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55
Stable model categories are categories of modules
 TOPOLOGY
, 2003
"... A stable model category is a setting for homotopy theory where the suspension functor is invertible. The prototypical examples are the category of spectra in the sense of stable homotopy theory and the category of unbounded chain complexes of modules over a ring. In this paper we develop methods for ..."
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Cited by 78 (16 self)
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A stable model category is a setting for homotopy theory where the suspension functor is invertible. The prototypical examples are the category of spectra in the sense of stable homotopy theory and the category of unbounded chain complexes of modules over a ring. In this paper we develop methods for deciding when two stable model categories represent ‘the same homotopy theory’. We show that stable model categories with a single compact generator are equivalent to modules over a ring spectrum. More generally stable model categories with a set of generators are characterized as modules over a ‘ring spectrum with several objects’, i.e., as spectrum valued diagram categories. We also prove a Morita theorem which shows how equivalences between module categories over ring spectra can be realized by smashing with a pair of bimodules. Finally, we characterize stable model categories which represent the derived category of a ring. This is a slight generalization of Rickard’s work on derived equivalent rings. We also include a proof of the model category equivalence of modules over the EilenbergMac Lane spectrum HR and (unbounded) chain complexes of Rmodules for a ring R.
On Gorenstein projective, injective and flat dimensions  a functorial description with applications
, 2004
"... For a large class of rings, including all those encountered in algebraic geometry, we establish the conjectured Moritalike equivalence between the full subcategory of complexes of finite Gorenstein flat dimension and that of complexes of finite Gorenstein injective dimension. This functorial descr ..."
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Cited by 53 (18 self)
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For a large class of rings, including all those encountered in algebraic geometry, we establish the conjectured Moritalike equivalence between the full subcategory of complexes of finite Gorenstein flat dimension and that of complexes of finite Gorenstein injective dimension. This functorial description meets the expectations and delivers a series of new results, which allows us to establish a wellrounded theory for Gorenstein dimensions. For any pair of adjoint functors, C
Ktheory and derived equivalences
 Duke Math. J
"... Abstract. We show that if two rings have equivalent derived categories then they have the same algebraic Ktheory. Similar results are given for Gtheory, and for a large class of abelian categories. Contents ..."
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Cited by 29 (6 self)
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Abstract. We show that if two rings have equivalent derived categories then they have the same algebraic Ktheory. Similar results are given for Gtheory, and for a large class of abelian categories. Contents
Reflexivity and ring homomorphisms of finite flat dimension
 Comm. Algebra
"... Dedicated to the memory of Saunders Mac Lane. Abstract. In this paper we present a systematic study of the reflexivity properties of homologically finite complexes with respect to semidualizing complexes in the setting on nonlocal rings. One primary focus is the descent of these properties over ring ..."
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Cited by 19 (16 self)
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Dedicated to the memory of Saunders Mac Lane. Abstract. In this paper we present a systematic study of the reflexivity properties of homologically finite complexes with respect to semidualizing complexes in the setting on nonlocal rings. One primary focus is the descent of these properties over ring homomorphisms of finite flat dimension, presented in terms of inequalities between the generalized Gdimensions of Foxby, Golod, and Christensen. Most of these results are new even when the ring homomorphism is local. The main tool for these analyses is a nonlocal version of the amplitude inequality of Iversen, Foxby, and Iyengar. We provide numerous examples demonstrating the need for certain hypotheses and the strictness of many inequalities.
Morita theory in abelian, derived and stable model categories, Structured ring spectra
 London Math. Soc. Lecture Note Ser
, 2004
"... These notes are based on lectures given at the Workshop on Structured ring spectra and ..."
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Cited by 19 (0 self)
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These notes are based on lectures given at the Workshop on Structured ring spectra and
From triangulated categories to Lie algebras: A theorem of Peng and Xiao, Trends in representation theory of algebras and related
, 2006
"... In his seminal article [13], Ringel showed how to associate to any finitary ring Λ an associative unital algebra H(Λ), with structure constants encoding information about extensions between finite modules. This generalised the Hall algebra [3, 17], which deals with the ring of padic integers Zp and ..."
