Auburn University

Auburn, Alabama, 36849

tel: 334-844-4290

fax: 334-844-6555

hks0015@auburn.edu

Department of Mathematics

Rosemary Kopel Brown Eminent Scholars Chair, 2019-

Department of Mathematics

Professor and Chair, 2017-2019.

Department of Mathematics

Associate Chair, 2012-2015.

Professor, 2012-2017.

Associate Professor, 2007-2012.

Department of Mathematics

Professor, 2008.

Associate Professor, 2005-2008.

Assistant Professor, 2001-2005.

Department of Mathematics

NSF postdoctoral research fellow, 2000-2001.

Department of Mathematics

NSF postdoctoral research fellow, 1998-2000.

Department of Mathematics

Visiting Assistant Professor, 1997-1998.

Ph.D. in Mathematics, 1997.

M.S. in Mathematics, 1994.

B.S. in Applied Mathematics and Computer Science, 1986.

Parachutist Badge, Expert Field Medical Badge, Meritorious Service Medal,

Army Commendation Medal, Army Achievement Medal, Overseas Service Ribbon.

Iowa State University, Office of the Provost: Early Achievement in Departmental Leadership, 2019.

Iowa State University, Veterans Center: Outstanding Partner Award, 2019.

Iowa State University, Division of Student Affairs: Wilbur L. Layton Faculty Recognition Award, 2019.

University of Illinois, College of Arts and Sciences: Dean's award for Excellence in Undergraduate Teaching, 2015.

Fulbright Visiting Professor, Universidad de Buenos Aires, 2014.

American Mathematical Society, Invited Hour Address, Southeast Sectional Meeting, New Orleans, 2012.

Texas A&M University, Department of Mathematics: Outstanding service award, 2006.

Cornell University, College of Arts and Sciences: Clark Distinguished Teaching award, 1997.

NSF grant (RTG-Combinatorics, computation and applications at Iowa State), 2019-2024.

NSF grant (Symbolic computation meets computational geometry), 2018-2021.

Simons grant (Applied algebraic geometry), 2017-2022.

UIUC grant (Grad student research fellowship), 2016-2017.

NSF grant (Systemic risk and topology), 2013-2016.

Fulbright grant (Multigraded algebra and surface modelling), 2014.

UIUC grant (Grad student research fellowship), 2014-2015.

NSF grant (Combinatorial commutative algebra), 2011-2014.

NSA grant (Toric varieties, Hyperplane arrangements, Splines), 2011-2013.

NSF grant (Conference: Syzygies in Berlin), 2013.

UIUC grant (Grad student research fellowship), 2012-2013.

UIUC grant (Grad student research fellowship), 2010-2011.

NSF grant (Surface modeling, approximation theory, and coding theory), 2007-2010.

NSA grant (Applied commutative algebra), 2007-2009.

NSF grant (Symbolic computations in algebra and topology), 2003-2006.

NSA grant (Texas algebraic geometry conference), 2006.

ATP grant (Non-standard splines for geometric modeling), 2004-2006.

NSA grant (Algebra and combinatorics of line arrangements in P^2), 2003-2005.

NSF grant (CBMS conference grant), 2002.

NSF grant (Postdoctoral research fellowship) 1998-2001.

Postdoctoral research fellowship, MSRI, 1998 (declined).

Graduate fellowship,Mathematical Sciences Institute, 1995.

Chair, Committee of Academic Sponsors, MSRI, (2020-present).

Member (ex officio), Board of Trustees, MSRI, (2020-present).

Managing Editor, Advances in Applied Mathematics, (2018-present).

Editorial Board, Data Science in the Mathematical Sciences, (2021-present).

Editorial Board, Journal of Combinatorial Algebra, (2016-present).

Editorial Board, Journal of Commutative Algebra, (2017-present).

Managing Editor, Journal of Commutative Algebra, (2008-17).

Editorial Board, Advances in Applied Mathematics, (2014-17).

Editorial Board, International Journal of Algebra and Computation, (2011-17).

Member, AMS-SIAM-MAA Employment Committee (2016-19).

Member, AMS Mathematical Research Community Advisory board (2008-15).

Member, AMS Data Committee (2006-08).

Chair, ISU Math (2017-19).

Executive Committee (elected), UIUC Math (2016-17).

Associate Chair, UIUC Math (2012-15).

