Contact InformationThomas Keller, Ph.D. Professor Office: MCS 557 Email: tk04@txstate.edu Phone: 512-245-3735 Fax: 512-245-3425 Research InterestGroup theory |

Thomas Keller has a Ph.D. in Mathematics from the University of Mainz, is a Professor of Mathematics and has interests in finite group theory. His recent research is on upper and lower bounds for the number of conjugacy classes of a finite group. He also has work dealing with the longstanding problem of finding a good bound for the derived length of a finite solvable group in terms of the number of its irreducible complex character degrees. Much of his work is based on studying the orbits that are induced by the action of linear groups on finite vector spaces and often involves combinatorial questions as well as problems on permutation groups which are of independent interest.

**Selected Publications:**

- (with A. Gruber, M. L. Lewis, K. A. Naughton, B. Strasser)
*A Characterization of the Prime Graphs of Solvable Groups,*J. Algebra**442**(2015), 397–422. - (with Y. Yang)
*Orbits of finite solvable groups on characters**,*Israel J. Math.**199**(2014), 933–940. *Finite groups have even more conjugacy classes,*Israel J. Math.**181**(2011), 433--444.*Counting characters in linear group actions*, Israel J. Math.**171**(2009), 367--384.*Fixed conjugacy classes of normal subgroups and the k(GV)-problem*, J. Algebra**305**, 457-486 (2006).- (with I. M. Isaacs, M. L. Lewis, A. Moretó)
*Transitive permutation groups in which all derangements are involutions*, J. Pure Appl. Algebra**207**, 717-724 (2006). *Derived length and conjugacy class sizes*, Adv. Math**199**, 88-103 (2006).*The k(GV)-problem revisited*, J. Austral. Math. Soc.**79**, 257-276 (2005).- (with D. Ragan and G. T. Tims)
*On the Taketa bound for normally monomial p-groups of maximal class*}, J. Algebra**277**, 675-688 (2004). *Orbit sizes and character degrees, III*, J. reine angew. Math.**545**, 1-17 (2002).*Orbit sizes and character degrees, II*, J. reine angew. Math.**516**, 27-114 (1999).*Orbit sizes and character degrees*, Pacific J. Math.**187**, 317-332 (1999).*On the asymptotic Taketa bound for A-groups*, J. Algebra**191**, 127-140 (1997).