Analyticity on families of circles

Testing analyticity on circles

Consider a continuous one parameter family of circles in complex plane that contains two circles lying in the exterior of one another. Under mild assumptions on the family, we prove that if a continuous function on the union of the above circles extends holomorphically into each circle, then the function is holomorphic in the interior of the union of the circles.

Analyticity of functions analytic on circles

Let U be the closed unit disc in C and let p be a point on the unit circle. Let f be a continuous function on U which extends holomorphically from each circle contained in U and centered at the origin, and from each circle contained in U and passing through the point p. Then f is holomorphic in the interior of U.

多项式 Misiurewicz 族上 Hausdorff 维数的解析性与度量结构

Analyticity of the Hausdorff dimension and metric structures on Misiurewicz families of polynomials

本文在多项式 Misiurewicz 族的有界稳定分支上，利用热力学形式体系与转移算子的谱隙构造自然路径度量，从而建立具有动力学意义的几何，并重新得到 Julia 集 Hausdorff 维数解析变化的结果。

Applications of Envelopes

Intuitively, an envelope of a family of curves is a curve that is tangent to a member of the family at each point. Here we use envelopes of families of circles to study objects from matrix theory and hyperbolic geometry. First we explore relationships between numerical ranges of $2\times 2$ matrices and families of circles to study the elliptical range theorem. Then we deduce a relationship between envelopes and the boundaries of families of intersecting circles and use it to find the boundaries of various families of pseudohyperbolic disks.

Meromorphic extensions from small families of circles and holomorphic extensions from spheres

Let B be the open unit ball in C^2 and let a, b, c be three points in C^2 which do not lie in a complex line, such that the complex line through a and b meets B and such that <a|b> is different from 1 if one of the points a, b is in B and the other in the complement of B and such that at least one of the numbers <a|c>, <b|c> is different from 1. We prove that if a continuous function f on the sphere bB extends holomorphically into B along each complex line which passes through one of the points a, b, c then f extends holomorphically through B. This generalizes recent work of L.Baracco who prov…

Quasisymmetric geometry of the Cantor circles as the Julia sets of rational maps

We give three families of parabolic rational maps and show that every Cantor set of circles as the Julia set of a non-hyperbolic rational map must be quasisymmetrically equivalent to the Julia set of one map in these families for suitable parameters. Combining a result obtained before, we give a complete classification of the Cantor circles Julia sets in the sense of quasisymmetric equivalence. Moreover, we study the regularity of the components of the Cantor circles Julia sets and establish a sufficient and necessary condition when a component of a Cantor circles Julia set is a quasicircle.