Teaching Awards Committee, UIUC Math (chair, 2015-16).

Math Prizes Committee, UIUC Math (chair, 2013-15).

Promotion & Tenure Committee, UIUC Math (2012-14).

Postdoctoral Committee, UIUC Math (chair, 2011-12).

Executive Committee (elected), UIUC Math (2009-11).

Graduate Affairs Committee UIUC Math (chair, 2009).

Graduate Affairs Committee UIUC Math (2008-09).

Executive Committee (elected), Texas A&M Math (2005-07).

Committee to redesign Engineering Linear Algebra, Texas A&M Math (chair, 2006).

co-Chair, Closing the Achievement Gap for Veterans Committee, ISU (2018-20).

Chair, Statistics Department Chair Search Committee, ISU (2018-19).

Committee to Assess Evaluation of Teaching, ISU (2018-19).

Committee on Veterans and Military Affiliated Students, ISU (2019-20).

Campus Research Board, UIUC (2016-17).

Campus General Education Board, UIUC (2015-16).

Graduate College Doctoral Program Assessment Committee, UIUC (2015-16).

Graduate College Postdoctoral Committee, UIUC (2013-15).

College of Arts and Sciences Awards Committee, UIUC (2012-14).

College of Arts and Sciences Centennial Committee, UIUC (2013-14).

**Recent Conference Organization**

Organizer, INdAM conference "Approximation Theory and Numerical Analysis meet Algebra, Geometry, Topology", (with M. Lanini, C. Manni), Cortona, Italy, 9/2022.

Organizer, MFO Miniworkshop "Interpolation, Approximation, Algebra", (with C. de Boor, T. Sauer, T. Sorokina), Oberwolfach, 2/2022.

Organizer, SIAM conference "Applied algebraic geometry", (with J. Yu), Texas A&M, 8/2021.

Organizer, MFO workshop "Toric geometry", (with D. Maclagan, J. Hausen), Oberwolfach, 9/2019.

Organizer, workshop "Ideals, Varieties, Applications", (with L. Buse,
C. D'Andrea, A. Dickenstein, R. Goldman, J. Sidman), Amherst, 6/2019.

Organizer, NSF-Berkeley workshop "Progress on free resolutions", (with
D. Eisenbud, S. Mapes, B. Stone, D. Swinarski, A. Taylor), Berkeley, 7/2017.

Organizer, BIRS-CMO workshop "Computational algebra and surface modeling", (with L. Buse, R. Goldman), Oaxaca, 8/2016.

Organizer, MFO workshop "Toric geometry", (with D. Maclagan, J. Hausen), Oberwolfach, 3/2016.

Organizer, ICERM workshop "Computational topology in arrangement theory", (with N. Budur, G. Denham, A. Macinic, D. Matei, L. Maxim, M. Wakefield), Brown University, 7/2015.

Organizer, MFO workshop "Splines and algebraic geometry", (with L. Schumaker, T. Sorokina), Oberwolfach, 4/2015.

Organizer, AMS special session on Toric geometry, (with C. Berkesch, D. Erman), 10/2014.

Organizer, Macaulay2 workshop and conference (with D. Eisenbud, D. Grayson, S. Mapes, M. Stillman), UIUC, 6/2014.

Organizer, Math/Engineering workshop “Applied topology and geometry” (with A. Hirani), UIUC, 2/2014.

Organizer, SIAM summer school "Toric Geometry" (with J. Little), Ft. Collins, 8/2013.

Organizer, NSF-DFG workshop "Syzygies in Berlin" (with D. Eisenbud, F.O. Schreyer, R. Panharipande), 5/2013.

Organizer, AMS special session on Approximation theory and algebraic geometry, New Orleans, 10/2012.

Organizer, NSF conference "Commutative Algebra and Algebraic Geometry", (with S. Dutta), UIUC, 11/2011.

Scientific Committee, PIMS conference: "Arrangements and applications",
Vancouver, Canada, 8/2011.

Scientific Committee, MSRI-INdAM workshop "Toric Varieties",
Cortona, Italy, 7/2011.

Organizer, MSRI summer graduate student workshop "Toric Varieties" (with D. Cox), Berkeley, CA, 6/2009.

Organizer, AMS-NSF Math Research Community workshop "Computational algebra and convexity" (with M. Stillman, J. Verschelde), Snowbird, UT, 6/2008.

