I  am associate professor  and Director of Undergraduate Studies in the mathematics department at the University at Buffalo, SUNY.    My office is 211 in the mathematics buildling and my office phone is 716-645-8775.

Previous to coming to Buffalo I was an associate professor at the University of Toledo mathematics department .

Snail mail:      
        244 Mathematics Building
        Buffalo, NY  14260-2900.  

Spring 2012 Office Hours: 

                Monday: 11-12,  Thursday 10:30-11:30 or by appt.

    **Office hours are for my students, for academic advising please call the undergraduate secretary Patti Wieclaw at 645-8785 to schedule an appointment.                  
                        

Email me:  dhemmer@math.buffalo.edu                                

My CV:   Here is my CV as of May 2011.

My Research:
           
            Here is a  research statement  designed for those in my field.

            Here is a research statement designed to be accessible to undergraduate math majors.                                 

Publications:

• "The Ext¹  quiver for completely splittable representations of the symmetric group,"  Journal of Group Theory, (4)   (2001) #4, p. 401-416. pdf    dvi ps
• "Support varieties for modules over symmetric groups," (With Dan Nakano) Journal of Algebra, (254) (2002), p. 422-440. pdf
  
• "Specht filtrations for Hecke algebras of type A," (With Dan Nakano),  J. London Math Society (2) (69) (2004), p. 623-638. pdf
  
• "Fixed-point functors  for symmetric groups and Schur algebras," J. Algebra (280) (2004), p. 295-312.  pdf
• "A row removal theorem for the Ext^1 quiver of symmetric groups and Schur algebras,"  Proc. American Mathematical Society, ( 133)  (2005), p.403-414.   dvi     pdf
• "Representation Type of Schur Superalgebras," (With Kujawa and Nakano), J. Group Theory, (9) (2006) #3, p. 283-306.   pdf   ps
• "Irreducible Specht modules are signed Young modules," J. Algebra (305) (2006) , p.433-441  pdf
• "Cohomology of Specht modules," (with Nakano) J. Algebra (306)  (2006), p. 191-200.   pdf
  
• "Symmetric Group Modules with Specht and Dual Specht Filtrations," Communications in Algebra, 35:11, (2007) 3292 - 3306  pdf
  
• "Cohomology and generic cohomology of Specht modules for the symmetric group," J. Algebra (322) (2009),  1498-1515. pdf
• "The complexity of certain Specht modules for the symmetric group,"  Journal of Algebraic Combinatorics, (30) (2009), 421-427.  pdf
• "The group of endotrivial modules for the symmetric and alternating groups," (With Jon Carlson and Nadia Mazza), Proc. Edin. Math. Soc. (2010) 53, 83–95 .  pdf
• "On the cohomology of Young modules for the symmetric group," (With Fred Cohen and Dan Nakano), Advances in Mathematics (224) (2010), 1419-1461.   pdf
• "Stable decompositions for some symmetric group characters arising in braid group cohomology,"  Journal of Combinatorial Theory Series A, (118) (2011) 1136-1139.  pdf
• "A combinatorial approach to Specht module cohomology," to appear, Algebra Colloq.  2011.   pdf
• "Realizing large gaps in cohomology for symmetric group modules," to appear, Algebra and Number Theory 2011.  pdf
  

• My doctoral disseration (final version! 6/01)  dvi ps

• American Contract Bridge League
• AMS Math on the Web
  
• Groups, Representations and Cohomology Preprint Archive