Perfectoid Diamonds and N-Awareness. a Meta-Model of Subjective Experience
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COVERING THEORY for LINEAR CATEGORIES with APPLICATION to DERIVED CATEGORIES Introduction the Covering Technique Has Been Playin
COVERING THEORY FOR LINEAR CATEGORIES WITH APPLICATION TO DERIVED CATEGORIES RAYMUNDO BAUTISTA AND SHIPING LIU Abstract. We extend the Galois covering theory introduced by Bongartz- Gabriel for skeletal linear categories to general linear categories. We show that a Galois covering between Krull-Schmidt categories preserves irreducible morphisms and almost splits sequences. Specializing to derived categories, we study when a Galois covering between locally bounded linear categories induces a Galois covering between the bounded derived categories of finite dimensional modules. As an application, we show that each locally bounded linear category with radical squared zero admits a gradable Galois covering, which induces a Galois covering between the bounded derived categories of finite dimensional modules, and a Galois covering between the Auslander-Reiten quivers of these bounded derived categories. In a future paper, this will enable us to obtain a complete description of the bounded derived category of finite dimensional modules over a finite dimensional algebra with radical squared zero. Introduction The covering technique has been playing an important role in the representation theory of finite dimensional algebras; see, for example, [6, 8, 9, 16]. In this connec- tion, algebras are regarded as locally bounded linear categories; see [6]. To each Galois covering between such categories, Bongartz-Gabriel associated a push-down functor between their module categories, which induces a Galois covering between the Auslander-Reiten quivers in the locally representation-finite case; see [6, 8]. This technique was extended later by Asashiba by studying the induced push-down functor between the bounded homotopy categories of finitely generated projective modules; see [1]. -
THE SIX OPERATIONS for SHEAVES on ARTIN STACKS II: ADIC COEFFICIENTS ? by YVES LASZLO and MARTIN OLSSON
THE SIX OPERATIONS FOR SHEAVES ON ARTIN STACKS II: ADIC COEFFICIENTS ? by YVES LASZLO and MARTIN OLSSON ABSTRACT In this paper we develop a theory of Grothendieck’s six operations for adic constructible sheaves on Artin stacks continuing the study of the finite coefficients case in [14]. 1. Introduction In this paper we continue the study of Grothendieck’s six operations for sheaves on Artin stacks begun in [14]. Our aim in this paper is to extend the theory of finite coefficients of loc. cit. to a theory for adic sheaves. In a subsequent paper [15] we will use this theory to study perverse sheaves on Artin stacks. Throughout we work over an affine excellent finite-dimensional scheme S. Let ` be a prime invertible in S, and such that for any S-scheme X of finite type we have cd`(X) < ∞ (see [14], 1.0.1 for more discussion of this assumption). In what follows, all stacks considered will be algebraic locally of finite type over S. Let Λ be a complete discrete valuation ring with maximal ideal m and n with residue characteristic `, and for every n let Λn denote the quotient Λ/m so that Λ = lim Λ . We then define for any stack X a triangulated category ←− n Dc(X ,Λ) which we call the derived category of constructible Λ–modules on X (of course as in the classical case this is abusive terminology). The cat- egory Dc(X ,Λ) is obtained from the derived category of projective systems {Fn} of Λn–modules by localizing along the full subcategory of complexes whose cohomology sheaves are AR-null (see 2.1 for the meaning of this). -
Infinity-Tilting Theory
∞-TILTING THEORY LEONID POSITSELSKI AND JAN SˇTOVˇ ´ICEKˇ Abstract. We define the notion of an infinitely generated tilting object of infi- nite homological dimension in an abelian category. A one-to-one correspondence between ∞-tilting objects in complete, cocomplete abelian categories with an injec- tive cogenerator and ∞-cotilting objects in complete, cocomplete abelian categories with a projective generator is constructed. We also introduce ∞-tilting pairs, con- sisting of an ∞-tilting object and its ∞-tilting class, and obtain a bijective corre- spondence between ∞-tilting and ∞-cotilting pairs. Finally, we discuss the related derived equivalences and t-structures. Contents Introduction 1 1. The Tilted and Cotilted Abelian Categories 4 2. ∞-Tilting-Cotilting Correspondence 7 3. ∞-Tilting and ∞-Cotilting Pairs 13 4. ∞-Tilting-Cotilting Derived Equivalences 17 5. ∞-Tilting and ∞-Cotilting t-Structures 20 6. Examples 25 