Organizer, MFO Miniworkshop "Surface modelling" (with D. Cox, A. Dickenstein, J. Schicho), Oberwolfach, 11/2007.

Organizer, BIRS Focussed Research Group "Complex Arrangements" (with S. Yuzvinsky), Banff, 6/2006.

Organizer, NSA--Texas Algebraic Geometry Conference (with Hassett, Keel, Landsberg, Sottile), Texas A&M University, 5/2006.

**Graduate Student and Postdoctoral Advising**

Sean Grate, current (Auburn)

Joanie Morris, current (Auburn)

Beihui Yuan, Ph.D. 2021 (Cornell) (joint with Stillman)

Matt Mastroeni, Ph.D. 2018 (UIUC)

Eliana Duarte, Ph.D. 2017 (UIUC)

Nathan Fieldsteel, Ph.D. 2017 (UIUC)

Michael Dipasquale, Ph.D. 2015 (UIUC)

Jimmy Shan, Ph.D. 2014 (UIUC)

Alexandra Seceleanu, Ph.D. 2011 (UIUC)

Jimmy Kimball, Ph.D. 2008 (Texas A&M)

Stefan Tohaneanu, Ph.D. 2007 (Texas A&M)

Terry McDonald, Ph.D. 2006 (Texas A&M)

Jayan Mukerjee, ICERM bridge postdoc 2021-2022

Mucyo Karemera, Auburn postdoc 2021-2022 (joint with Molinari)

Bill Trok, Auburn postdoc 2020-2021 (joint with Oeding)

Javid Validashti, Illinois postdoc 2011-2014

Leah Gold, NSF-VIGRE postdoc 2002-2005

"Algebraic foundations for applied topology and data analysis",

Springer Verlag, to appear.

"Toric varieties", (with D. Cox, J. Little)

AMS Graduate Studies in Mathematics, 2011.

"Computational Algebraic Geometry'',

Cambridge University Press, 2003.

"Calabi-Yau threefolds in P^n and Gorenstein rings", (with M. Stillman, B. Yuan),

Advances in Theoretical and Mathematical Physics, to appear.

"Algebraic properties of Hermitian sums of squares", (with J. Brooks, D. Grundmeier),

Proceedings of the A.M.S., 150 (2022), 347-3476.

"Schemes supported on the singular locus of a hyperplane arrangement in P^n", (with J. Migliore, U. Nagel),

International Mathematics Research Notices, 1, (2022), 140-170.

"The simplest minimal free resolutions in P^1 x P^1", (with N. Botbol and A. Dickenstein), in

Commutative Algebra, Springer Verlag (2021), 113-145.

"The Hessian polynomial and the Jacobian ideal of a reduced hypersurface in P^n", (with L. Buse, A. Dimca, G. Sticlaru),

Advances in Mathematics, 392, (2021), 22pp.

"Quadratic Gorenstein rings and the Koszul property, I", (with M. Mastroeni, M. Stillman),

Transactions of the A.M.S., 374, (2021), 1077-1093.

"Quadratic Gorenstein rings and the Koszul property, II", (with M. Mastroeni, M. Stillman),

International Mathematics Research Notices, to appear.

"Rees algebras, syzygies, and geometric modeling", in Applications of Polynomial Systems (by D. Cox),

CBMS Conference Series in Mathematics 134, (2020), 121-135.

"The Weak Lefschetz property for quotients by Quadratic Monomials", (with J. Migliore, U. Nagel),

Mathematica Scandinavica, 126, (2020), 41-61.

"Trading Networks and Hodge Theory", (with R. Sowers, R. Song),

Journal of Physics Communications, (2020), 21pp.

"A new bound for smooth spline spaces", (with M. Stillman, B. Yuan),

Journal of Combinatorial Algebra, 4, (2020), 359-367.

"Stratifying Multiparameter Persistent Homology", (with H. Harrington, N. Otter, U. Tillmann)

SIAM Journal on Applied Algebra and Geometry, 3, (2019), 439-471.

"Logarithmic vector fields for curve arrangements in P^2 with quasihomogeneous singularities", (with H. Terao, M. Yoshinaga)

Math. Research Letters, 25, (2018), 1977-1992.

"The method of shifted partial derivatives cannot separate the permanent from the determinant", (with K. Efremenko, J.M. Landsberg, J. Weyman)

Mathematics of Computation, 87, (2018), 2037-2045.