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Cited by 16 (1 self)
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In his seminal article [13], Ringel showed how to associate to any finitary ring Λ an associative unital algebra H(Λ), with structure constants encoding information about extensions between finite modules. This generalised the Hall algebra [3, 17], which deals with the ring of padic integers Zp and finite pgroups. In the subsequent article [14] it is shown that if Λ is a representationdirected algebra over a finite field k, then the structure constants are given by evaluating integer polynomials. Using these Hall polynomials as structure constants, one may therefore form the generic RingelHall algebra over Z[T]. Let n(Λ) be the subgroup of H(Λ) generated by the indecomposable modules. If we specialise T ↦ → 1, then Z ⊗ Z[T]n(Λ) becomes a Lie subalgebra of Z ⊗ Z[T]H(Λ). In fact, over the rational numbers, Q ⊗ Z[T] H(Λ) is isomorphic to the universal enveloping algebra of Q ⊗ Z[T] n(Λ). In particular, let Λ be a representationfinite hereditary kalgebra and let g = n − ⊕h⊕n+ be the semisimple complex Lie algebra of the same type as Λ. Then Z ⊗ Z[T]n(Λ) can be identified with the Chevalley Zform of n+, and Z ⊗ Z[T]H(Λ) becomes the Kostant Zform of the universal enveloping algebra U(n+) [15]. For a general finite dimensional hereditary kalgebra Λ one considers the composition algebra, the subalgebra generated by the simple modules. This also has a generic version, constructed as a subalgebra of a direct product over infinitely many finite fields of composition algebras [16]. Green showed in [2] that the generic composition algebra (after twisting the multiplication via the Euler form of the category modΛ) is isomorphic to the quantum group of the same type as Λ. Therefore, we can realise the quantum group of any symmetrisable KacMoody Lie algebra via the module categories of finite dimensional hereditary kalgebras. A natural question is whether it is possible to obtain the full (quantised) enveloping algebra, or at least the full Lie algebra. The latter question was answered by Peng and Xiao in [9] for the affine Lie algebras of type Ã, and in [10] for the
Auslander algebras and initial seeds for cluster algebras
 J. LONDON MATH. SOC
, 2006
"... Let Q be a Dynkin quiver and Π the corresponding set of positive roots. For the preprojective algebra Λ associated to Q we produce a rigid Λmodule IQ with r = Π  pairwise nonisomorphic indecomposable direct summands by pushing the injective modules of the Auslander algebra of kQ to Λ. If N is ..."
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Cited by 15 (4 self)
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Let Q be a Dynkin quiver and Π the corresponding set of positive roots. For the preprojective algebra Λ associated to Q we produce a rigid Λmodule IQ with r = Π  pairwise nonisomorphic indecomposable direct summands by pushing the injective modules of the Auslander algebra of kQ to Λ. If N is a maximal unipotent subgroup of a complex simply connected simple Lie group of type Q, then the coordinate ring C[N] is an upper cluster algebra. We show that the elements of the dual semicanonical basis which correspond to the indecomposable direct summands of IQ coincide with certain generalized minors which form an initial cluster for C[N], and that the corresponding exchange matrix of this cluster can be read from the Gabriel quiver of EndΛ(IQ). Finally, we exploit the fact that the categories of injective modules over Λ and over its covering ˜ Λ are triangulated in order to show several interesting identities in the respective stable module categories.
Isomorphisms Between Left And Right Adjoints
 Theory Appl. Categ
, 2003
"... There are many contexts in algebraic geometry, algebraic topology, and homological algebra where one encounters a functor that has both a left and right adjoint, with the right adjoint being isomorphic to a shift of the left adjoint specified by an appropriate "dualizing object". Typically the le ..."
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Cited by 15 (2 self)
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There are many contexts in algebraic geometry, algebraic topology, and homological algebra where one encounters a functor that has both a left and right adjoint, with the right adjoint being isomorphic to a shift of the left adjoint specified by an appropriate "dualizing object". Typically the left adjoint is well understood while the right adjoint is more mysterious, and the result identifies the right adjoint in familiar terms. We give a categorical discussion of such results. One essential point is to di#erentiate between the classical framework that arises in algebraic geometry and a deceptively similar, but genuinely di#erent, framework that arises in algebraic topology.
Semidualizing modules and the divisor class group
 Illinois J. Math
"... Dedicated to Phillip Griffith on the occasion of his retirement Abstract. Among the finitely generated modules over a Noetherian ring R, the semidualizing modules have been singled out due to their particularly nice duality properties. When R is a normal domain, we exhibit a natural inclusion of the ..."
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Cited by 12 (10 self)
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Dedicated to Phillip Griffith on the occasion of his retirement Abstract. Among the finitely generated modules over a Noetherian ring R, the semidualizing modules have been singled out due to their particularly nice duality properties. When R is a normal domain, we exhibit a natural inclusion of the set of isomorphism classes of semidualizing Rmodules into the divisor class group of R. After a description of the basic properties of this inclusion, it is employed to investigate the structure of the set of isomorphism classes of semidualizing Rmodules. In particular, this set is described completely for determinantal rings over normal domains. 1.