References 32 Introduction The phrase ‘tilting theory’ is often used to refer to a well-developed general ma- chinery for producing equivalences between triangulated categories (see [3] for an introduction, history and applications). Such equivalences are often represented by a arXiv:1711.06169v3 [math.CT] 13 Aug 2019 distinguished object, a so-called tilting object, and it is crucial to most of the theory that such a tilting object is homologically small. If A is an abelian category with exact coproducts (e.g. a category of modules over a ring or sheaves on a topological space) and T is a tilting object, the smallness typically translates at least to the assumptions that T is finitely generated and of finite projective dimension. In this paper we introduce and systematically develop ∞-tilting theory, where all homological smallness assumptions are dropped. -
I. Overview of Activities, April, 2005-March, 2006 …
MATHEMATICAL SCIENCES RESEARCH INSTITUTE ANNUAL REPORT FOR 2005-2006 I. Overview of Activities, April, 2005-March, 2006 …......……………………. 2 Innovations ………………………………………………………..... 2 Scientific Highlights …..…………………………………………… 4 MSRI Experiences ….……………………………………………… 6 II. Programs …………………………………………………………………….. 13 III. Workshops ……………………………………………………………………. 17 IV. Postdoctoral Fellows …………………………………………………………. 19 Papers by Postdoctoral Fellows …………………………………… 21 V. Mathematics Education and Awareness …...………………………………. 23 VI. Industrial Participation ...…………………………………………………… 26 VII. Future Programs …………………………………………………………….. 28 VIII. Collaborations ………………………………………………………………… 30 IX. Papers Reported by Members ………………………………………………. 35 X. Appendix - Final Reports ……………………………………………………. 45 Programs Workshops Summer Graduate Workshops MSRI Network Conferences MATHEMATICAL SCIENCES RESEARCH INSTITUTE ANNUAL REPORT FOR 2005-2006 I. Overview of Activities, April, 2005-March, 2006 This annual report covers MSRI projects and activities that have been concluded since the submission of the last report in May, 2005. This includes the Spring, 2005 semester programs, the 2005 summer graduate workshops, the Fall, 2005 programs and the January and February workshops of Spring, 2006. This report does not contain fiscal or demographic data. Those data will be submitted in the Fall, 2006 final report covering the completed fiscal 2006 year, based on audited financial reports. This report begins with a discussion of MSRI innovations undertaken this year, followed by highlights -
TILTING up ITERATED TILTED ALGEBRAS 1. Introduction Throughout This Paper, We Let K Denote a Fixed Algebraically Closed Field. B
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 128, Number 8, Pages 2223{2232 S 0002-9939(99)05230-2 Article electronically published on November 29, 1999 TILTING UP ITERATED TILTED ALGEBRAS IBRAHIM ASSEM, DIETER HAPPEL, AND SONIA TREPODE (Communicated by Ken Goodearl) Abstract. We show that, if A is a representation-finite iterated tilted algebra of euclidean type Q, then there exist a sequence of algebras A = A0;A1;A2;:::; (i) (i) Am, and a sequence of modules T ,where0≤ i<m,suchthateachT is Ai Ai (i) an APR-tilting Ai-module, or an APR-cotilting Ai-module, End T = Ai+1 Ai and Am is tilted representation-finite. 1. Introduction Throughout this paper, we let k denote a fixed algebraically closed field. By algebra is always meant a finite dimensional associative k-algebra with an identity, which we assume moreover to be basic and connected, and by module is meant a finitely generated right A-module. Tilting theory is by now an established tool in the representation theory of algebras. In particular, the classes of tilted and iterated tilted algebras, introduced by means of the tilting process, were very useful, for instance, in the classification of the self-injective algebras of polynomial growth (see [1], [7], [11]). We recall their definition. Let Q be a finite, connected quiver without oriented cycles and let kQ denote the path algebra of Q.AnalgebraA is said to be iterated tilted of type Q if there exists a going-up tilting series from A to kQ, that is, a sequence of algebras A = A0;A1;:::;Am = kQ and a sequence of tilting modules T (i),where0≤ i<m, such that End T (i) = A and each T (i) Ai Ai i+1 Ai is separating, that is, such that each indecomposable Ai-module M satisfies either (i) 1 (i) HomAi (T ;M)=0orExtAi (T ;M) = 0 (see [2]). -
Spaces Determined by Point-Countable Covers