"On minimal free resolutions of subpermanents and other ideals arising in complexity theory", (with K. Efremenko, J.M. Landsberg, J. Weyman)

Journal of Algebra, 503, (2018), 8-20.

"Subdivision and spline spaces", (with Tatyana Sorokina),

Constructive Approximation, 47, (2018), 237-247.

"Codes from surfaces with small Picard number", (with J. Little)

SIAM Journal on Applied Algebra and Geometry, 2, (2018), 242-258.

"Polynomial interpolation in higher dimension: from simplicial complexes to geometrically characterized sets", (with Nathan Fieldsteel),

SIAM Journal on Numerical Analysis, 55 (2017), 131-143.

"Algebraic methods in approximation theory",

Computer Aided Geometric Design, 45 (2016), 14-31.

"Tensor product surfaces and linear syzygies", (with E. Duarte)

Proceedings of the A.M.S., 144 (2016), 65-72.

"Chen ranks and resonance", (with D. Cohen)

Advances in Mathematics, 285 (2015), 1-27.

"Finitely many smooth d-polytopes with n lattice points", (with T. Bogart, C. Haase, M. Hering, B. Lorenz, B. Nill, A. Paffenholz, G. Rote, F. Santos)

Israel Journal of Mathematics, 207, (2015), 301-330.

"Geometry of Wachspress surfaces", (with C. Irving)

Algebra & Number Theory, 8 (2014), 369-396.

"Splines on the Alfeld split of a simplex and type A root systems",

Journal of Approximation Theory, 182 (2014), 1-6.

"Syzygies and singularities of tensor product surfaces of bidgree (2,1)", (with A. Seceleanu, J. Validashti)

Mathematics of Computation, 83 (2014), 1337-1372.

"Local cohomology of logarithmic forms", (with G. Denham, M. Schulze, M. Wakefield, U. Walther)

Annales de l'Institut Fourier, 63 (2013), 1177-1203.

"Toric Hirzebruch-Riemann-Roch via Ishida's theorem on the Todd genus",

Proceedings of the A.M.S., 141 (2013), 1215-1217.

"Commutative algebra of subspace and hyperplane arrangements", (with J. Sidman)

Springer Verlag "Commutative Algebra" (2013), 639-665.

"High rank linear syzygies on low rank quadrics", (with M. Stillman)

American Journal of Mathematics, 134 (2012), 561-579.

"Equivariant Chow cohomology of nonsimplicial toric varieties",

Transactions of the A.M.S., 364 (2012) 4041-4051.

"Hyperplane Arrangements: Computations and Conjectures",

Advanced Studies in Pure Mathematics, 62 (2012) 323-358.

"Resonance varieties via blowups of P^2 and scrolls",

International Math Research Notices, 20 (2011) 4756-4778.

"Inverse systems, Gelfand-Tsetlin patterns, and the weak Lefschetz property", (with B. Harbourne, A. Seceleanu)

Journal of the L.M.S., 84, (2011) 712-730.

"Euler characteristic of coherent sheaves on simplicial torics via the Stanley-Reisner ring",

Journal of Mathematical Physics, 51, (2010) doi 112304.

"The weak Lefschetz property and powers of linear forms in K[x,y,z]", (with A. Seceleanu)

Proceedings of the A.M.S., 138 (2010) 2335-2339.

"Freeness of Conic-Line arrangements in P^2", (with S. Tohaneanu)

Commentarii Mathematici Helvetici, 84 (2009) 235-258.

"Piecewise polynomials on polyhedral complexes", (with T. McDonald)

Advances in Applied Mathematics, 42 (2009), 82-93.

"The Orlik-Terao algebra and 2-formality", (with S. Tohaneanu)

Mathematical Research Letters, 16 (2009), 171-182.

"Holonomy Lie algebras and the LCS formula for subarrangements of A_n", (with P. Lima-Filho)

International Math Research Notices, 8 (2009) 1421-1432.

"Efficient computation of resonance varieties via Grassmannians" (with P. Lima-Filho),

Journal of Pure and Applied Algebra, 213 (2009), 1606-1611.

"Betti numbers and degree bounds for some linked zero-schemes", (with L. Gold and H. Srinivasan)

Journal of Pure and Applied Algebra, 210, (2007), 481-491.

