• Commutative Algebra (tight closure, test ideals, Hilbert-Kunz functions)
• Mathematics of Phylogenetics

Publications

• Hilbert-Kunz functions of normal rings, with C. Huneke and P. Monsky, Math. Res. Letters 11 (2004), no. 4, 539-546. (Paper at MRL)
  (Paper) (Abstract)
• Test ideals in diagonal hypersurface rings II, Journal of Algebra 264 (2003), 296-304. (from Science Direct)
  (Paper) (Abstract)
• Tight closure, plus closure and Frobenius closure in cubical cones,
  Trans. Amer. Math. Soc., 352 (2000), pp. 95-114. (Abstract, references, links to article at Transactions site)
  (Paper)(Abstract)
• Test ideals in diagonal hypersurface rings, Journal of Algebra 237(2001), 38-48.
  (from Science Direct)
  (Paper) (Abstract)
• Regular closure, Proc. Amer. Math. Soc. 127 (1999), pp. 1975-1979.
  (Abstract, references, links to article at Proceedings site.)
  (Paper)(Abstract)
• Strongly bounded rings, Journal of Algebra 199 (1998), 690-702.
  (from Science Direct)
  (Paper)(Abstract)

• Active Learning in Abstract Algebra: An Arsenal of Techniques, with s. belcastro and L. Burton, in Innovations in Teaching Abstract Algebra, eds. Allen C. Hibbard and Ellen Parker, MAA Notes, 60, Math. Assoc. of Amer., Washington, D.C., 2002. (pdf)