Pacific Journal of Mathematics SPACES DETERMINED BY POINT-COUNTABLE COVERS GARY FRED GRUENHAGE,ERNEST A. MICHAEL AND YOSHIO TANAKA Vol. 113, No. 2 April 1984 PACIFIC JOURNAL OF MATHEMATICS Vol. 113, No. 2,1984 SPACES DETERMINED BY POINT-COUNTABLE COVERS G. GRUENHAGE, E. MICHAEL AND Y. TANAKA Recall that a collection 9 of subsets of X is point-countable if every x G X is in at most countably many ?Gf. Such collections have been studied from several points of view. First, in characterizing various kinds of j-images of metric spaces, second, to construct conditions which imply that compact spaces and some of their generalizations are metrizable, and finally, in the context of meta-Lindelόf spaces. This paper will make some contributions to all of these areas. 1. Introduction. A space1 X is determined by a cover £P, or 9 determines X,2 if U C X is open (closed) in X if and only if U Π P is relatively open (relatively closed) in P for every P E <•?. (For example, X is determined by <$ if <$ is locally finite or if {P°: P E <3>} covers X.) We will explore this notion in the context of point-countable covers. Within the class of λ -spaces, spaces determined by point-countable covers turn out to be related to spaces having a point-countable Λ -net- work. Recall that a cover ζP of X is a k-network for X if, whenever K C U with K compact and U open in X9 then K C U φ C U for some finite ^C^. -
Generalized Tilting Theory in Functor Categories
Table of content Motivation and Introduction Main results Applications Generalized tilting theory in functor categories Xi Tang April 25, 2019 logo Table of content Motivation and Introduction Main results Applications Table of content 1 Motivation and Introduction 2 Main results Equivalences induced by T A cotorsion pair 3 Applications An isomorphism of Grothendieck groups An abelian model structure A t-structure induced by T logo Table of content Motivation and Introduction Main results Applications References S. Bazzoni, The t-structure induced by an n- tilting module, Trans. Amer. Math. Soc. (to ap- pear). R. Mart´ınez-Villa and M. Ortiz-Morales, Tilting theory and functor categories I. Classical tilt- ing, Appl. Categ. Struct. 22 (2014), 595–646. R. Mart´ınez-Villa and M. Ortiz-Morales, Tilting theory and functor categories II. Generalized tilting, Appl. Categ. Struct. 21 (2013), 311– logo 348. Table of content Motivation and Introduction Main results Applications Motivation K algebraically closed field Λ finite dimensional K-algebra TΛ tilting module Γ := End(T)op Brenner-Butler Tilting Theorem The following statements hold. (1) (T (T); F(T)) is a torsion theory, where 1 T (T) := fM 2 mod Λ j ExtΛ(T; M) = 0g; logo F(T) := fM 2 mod Λ j HomΛ(T; M) = 0g: Table of content Motivation and Introduction Main results Applications Motivation (2) (X (T); Y(T)) is a torsion theory, where X (T) := fN 2 mod Γ j N ⊗Γ T = 0g; Γ Y(T) := fN 2 mod Γ j Tor1 (N; T) = 0g. (3) There are two category equivalences: T (T) F(T) g 7 s s w ' X (T) Y(T): logo Table of content Motivation and Introduction Main results Applications R associative ring TR n-tilting module S := End(T)op Miyashita Theorem There are category equivalences: e ExtR(T;−) n / n KE (TR) KT (ST); where e o s e S Tore (−;T) n i KEe (TR) := fM j ExtR(T; M) = 0; 0 6 i 6= e 6 ng; n S logo KTe (ST) := fN j Tori (N; T) = 0; 0 6 i 6= e 6 ng. -
On Compact-Covering and Sequence-Covering Images of Metric Spaces
MATEMATIQKI VESNIK originalni nauqni rad 64, 2 (2012), 97–107 research paper June 2012 ON COMPACT-COVERING AND SEQUENCE-COVERING IMAGES OF METRIC SPACES Jing Zhang Abstract. In this paper we study the characterizations of compact-covering and 1-sequence- covering (resp. 2-sequence-covering) images of metric spaces and give a positive answer to the following question: How to characterize first countable spaces whose each compact subset is metrizable by certain images of metric spaces? 1. Introduction To find internal characterizations of certain images of metric spaces is one of the central problems in General Topology. In 1973, E. Michael and K. Nagami [16] obtained a characterization of compact-covering and open images of metric spaces. It is well known that the compact-covering and open images of metric spaces are the first countable spaces whose each compact subset is metrizable. However, its inverse does not hold [16]. For the first countable spaces whose each compact subset is metrizable, how to characterize them by certain images of metric spaces? The sequence-covering maps play an important role on mapping theory about metric spaces [6, 9]. In this paper, we give the characterization of a compact- covering and 1-sequence-covering (resp. 2-sequence-covering) image of a metric space, and positively answer the question posed by S. Lin in [11, Question 2.6.5]. All spaces considered here are T2 and all maps are continuous and onto. The letter N is the set of all positive natural numbers. Readers may refer to [10] for unstated definition and terminology. 2. -