"A case study in bigraded commutative algebra", (with D. Cox and A. Dickenstein)

in "Syzygies and Hilbert Functions'', I. Peeva, ed., Lecture notes in Pure and Applied Mathematics 254, (2007), 67--112.

"Syzygies, multigraded regularity and toric varieties'', (with M. Hering and G. Smith)

Compositio Mathematica, 142, (2006), 1499-1506.

"Toric surface codes and Minkowski sums'', (with J. Little)

SIAM Journal on Discrete Mathematics, 20, (2006), 999-1014.

"Derivation modules of orthogonal duals of hyperplane arrangements'', (with J.P.S. Kung)

Journal of Algebraic Combinatorics, 24, (2006), 253-262.

"Linear syzygies, Chen ranks, and the Bernstein-Gelfand-Gelfand correspondence'', (with A. Suciu)

Transactions of the A.M.S., 358, (2006), p. 2269-2289.

"Cayley-Bacharach and evaluation codes on complete intersections'', (with L. Gold and J. Little)

Journal of Pure and Applied Algebra, 196, (2005) p. 91-99.

"Linear systems on a special rational surface'',

Mathematical Research Letters, 11, (2004) p. 697-714.

"Lattice polygons and Green's theorem'',

Proceedings of the A.M.S., 132, (2004) p. 3509-3512.

"Elementary modifications and line configurations in P^2'',

Commentarii Mathematici Helvetici, 78, (2003) p. 447-462.

"Local complete intersections in P^2 and Koszul syzygies'', (with D. Cox)

Proceedings of the A.M.S., 131, (2003) p. 2007-2014.

"Lower central series and free resolutions of hyperplane arrangements'', (with A. Suciu)

Transactions of the A.M.S., 354, (2002) p. 3409-3433.

"Cohomology vanishing and a problem in approximation theory'', (with P. Stiller)

Manuscripta Mathematica, 107, (2002) p. 43-58.

"The module of logarithmic p-forms of a locally free arrangement'', (with M. Mustata)

Journal of Algebra, 241, (2001) p. 699-719.

"On a conjecture of Rose'', (with J. Dalbec)

Journal of Pure and Applied Algebra, 165, (2001) p. 151-154.

"A rank two vector bundle associated to a three arrangement, and its Chern polynomial'',

Advances in Mathematics, 149, (2000) p. 214-229.

"Subalgebras of the Stanley-Reisner ring'',

Discrete and Computational Geometry, 21, (1999) p. 551-556.

"Fat points, inverse systems, and piecewise polynomial functions'', (with A. Geramita)

Journal of Algebra, 204, (1998) p. 116-128.

"A spectral sequence for splines'',

Advances in Applied Mathematics, 19, (1997) p. 183-199.

"Local cohomology of bivariate splines'', (with M. Stillman)

Journal of Pure and Applied Algebra,117-118, (1997) p. 535-548.

"A family of ideals of minimal regularity and the Hilbert series of C^r(Delta)'', (with M. Stillman)

Advances in Applied Mathematics, 19, (1997) p. 169-182.

Applied Algebra and Geometry, Swansea 12/21 (virtual).

"From approximation theory to Castelnuovo-Mumford regularity of vector bundles''

Algebraic Geometry (Alex Dimca Retirement), Ischia, Italy 10/21.

"Symmetry: from physics of Calabi-Yau threefolds to algebra of Gorenstein rings'',

Chern Institute, Symposium on Physics and Geometry, Nankai 8/21 (virtual).

"New Bounds for Planar Splines'',

Universita Roma (Tor Vergata) workshop on algebraic approaches to multivariate splines, Rome 5/21 (virtual).

"Castelnuovo-Mumford regularity of the Jacobian of a Hypersurface'',

MFO Workshop on Logarithmic vector fields and freeness of divisors, Oberwolfach 1/21 (virtual).

IPM Workshop on Commutative Algebra, Tehran 1/21 (virtual).

"Calabi-Yau threefolds in P^n and Gorenstein rings'',

MSRI National Commutative Algebra/Algebra Geometry Seminar, 11/20 (virtual).

"Castelnuovo-Mumford regularity of the Jacobian of a Hypersurface'',

Arrangements at Home Conference, online, 8/20 (virtual).

Frei University Berlin Algebra Seminar, Berlin, Germany 6/20 (virtual).

