Displaying similar documents to “On certain subclasses of bounded univalent functions”

A class of analytic functions defined by Ruscheweyh derivative

K. S. Padmanabhan, M. Jayamala (1991)

Annales Polonici Mathematici

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The function f ( z ) = z p + k = 1 a p + k z p + k (p ∈ ℕ = 1,2,3,...) analytic in the unit disk E is said to be in the class K n , p ( h ) if ( D n + p f ) / ( D n + p - 1 f ) h , where D n + p - 1 f = ( z p ) / ( ( 1 - z ) p + n ) * f and h is convex univalent in E with h(0) = 1. We study the class K n , p ( h ) and investigate whether the inclusion relation K n + 1 , p ( h ) K n , p ( h ) holds for p > 1. Some coefficient estimates for the class are also obtained. The class A n , p ( a , h ) of functions satisfying the condition a * ( D n + p f ) / ( D n + p - 1 f ) + ( 1 - a ) * ( D n + p + 1 f ) / ( D n + p f ) h is also studied.

On infinite composition of affine mappings

László Máté (1999)

Fundamenta Mathematicae

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 Let F i = 1 , . . . , N be affine mappings of n . It is well known that if there exists j ≤ 1 such that for every σ 1 , . . . , σ j 1 , . . . , N the composition (1) F σ 1 . . . F σ j is a contraction, then for any infinite sequence σ 1 , σ 2 , . . . 1 , . . . , N and any z n , the sequence (2) F σ 1 . . . F σ n ( z ) is convergent and the limit is independent of z. We prove the following converse result: If (2) is convergent for any z n and any σ = σ 1 , σ 2 , . . . belonging to some subshift Σ of N symbols (and the limit is independent of z), then there exists j ≥ 1 such that for every σ = σ 1 , σ 2 , . . . Σ the composition (1) is a contraction....

A problem of Galambos on Engel expansions

Jun Wu (2000)

Acta Arithmetica

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1. Introduction. Given x in (0,1], let x = [d₁(x),d₂(x),...] denote the Engel expansion of x, that is, (1) x = 1 / d ( x ) + 1 / ( d ( x ) d ( x ) ) + . . . + 1 / ( d ( x ) d ( x ) . . . d n ( x ) ) + . . . , where d j ( x ) , j 1 is a sequence of positive integers satisfying d₁(x) ≥ 2 and d j + 1 ( x ) d j ( x ) for j ≥ 1. (See [3].) In [3], János Galambos proved that for almost all x ∈ (0,1], (2) l i m n d n 1 / n ( x ) = e . He conjectured ([3], P132) that the Hausdorff dimension of the set where (2) fails is one. In this paper, we prove this conjecture: Theorem. d i m H x ( 0 , 1 ] : ( 2 ) f a i l s = 1 . We use L¹ to denote the one-dimensional Lebesgue measure on (0,1] and d i m H to denote...

Subordination results for some subclasses of analytic functions

R. M. El-Ashwah, M. K. Aouf, A. Shamandy, E. E. Ali (2011)

Mathematica Bohemica

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We introduce two classes of analytic functions related to conic domains, using a new linear multiplier Dziok-Srivastava operator D λ , n . q , s ( n 0 = { 0 , 1 , } , q s + 1 ; q , s 0 , 0 α < 1 , λ 0 , 0 ) . Basic properties of these classes are studied, such as coefficient bounds. Various known or new special cases of our results are also pointed out. For these new function classes, we establish subordination theorems and also deduce some corollaries of these results.

Duplicate inverse series relations and hypergeometric evaluations with z = 1 / 4

Wenchang Chu (2002)

Bollettino dell'Unione Matematica Italiana

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The Gould-Hsu (1973) inverse series relations have been systematically applied to the research of hypergeometric identities. Their duplicate version is established and used to demonstrate several terminating F 2 3 1 / 4 -summation formulas. Further hypergeometric evaluations with the same variable are obtained through recurrence relations.

Inessentiality with respect to subspaces

Michael Levin (1995)

Fundamenta Mathematicae

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Let X be a compactum and let A = ( A i , B i ) : i = 1 , 2 , . . . be a countable family of pairs of disjoint subsets of X. Then A is said to be essential on Y ⊂ X if for every closed F i separating A i and B i the intersection ( F i ) Y is not empty. So A is inessential on Y if there exist closed F i separating A i and B i such that F i does not intersect Y. Properties of inessentiality are studied and applied to prove:  Theorem. For every countable family of pairs of disjoint open subsets of a compactum X there exists an open set G ∩ X on...

Intersection topologies with respect to separable GO-spaces and the countable ordinals

M. Jones (1995)

Fundamenta Mathematicae

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Given two topologies, T 1 and T 2 , on the same set X, the intersection topologywith respect to T 1 and T 2 is the topology with basis U 1 U 2 : U 1 T 1 , U 2 T 2 . Equivalently, T is the join of T 1 and T 2 in the lattice of topologies on the set X. Following the work of Reed concerning intersection topologies with respect to the real line and the countable ordinals, Kunen made an extensive investigation of normality, perfectness and ω 1 -compactness in this class of topologies. We demonstrate that the majority of his results...

On the preservation of separation axioms in products

Milan Z. Grulović, Miloš S. Kurilić (1992)

Commentationes Mathematicae Universitatis Carolinae

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We give sufficient and necessary conditions to be fulfilled by a filter Ψ and an ideal Λ in order that the Ψ -quotient space of the Λ -ideal product space preserves T k -properties ( k = 0 , 1 , 2 , 3 , 3 1 2 ) (“in the sense of the Łos theorem”). Tychonoff products, box products and ultraproducts appear as special cases of the general construction.

On the cardinality and weight spectra of compact spaces, II

Istvan Juhász, Saharon Shelah (1998)

Fundamenta Mathematicae

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Let B(κ,λ) be the subalgebra of P(κ) generated by [ κ ] λ . It is shown that if B is any homomorphic image of B(κ,λ) then either | B | < 2 λ or | B | = | B | λ ; moreover, if X is the Stone space of B then either | X | 2 2 λ or | X | = | B | = | B | λ . This implies the existence of 0-dimensional compact T 2 spaces whose cardinality and weight spectra omit lots of singular cardinals of “small” cofinality.

On the positivity of the number of t-core partitions

Ken Ono (1994)

Acta Arithmetica

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A partition of a positive integer n is a nonincreasing sequence of positive integers with sum n . Here we define a special class of partitions. 1. Let t 1 be a positive integer. Any partition of n whose Ferrers graph have no hook numbers divisible by t is known as a t- core partitionof n . The hooks are important in the representation theory of finite symmetric groups and the theory of cranks associated with Ramanujan’s congruences for the ordinary partition function [3, 4, 6]. If t 1 and n 0 ,...