(Algebraic Geometry, Algebra and Number Theory Seminar)

a joint venture of   UNT, UTA and TCU

Date/Time/Room: Fri Nov 21, 2003, at 3:00 pm in PKH 487 at UTA
                          Refreshments will be served at 2:45 pm.
Speaker: Dr. David Jorgensen, Department of Mathematics, UTA

``Nonvanishing Cohomology and Classes of Gorenstein Rings''

Abstract: The main focus of the talk will be recent results of L. Sega and the speaker, which include a counterexample to a conjecture of Auslander as well as refinements on the Gorenstein condition for commutative local rings. These refinements are stated in terms of vanishing homology and cohomology for finitely-generated modules. In particular, the open problem that all higher Ext(M,N) vanish if and only all higher Ext(N,M) vanish for finitely-generated modules M and N over a Gorenstein local ring will be discussed.

  Please mention/email this talk to any interested parties and to your students if you are teaching an advanced undergraduate algebra class or a graduate algebra class.

DRIVING DIRECTIONS (NOTE: owing to construction on the UTA campus, the directions have been revised!)

If you are travelling from out of town, then a map of UTA may be found at Note that PKH is the triangular building in the central-campus region of the map. Click on central campus to zoom in, and PKH is in the SE corner of that map, next to the "garage" & is on Nedderman Drive between College St & West St. Parking is available in the nearby (East and SE of PKH) parking lots with a UTA permit (but many people park there late on Fridays with no permit and are not caught). Visitor (free), & metered, parking is available by Davis Hall (marked DH in South West part of map). A parking garage (expensive) is nextdoor to PKH (use West St to get to it). Note that if heading south on Cooper, then no left turn is allowed to Nedderman Drive. Recommended route from UNT: eventually head south on Hwy 360 (or Industrial Blvd = Collins) West on Abram, south on Pecan, West on 4th, South on West St. Then use map. From TCU: east on I30, exit Cooper, South on Cooper (but there is currently construction on Cooper and so the possibility of heavy delays, so you might prefer to use Fielder, heading South to W Mitchell, East on W Mitchell to Cooper), then use map. (Note that Nedderman Drive between West St and Pecan St is closed.) From anywhere else: good luck! Note that PKH 487 is on the 4th floor of PKH; turn right out of elevator on 4th floor.

Questions, etc on arrangements/directions? Contact Michaela Vancliff. Please notify us if coming from out of town, since, if you are a little late, we will delay the start of the talk for you.