Ye (2001)

Studia Mathematica

The Ruelle operator and the associated Perron-Frobenius property have been extensively studied in dynamical systems. Recently the theory has been adapted to iterated function systems (IFS) ( X , w j j = 1 m , p j j = 1 m ) , where the w j ’s are contractive self-maps on a compact subset X d and the p j ’s are positive Dini functions on X [FL]. In this paper we consider Ruelle operators defined by weakly contractive IFS and nonexpansive IFS. It is known that in such cases, positive bounded eigenfunctions may not exist in general. Our theorems...

Secant tree calculus

Dominique Foata, Guo-Niu Han (2014)

Open Mathematics

A true Tree Calculus is being developed to make a joint study of the two statistics “eoc” (end of minimal chain) and “pom” (parent of maximum leaf) on the set of secant trees. Their joint distribution restricted to the set {eoc-pom ≤ 1} is shown to satisfy two partial difference equation systems, to be symmetric and to be expressed in the form of an explicit three-variable generating function.

Second order difference inclusions of monotone type

G. Apreutesei, N. Apreutesei (2012)

Mathematica Bohemica

The existence of anti-periodic solutions is studied for a second order difference inclusion associated with a maximal monotone operator in Hilbert spaces. It is the discrete analogue of a well-studied class of differential equations.

Second order linear q -difference equations: nonoscillation and asymptotics

Pavel Řehák (2011)

Czechoslovak Mathematical Journal

The paper can be understood as a completion of the q -Karamata theory along with a related discussion on the asymptotic behavior of solutions to the linear q -difference equations. The q -Karamata theory was recently introduced as the theory of regularly varying like functions on the lattice q 0 : = { q k : k 0 } with q > 1 . In addition to recalling the existing concepts of q -regular variation and q -rapid variation we introduce q -regularly bounded functions and prove many related properties. The q -Karamata theory is then...

Sets of k -recurrence but not ( k + 1 ) -recurrence

Nikos Frantzikinakis, Emmanuel Lesigne, Máté Wierdl (2006)

Annales de l’institut Fourier

For every k , we produce a set of integers which is k -recurrent but not ( k + 1 ) -recurrent. This extends a result of Furstenberg who produced a 1 -recurrent set which is not 2 -recurrent. We discuss a similar result for convergence of multiple ergodic averages. We also point out a combinatorial consequence related to Szemerédi’s theorem.

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