A. Hinkkanen’s research while affiliated with University of Illinois Urbana-Champaign and other places

We give an analytic proof of the dual Smale’s mean value conjecture in the case n=7.

Let f be an entire function and L(f) a linear differential polynomial in f with constant coefficients. Suppose that f, f′$f'$, and L(f) share a meromorphic function α(z)$\alpha (z)$ that is a small function with respect to f. A characterization of the possibilities that may arise was recently obtained by Lahiri. However, one case leaves open many possibilities. We show that this case has more structure than might have been expected, and that a more detailed study of this case involves, among other things, Stirling numbers of the first and second kinds. We prove that the function α$\alpha$ must satisfy a linear homogeneous differential equation with specific coefficients involving only three free parameters, and then f can be obtained from each solution. Examples suggest that only rarely do single-valued solutions α(z)$\alpha (z)$ exist, and even then they are not always small functions for f.

If f is a meromorphic function from the complex plane C${{\mathbb {C}}}$ to the extended complex plane C¯$\overline{ {{\mathbb {C}}} }$, for r>0$r > 0$ let n(r) be the maximum number of solutions in {z:|z|≤r}$\{z:|z| \le r \}$ of f(z)=a$f(z) = a$ for a∈C¯$a \in \overline{ {{\mathbb {C}}} }$, and let A(r, f) be the average number of such solutions. Using a technique introduced by Toppila, we exhibit a meromorphic function for which lim infr→∞n(r)/A(r,f)≥1.07328$\liminf _{r\rightarrow \infty } n(r)/A(r,f) \ge 1.07328$.

We prove that if E is a compact subset of the unit disk ${{\mathbb {D}}}$ in the complex plane, if E contains a sequence of distinct points $a_n\not = 0$ for $n\ge 1$ such that $\lim _{n\rightarrow \infty } a_n=0$ and for all n we have $|a_{n+1}| \ge |a_n|/2$, and if $G={{\mathbb {D}}} {\setminus } E$ is connected and $0\in \partial G$, then there is a constant $c>0$ such that for all $z\in G$ we have $\lambda _{G } (z) \ge c/|z|$ where $\lambda _{G } (z)$ is the density of the hyperbolic metric in G.

We give an analytic proof of the dual Smale's mean value conjecture in the case n=7.

We prove that if E is a compact subset of the unit disk ${\mathbb D}$ in the complex plane, if E contains a sequence of distinct points $a_n\not= 0$ for $n\geq 1$ such that $\lim_{n\to\infty} a_n=0$ and for all n we have $|a_{n+1}| \geq \frac{1}{2} |a_n|$, and if $G={\mathbb D} \setminus E$ is connected and $0\in \partial G$, then there is a constant $c>0$ such that for all $z\in G$ we have $\lambda_{G } (z) \geq c/|z|$ where $\lambda_{G } (z)$ is the density of the hyperbolic metric in G.

We prove that there exists an entire function for which every complex number is an asymptotic value and whose growth is arbitrarily slow subject only to the necessary condition that the function is of infinite order.

We prove that there exists an entire function for which every complex number is an asymptotic value and whose growth is arbitrarily slow subject only to the necessary condition that the function is of infinite order.

If f is an entire function and a is a complex number, a is said to be an asymptotic value of f if there exists a path $\gamma$ from 0 to infinity such that $f(z) - a$ tends to 0 as z tends to infinity along $\gamma$. The Denjoy–Carleman–Ahlfors Theorem asserts that if f has n distinct asymptotic values, then the rate of growth of f is at least order n/2, mean type. A long-standing problem asks whether this conclusion holds for entire functions having n distinct asymptotic (entire) functions, each of growth at most order 1/2, minimal type. In this paper conditions on the function f and associated asymptotic paths are obtained that are sufficient to guarantee that f satisfies the conclusion of the Denjoy–Carleman–Ahlfors Theorem. In addition, for each positive integer n, an example is given of an entire function of order n having n distinct, prescribed asymptotic functions, each of order less than 1/2.