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Recent Submissions

  • The Isomorphism problem for incidence rings 

    Abrams, Gene; Haefner, Jeremy; Del Rio, Angel (University of California, 1999)
    Let P and P’ be finite preordered sets, and let R be a ring for which the number of nonzero summands in a direct decomposition of the regular module RR is bounded. We show that if the incidence rings I(P;R) and I(P’;R) ...
  • Actions of picard groups on graded rings 

    Haefner, Jeremy; Del Rio, Angel (Elsevier, 1999)
    No abstract found.
  • Strongly graded hereditary orders 

    Haefner, Jeremy; Pappacena, Christopher (2001-08-28)
    Let R be a Dedekind domain with global quotient field K. The purpose of this note is to provide a characterization of when a strongly graded R-order with semiprime 1-component is hereditary. This generalizes earlier work ...
  • Automorphisms of tiled orders 

    Haefner, Jeremy; Pappacena, Christopher (Elsevier, 2002)
    Let Λ be a tiled R-order. We give a description of AutR(Λ) as the semidirect product of Inn(Λ) and a certain subgroup of Aut(Q(Λ)), where Q(Λ) is the link graph of Λ. Additionally, we give criteria for determining when ...
  • The Globalization problem for inner automorphisms and Skolem-Noether theorems 

    Haefner, Jeremy; Del Rio, Angel (World Science, 2003-07)
    We investigate the circumstances under which an inner automorphism of a ring with local units can be built from “local” information. Specifically, we consider three natural “inner” type properties for an automorphism of ...
  • Hereditary crossed products 

    Haefner, Jeremy; Janusz, Gerald (American Mathmatical Society, 2000-03-27)
    We characterize when a crossed product order over a maximal order in a central simple algebra by a finite group is hereditary. We need only concentrate on the cases when the group acts as inner automorphisms and when ...
  • On when a graded ring is graded equivalent to a crossed product 

    Haefner, Jeremy (American Mathmatical Society, 1996-04)
    Let R be a ring graded by a group G. We are concerned with describing those G-graded rings that are graded equivalent to G-crossed products. We give necessary and sufficient conditions for when a strongly graded ring ...
  • Isomorphisms of row and column finite matrix rings 

    Haefner, Jeremy; Del Rio, A.; Simon, J. (American Mathmatical Society, 1997-06)
    This paper investigates the ring-theoretic similarities and the cate- gorical dissimilarities between the ring RFM(R) of row finite matrices and the ring RCFM(R) of row and column finite matrices. For example, we prove ...
  • Graded equivalence theory with applications 

    Haefner, Jeremy (Elsevier, 1995-03-01)
    We develop the foundations for graded equivalence theory and apply them to investigate properties such as primeness, finite representation type, and vertex theory of graded rings. The key fact that we prove is that, for ...
  • Mind over matter: Transforming course management systems into effective learning environments 

    Carmean, Colleen; Haefner, Jeremy (EDUCAUSE, 2002-12)
    Integrating best practices for "deeper learning" with the robust tools provided by course management systems creates an incredibly effective, engaging, and student-centered learning environment.
  • Local orders whose lattices are direct sums of ideals 

    Haefner, Jeremy (American Mathematical Society, 1990-10)
    Let R be a complete local Dedekind domain with quotient field K and let A be a local R-order in a separable K-algebra. This paper classifies those orders A such that every indecomposable R-torsionfree A-module is isomorphic ...
  • Approximating rings with local units via automorphisms 

    Abrams, G.; Haefner, Jeremy; del Rio, A. (Springer Verlag, 1999-02)
    For a ring A with local units we investigate unital overrings T of A, and compare the automorphism groups Aut(A) and Aut(T ).