"Algebraic Methods in Topological Data Analysis'',

CIMAT graduate-postdoc workshop (4.5 hours of lecture), Guanajuato, Mexico, 1/20.

"Syzygies: from theory to applications'',

CIMPA graduate-postdoc workshop (8 hours of lecture and computer labs), Joao Pessoa, Brazil, 11/19.

"Lefschetz, Linkage, and Quadratic Gorenstein non-Koszul algebras'',

CIRM workshop on Lefschetz properties, Marseille, France, 10/19.

"Toric Varieties'',

MSRI-NCTS summer graduate workshop (10 hours of lecture), Taipei, Taiwan, 8/19.

"Stratifying Multiparameter Persistent Homology'',

ICERM workshop "Nonlinear algebra and applications", Brown University, 11/18.

"Geometric Modeling and Syzygies'',

ARCADES doctoral school "Algebraic representations in Computer-Aided Design", Barcelona, 9/18.

"Stratifying Multiparameter Persistent Homology'',

BIRS-CMO workshop "Multiparameter Persistent Homology", Oaxaca, Mexico, 8/18.

"Quadratic Gorenstein non-Koszul algebras via idealization'',

BIRS workshop on Progress on Syzygies, Banff, Canada, 6/18.

"Rees algebras, syzygies, and computational geometry'',

CBMS workshop on applications of polynomial systems, TCU, 6/18.

"The Lefschetz property for quadratic monomial ideals'',

Mittag-Leffler Conference on Lefschetz properties, Stockholm, Sweden, 7/17

"Multiparameter Persistent Homology'',

Centro di Giorgi conference on Combinatorics, Geometry, and Topology, Pisa, Italy, 6/17

"Syzygies, Exterior Algebra, and Hyperplane Arrangements'',

KIAS Conference on Syzygies, Exterior algebras, and cohomology, Jeju, Korea, 8/16

"Polynomial Interpolation: from GC sets to simplicial complexes'',

Mathematical methods for curves and surfaces, Tonsberg, Norway, 6/16.

"The Weak Lefschetz Property for quadratic monomial quotients'',

INdAM conference on Homological and Computational Algebra, Cortona, Italy, 6/16.

"The Weak Lefschetz Property and Bernstein-Gelfand-Gelfand'',

BIRS workshop on Lefschetz Properties and Artinian Algebras, Banff, Canada, 3/16.

"Logarithmic vector fields and curve arrangements'',

MFO workshop on Arrangements of Subvarieties and Applications, Oberwolfach, Germany, 3/16.

"Approximation theory and root systems of type A arrangements'',

ICERM conference on computational topology of arrangements, Brown University, 7/15.

"Trading networks and Hodge theory'',

Conference on Geometry and Data Analysis, University of Chicago, 6/15.

"Geometry of generalized barycentric coordinates'',

ICMS conference on free resolutions, Betti numbers, and combinatorics, Edinburgh, Scotland, 6/15.

"Algebraic methods in approximation theory'',

MFO workshop on multivariate splines, Oberwolfach, Germany, 4/15.

"Wachspress varieties and geometric modeling'',

FoCM Foundations of computational mathematics conference, Montevideo, Uruguay, 12/14.

"Chen ranks and resonance'',

INdAM conference on Configuration Spaces, Cortona, Italy, 9/14.

"Quasihomogeneous curve configurations and addition/deletion theorems for logarithmic bundles'',

BIRS FRG on Hyperplane arrangements and wonderful compactifications, Banff, Canada, 4/14.

"Logarithmic vector fields for curve configurations in the projective plane'',

RIMS conference on Characteristic classes and arrangements, Kyoto, Japan, 11/13.

"Geometry of Wachspress surfaces'',

SIAM minisymposium on computations and effective bounds in commutative algebra, Colorado State University, 8/13.

"Syzygies and singularities of tensor product surfaces'',

SIAM minisymposium on toric geometry, lattice points, and applications, Colorado State University, 8/13.

"Toric varieties'',

SIAM graduate-postdoc workshop "Math in the Mountains" (2 lectures and problem sessions), Colorado, 7/13.

"Syzygies and combinatorics'',

NSF-DFG graduate-postdoc workshop "Syzygies in Berlin'' (series of 4 lectures), Berlin, Germany, 5/13.

