Article Contents
Article Contents

# Hereditarily non uniformly perfect sets

This work was partially supported by a grant from the Simons Foundation (#318239 to Rich Stankewitz). The research of the third author was partially supported by JSPS KAKENHI 24540211, 15K04899. The authors would also like to thank the referees for their helpful comments that improved the presentation of this paper

• We introduce the concept of hereditarily non uniformly perfect sets, compact sets for which no compact subset is uniformly perfect, and compare them with the following: Hausdorff dimension zero sets, logarithmic capacity zero sets, Lebesgue 2-dimensional measure zero sets, and porous sets. In particular, we give a detailed construction of a compact set in the plane of Hausdorff dimension 2 (and positive logarithmic capacity) which is hereditarily non uniformly perfect.

Mathematics Subject Classification: Primary: 31A15, 30C85, 37F35.

 Citation:

• Table 1.  Does $X$ imply $Y$ when $E \subset {\mathbb C}$ is a compact set?

 $\dim_H E=0$ Cap $E = 0$ $E$ is HNUP $m_2(E)=0$ $E$ is porous $\dim_H E=0$ $\ast$ $yes^1$ $no^2$ $no^3$ $no^4$ Cap $E = 0$ $no^5$ $\ast$ $no^6$ $no^7$ $no^8$ $E$ is HNUP $yes^9$ $yes^{10}$ $\ast$ $no^{11}$ $no^{12}$ $m_2(E)=0$ $yes^{13}$ $yes^{14}$ $no^{15}$ $\ast$ $yes^{16}$ $E$ is porous $no^{17}$ $no^{18}$ $no^{19}$ $no^{20}$ $\ast$
•  [1] L. V. Ahlfors, Conformal Invariants: Topics in Geometric Function Theory, McGraw-Hill Book Co., New York-Düsseldorf-Johannesburg, 1973, McGraw-Hill Series in Higher Mathematics. [2] A. F. Beardon and C. Pommerenke, The Poincaré metric of plane domains, J. London Math. Soc. (2), 18 (1978), 475-483.  doi: 10.1112/jlms/s2-18.3.475. [3] R. Broderick, L. Fishman, D. Kleinbock, A. Reich and B. Weiss, The set of badly approximable vectors is strongly ${$C^1$}$ incompressible, Math. Proc. Cambridge Philos. Soc., 153 (2012), 319-339.  doi: 10.1017/S0305004112000242. [4] K. J. Falconer, The Geometry of Fractal Sets, vol. 85 of Cambridge Tracts in Mathematics, Cambridge University Press, Cambridge, 1986. [5] K. Falconer, Fractal Geometry, 3rd edition, John Wiley & Sons, Ltd., Chichester, 2014, Mathematical foundations and applications. [6] N. Falkner, Mathematical review of "Construction of measure by mass distribution", J. Yeh, Real Anal. Exchange, 35 (2010), 501-507. http://www.ams.org/mathscinet-getitem?mr=2683615. [7] S. D. Fisher, Function Theory on Planar Domains - A Second Course in Complex Analysis, John Wiley & Sons, New York, 1983. [8] L. Fishman, D. Simmons and M. Urbański, Diophantine approximation and the geometry of limit sets in Gromov hyperbolic metric spaces, Mem. Amer. Math. Soc., 254 (2018), v+137 pp. doi: 10.1090/memo/1215. [9] P. Järvi and M. Vuorinen, Uniformly perfect sets and quasiregular mappings, J. London Math. Soc. (2), 54 (1996), 515-529.  doi: 10.1112/jlms/54.3.515. [10] C. T. McMullen, Winning sets, quasiconformal maps and Diophantine approximation, Geom. Funct. Anal., 20 (2010), 726-740.  doi: 10.1007/s00039-010-0078-3. [11] C. Pommerenke, Uniformly perfect sets and the Poincaré metric, Arch. Math., 32 (1979), 192-199.  doi: 10.1007/BF01238490. [12] T. Ransford, Potential Theory in the Complex Plane, vol. 28 of London Mathematical Society Student Texts, Cambridge University Press, Cambridge, 1995. doi: 10.1017/CBO9780511623776. [13] T. Sugawa, Uniformly perfect sets: Analytic and geometric aspects [translation of Sūgaku, 53 (2001), 387-402; mr1869018], Sugaku Expositions, 16 (2003), 225-242. [14] M. Tsuji, Potential Theory in Modern Function Theory, Maruzen, Tokyo, 1959.

Tables(1)