Making use of the method of subordination chains, we obtain some sufficient conditions for the univalence of an integral operator. In particular, as special cases, our results imply certain known univalence criteria. A refinement to a quasiconformal extension criterion of the main result, is also obtained.
By using the method of Loewner chains, we establish some sufficient conditions for the analyticity and univalency of functions defined by an integral operator. Also, we refine the result to a quasiconformal extension criterion with the help of Beckerss method.
In a previous work, we introduced the Collatz polynomials; these are the polynomials $left[P_N(z)right]_{Ninmathbb{N}}$ such that $left[z^0right]P_N = N$ and $left[z^{k+1}right]P_N = cleft(left[z^kright]P_Nright)$, where $c:mathbb{N}rightarrow mathbb{N}$ is the Collatz function $1rightarrow 0$, $2nrightarrow n$, $2n+1rightarrow 3n+2$ (for example, $P_5(z) = 5 + 8z + 4z^2 + 2z^3 + z^4$). In this article, we prove that all zeros of $P_N$ (which we call Collatz zeros) lie in an annulus centered at the origin, with outer radius 2 and inner radius a function of the largest odd iterate of $N$. Moreover, using an extension of the Enestrom-Kakeya Theorem, we prove that $|z| = 2$ for a root of $P_N$ if and only if the Collatz trajectory of $N$ has a certain form; as a corollary, the set of $N$ for which our upper bound is an equality is sparse in $mathbb{N}$. Inspired by these results, we close with some questions for further study.
We study the boundedness and compactness of the generalized Volterra integral operator on weighted Bergman spaces with doubling weights on the unit disk. A generalized Toeplitz operator is defined and the boundedness, compactness and Schatten class of this operator are investigated on the Hilbert weighted Bergman space. As an application, Schatten class membership of generalized Volterra integral operators are also characterized. Finally, we also get the characterizations of Schatten class membership of generalized Toeplitz operator and generalized Volterra integral operators on the Hardy space $H^2$.
In the present paper, we obtain a more general conditions for univalence of analytic functions in the open unit disk U. Also, we obtain a refinement to a quasiconformal extension criterion of the main result.
In this paper, we introduce the concept of operator arithmetic-geometrically convex functions for positive linear operators and prove some Hermite-Hadamard type inequalities for these functions. As applications, we obtain trace inequalities for operators which give some refinements of previous results. Moreover, some unitarily invariant norm inequalities are established.