"Geometry of Wachspress surfaces'',

BIRS workshop on Algebraic geometry and geometric modelling, Banff, Canada, 1/13.

"Logarithmic vector fields for curve configurations in the projective plane'',

MSRI seminar, Berkeley, 12/12.

"Equivariant Chow cohomology of nonsimplicial toric varieties'',

MFO workshop on cohomology rings and fundamental groups of arrangements, Oberwolfach, Germany, 10/12.

"From approximation theory to algebraic geometry: The ubiquity of splines'',

AMS Sectional meeting invited hour address, New Orleans, 10/12.

"Logarithmic vector fields and quasihomogeneous curve configurations'',

AMS special session on combinatorial commutative algebra, New Orleans, 10/12.

"Syzygies and toric varieties'',

MFO workshop on toric geometry, Oberwolfach, Germany, 4/12.

"The weak Lefschetz property and powers of linear forms'',

KUMUNU Conference on commutative algebra, University of Nebraska, 4/11.

"Cohomology and Chow rings of toric varieties'',

BIRS workshop on Topological methods in toric and symplectic geometry, Banff, Canada, 11/10.

"Linear series and linear syzygies'',

MFO miniworkshop on Linear series on algebraic varieties, Oberwolfach, Germany, 10/10.

"Equivariant Chow cohomology of nonsimplicial toric varieties'',

Configuration Spaces: Geometry, Combinatorics and Topology, Centro de Giorgi, Pisa, Italy, 6/10.

AMS special session on zonotopal algebra, San Francisco, 1/10.

"Arrangements and Computations'' (series of 3 one-hour lectures),

Math Society of Japan summer school on Arrangements, Hokkaido, Japan, 8/09.

"Logarithmic forms for quasihomogeneous curve configurations in P^2'',

AIM squares workshop on Logarithmic forms, arrangements and D-modules, Palo Alto, 5/09.

"Toric specializations of the Rees algebra of Koszul cycles'',

AMS special session on algebra and number theory with polyhedra, San Francisco, 4/09.

"Piecewise polynomials on polyhedral complexes'',

Conference on algebraic geometry and approximation theory, Towson, MD, 4/09.

"Geometry and syzygies of surfaces associated to line configurations in P^2'',

Bluegrass Algebra Conference, University of Kentucky, 3/09.

"The Orlik-Terao algebra and 2-formality'',

Fields Institute conference in honor of Peter Orlik, Toronto, 8/08.

"Open problems on Hilbert functions and syzygies'',

AMS-NSF Mathematical Research Community Workshop, Snowbird, 6/08.

"Computational algebra and problems in algebraic topology and numerical analysis'',

Cornell Conference on Macaulay2, Ithaca 3/08.

"Algebra and geometry of four sections of O(2,1)'',

MFO miniworkshop on surface modelling and syzygies, Oberwolfach, Germany, 11/07.

"A syzygy approach to projective normality'',

MFO miniworkshop on projective normality of smooth toric varieties, Oberwolfach, Germany, 8/07.

"Splines on polyhedral complexes",

BIRS workshop on Commutative Algebra, Banff, Canada, 6/07.

"Syzygies of plane curve singularities",

MSRI workshop on Advances in Algebra and Geometry, Berkeley, 4/07.

"Toric surface codes and Minkowski sums",

AMS Special Session on low dimensional varieties, New Orleans, LA, 1/07.

"A spectral sequence stratification of cohomology jump loci",

AMS Special Session on Arrangements and related topics, New Orleans, LA, 1/07.

"Configurations of smooth rational curves in P^2",

BIRS workshop on Hilbert functions and Syzygies, Banff, Canada, 10/06.

"Fitting ideals and cohomology jump loci",

MSRI workshop on Configuration Spaces and Arrangements, Berkeley, 8/06.

"R^k for a k-generic arrangement is V(ann(Ext^{k+1}(F(A),S))), "

BIRS Focussed research group on complex arrangements, Banff, Canada, 6/06.

"Holonomy Lie algebras, Graphic Arrangements, and Tor_i^A(k,k)_i,"

AMS Special Session on Syzygies, San Antonio, TX, 1/06.

"Bigraded algebra and incomplete linear systems on P^1 x P^1",

AMS Special Session on Resolutions, Eugene, OR, 11/05.

