email: wortman@math.utah.edu Office: 325 JWB Phone: (801) 585-1628 Fax: (801) 581-4148 |

**Semidualities from products of trees**

(with D. Studenmund) ; Accepted; Geom. Topol.**An Infinitely generated virtual cohomology group for noncocompact arithmetic groups over function fields**

Groups Geom. Dyn. 10 (2016), 91-115.**Horospherical limit points of S-arithmetic groups**

(with D. Morris) ; New York J. Math. 20 (2014), 367-376.**Filling boundaries of coarse manifolds in semisimple and solvable arithmetic groups**

(with M. Bestvina and A. Eskin) ; J. Eur. Math. Soc. 15 (2013) 2165-2195.**On presentations of integer polynomial points of simple groups over number fields**

(with A. Mohammadi); Geom. Dedicata. 164 (2011), 131-137.**Quasi-isometries of irreducible postive-rank arithmetic groups over function fields**

In appendix to ``A Joining classification and a special case of Raghunathan's conjecture in positive characteristic.''

by M. Einsiedler & A. Mohammadi; J. Anal. Math. 116 (2012), 299-334.**Connectivity properties of horospheres in Euclidean buildings and applications to finiteness properties of discrete groups**

(with K.U. Bux); Invent. Math. 185 (2011), 395-419.**Infinite generation of non-cocompact lattices on right-angled buildings**

(with A. Thomas) Algebr. Geom. Topol. 11 (2011), 929-938.**Exponential higher dimensional isoperimetric inequalities for some arithmetic groups**

Geom. Dedicata. 151 (2011), 141-153.**Quasi-isometries of rank one S-arithmetic lattices**

Groups Geom. Dyn. 5 (2011), 787-803.**SL(n,Z[t]) is not FP**_{n-1}

(with K.U. Bux, A. Mohammadi); Comment. Math. Helv. 85 (2010), 151-164.**On Unipotent flows in H(1,1)**

(with K. Calta); Ergodic Theory Dynam. Systems 30 (2010), 121-140.**A Finitely-presented solvable group with a small quasi-isometry group**

Michigan Math. J. 55 (2007), 3-24.**Finiteness properties of arithmetic groups over function fields**

(with Kai-Uwe Bux); Invent. Math. 167 (2007), 355-378.**Quasi-isometric rigidity of higher rank S-arithmetic lattices**

Geom. Topol. 11 (2007), 995-1048.**A Geometric proof that SL(2,Z[t,1/t]) is not finitely presented**

(with Kai-Uwe Bux); Algebr. Geom. Topol. 6 (2006), 839-852.**Quasiflats with holes in reductive groups**

Algebr. Geom. Topol. 6 (2006), 91-117.