Papers

A new measure-conjugacy invariant for actions of free groups. preprint.

Invariant measures on the space of horofunctions of a word hyperbolic group. Submitted. arXiv

Free Groups in Lattices. Submitted.

A Generalization of the Prime Geodesic Theorem to Counting Conjugacy Classes of Free Subgroups. arXiv. Geom. Dedicata 124 (2007), 37--67.

A Solidification Phenomenon in Random Packings  (joint with Russell Lyons, Charles Radin and Peter Winkler). ps. pdf. SIAM J. Math. Anal. 38 (2006), no. 4, 1075--1089 (electronic)

Fluid/Solid Transition in a Hard-Core System (joint with Russell Lyons, Charles Radin and Peter Winkler).Phys. Rev. Lett. 96, 025701 (2006)

On the Gromov Norm of the Product of Two Surfaces  (joint with Mike Develin, Jesus De Loera and Francisco Santos).
Topology 44 (2005), no. 2, 321--339. 57M27 (52B45 57M50). ArXiv.

Periodicity and Circle Packing in the Hyperbolic Plane.
Geom. Dedicata 102 (2003), 213--236. ArXiv.

Uniqueness and symmetry in problems of optimally dense packings (joint with Charles Holton, Charles Radin and Lorenzo Sadun)
Math. Phys. Electron. J.
11 (2005), Paper 1, 34 pp. (electronic). 52A40 (52C23) ArXiv

Couplings of Uniform Spanning Forests
Proc. Amer. Math. Soc. 132 (2004), no. 7, 2151--2158 (electronic). ArXiv

Optimally Dense Packings of Hyperbolic Space (joint with Charles Radin )
Geom. Dedicata 104 (2004), 37--59. ArXiv

On the existence of completely saturated packings and completely reduced coverings
Geom. Dedicata 98 (2003), 211--226. ArXiv

Densest Packing of Equal Spheres in Hyperbolic Space (joint with Charles Radin ).
Discrete Comput. Geom.
29 (2003), no. 1, 23--39.

Circle Packing in Hyperbolic Space
Math. Phys. Electron. J. 6 (2000), Paper 6, 10 pp. (electronic).