"Projective dimension and derivations'',

PIMS workshop on Hyperplane Arrangements, Vancouver, Canada, 8/05.

"Syzygies and toric varieties'',

BASCOLA: Coloquio de Algebra en Buenos Aires, Buenos Aires, Argentina, 8/05.

"Holonomy Lie algebras and the LCS formula for graphic arrangements'',

XVI Coloquio Latinoamericano de Algebra, Colonia, Uruguay, 8/05.

"A spectral sequence stratification of cohomology jump loci''.

BIRS Focussed research group on cohomology and rational homotopy, Banff, Canada, 6/05.

"Commutative and homological methods for arrangements'',

MSRI Program on Hyperplane Arrangements, Berkeley, 4/04.

"Ideals of monomials and ideals of powers of linear forms'',

MFO workshop on commutative algebra and combinatorics, Oberwolfach, 4/04.

"Chen ranks and the Bernstein-Gelfand-Gelfand correspondence'',

Geometry-Combinatorics workshop, Flagstaff, 1/04.

"Linear systems on a special rational surface'',

AMS Special Session on Algebraic Geometry, Boulder, 10/03.

"Castelnuovo-Mumford regularity and line configurations in the projective plane'',

AMS Special Session on Combinatorial Commutative Algebra and Algebraic Geometry, San Francisco, 5/03.

"Hyperplane arrangements, free resolutions, and Bernstein-Gelfand-Gelfand'',

MSRI workshop on Computational Commutative Algebra, Berkeley, 3/03.

"Hyperplane arrangements and free resolutions'',

Contemporary Algebra and Algebraic Geometry conference, Texas Tech University, 11/02.

Symbolic Computational Algebra - Fields Institute special meeting, London, Ontario 7/02.

"Resonance Varieties and free resolutions'',

MFO workshop on Cohomology Jumping Loci, Oberwolfach, 3/02.

"Local complete intersections in P^2 and Koszul syzygies'',

AMS Special Session on Computational Algebraic Geometry, San Diego, 1/02.

Annapolis Algebraic Geometry conference, USNA, 10/01.

"A formula of Solomon-Terao and vector bundles on P^n'',

AMS Special Session on Commutative Algebra, New York, 11/00.

"Cohomology vanishing and a problem in approximation theory'',

AMS Special Session on Algebraic Geometry, Toronto, 9/00.

"Stability and jump loci of a family of bundles on P^2'',

AMS Special Session on Hyperplane Arrangements, New York, 11/00.

Aspects of Algebraic Geometry and Commutative Algebra, Texas A&M, 5/00.

AMS Special Session on Syzygies, Lowell, April 2000.

"Logarithmic p-forms on a locally free arrangement'',

Arrangements in Boston, Boston, June 1999.

"The Chern polynomial of a three arrangement'',

MSRI Workshop on computational methods in algebra and geometry, Berkeley, October 1998.

AMS Special Session on Commutative Algebra, Chicago, September 1998.

"Subalgebras of the Stanley-Reisner ring'',

AMS Special Session on Commutative Algebra, Montreal, September 1997.

"A spectral sequence for splines'',

Conference on Commutative Algebra and Combinatorics, Essen, Germany, June 1997.

MSRI workshop on Geometric Combinatorics, Berkeley, February 1997.

"Homological methods in the theory of splines'',

AMS Special Session on Computational Algebraic Geometry, San Diego, January 1997.

"Local cohomology of bivariate splines'',

Fourth International Symposium on Effective Methods in Algebraic Geometry, Eindhoven, Netherlands, June 1996.

Colloquium talks at Amherst, Auburn, Georgia, Illinois, Navy, Nebraska, New Hampshire, Notre Dame, Rice, Texas A&M, TCU, UC-Riverside, UNC-Charlotte, U. North Texas, U. Tennessee, UT-Arlington, Western Illinois, U. Western Ontario, Virginia Tech, Wisconsin.

Seminar talks at Auburn, Berkeley, Berlin, Brown, Buenos Aires, Chicago, Cornell, Georgia, Harvard, Illinois, Minnesota, MIT, Nebraska, New Hampshire, Northeastern, Notre Dame, Oxford, Purdue, Queens, Texas A&M, TCU, UIUC, UIC, UMass, UC-Riverside, UC-San Diego, UNC-Charlotte, U. North Texas, UT-Austin, U. Western Ontario, Wisconsin.