ALL TILTING MODULES ARE of FINITE TYPE 1. Introduction in The
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 135, Number 12, December 2007, Pages 3771–3781 S 0002-9939(07)08911-3 Article electronically published on August 30, 2007 ALL TILTING MODULES ARE OF FINITE TYPE SILVANA BAZZONI AND JAN SˇTOVˇ ´ICEKˇ (Communicated by Martin Lorenz) Abstract. We prove that any infinitely generated tilting module is of finite type, namely that its associated tilting class is the Ext-orthogonal of a set of modules possessing a projective resolution consisting of finitely generated projective modules. 1. Introduction In the early eighties Brenner and Butler in [9] and Happel and Ringel in [18] gen- eralized the classical Morita equivalence induced by a progenerator by introducing the notion of a tilting module over a finite-dimensional Artin algebra. In order to obtain equivalences between subcategories of the module category, tilting modules were assumed to be finitely generated and moreover of projective dimension at most one. Later, Miyashita [20] considered tilting modules of finite projective dimension and studied the equivalences induced by them. Colby and Fuller in [10] extended the setting to arbitrary rings, but in all the above-mentioned papers the tilting modules were always assumed to be finitely generated. The notion of infinitely generated tilting modules over arbitrary rings was introduced by Colpi and Trlifaj in [11] for the one-dimensional case and by Angeleri-H¨ugel and Coelho in [1] in the general case of finite projective dimension. One of the advantages in dealing with infinitely generated tilting modules is evident in connection with the good approximation theory that they induce and which we are going to illustrate (cf. -
Triangulated Categories of Motives Over Fs Log Schemes
Triangulated Categories of Motives over fs Log Schemes by Doosung Park A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Mathematics in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Martin Olsson, Chair Professor Kam-Biu Luk Professor Constantin Teleman Professor Xinyi Yuan Fall 2016 Triangulated Categories of Motives over fs Log Schemes Copyright 2016 by Doosung Park Abstract Triangulated Categories of Motives over fs Log Schemes by Doosung Park Doctor of Philosophy in Mathematics University of California, Berkeley Professor Martin Olsson, Chair In this thesis, we construct triangulated categories of motives over fs log schemes with rational coefficients and formulate its six operations formalism. For these, we introduce pw- topology and log-weak equivalences to study the homotopy equivalences of fs log schemes. We also introduce equivariant cd-structures to deal with descent theory of motives more systematically. 1 Contents Contents i Introduction v 1 Construction 1 1.1 Premotivic categories . .1 1.2 Equivariant cd-structures . .4 1.3 Descents . 13 1.4 Compactness . 16 1.5 Localizing subcategories . 17 1.6 Bousfield localization . 22 1.7 log-localization . 27 2 Properties of premotivic triangulated categories 33 2.1 Elementary properties . 34 2.2 Localization property . 35 2.3 Support property . 36 2.4 Homotopy properties . 39 2.5 Purity . 40 2.6 Base change property . 42 2.7 Projection formula . 45 2.8 Orientation . 46 2.9 Log motivic categories . 46 3 Some results on log geometry and motives 48 3.1 Charts of log smooth morphisms . -
Τ-Tilting Theory – an Introduction
τ-TILTING THEORY – AN INTRODUCTION HIPOLITO TREFFINGER 1. Introduction The term τ-tilting theory was coined by Adachi, Iyama and Reiten in [3] a paper having this title that first appeared in the arXiv in 2012 and that was published in 2014. In this paper, the authors combined with a fresh approach to the the study of two classical branches of representation theory of finite dimensional algebras, namely tilting theory and Auslander-Reiten theory. The combination of these two subjects is clearly reflected in the name of this novel theory, where the greek letter τ represents the Auslander-Reiten translation in the module category of an algebra while the reference to tilting theory is obvious. In these notes we give a small introduction to τ-tilting theory from the representation the- oretic perspective, making special emphasis in the close relation between τ-tilting theory and torsion theories. Clearly, this notes do not represent a complete survey on the topic since several important aspects of the theory are not covered in detail or even mentioned. For instance, in this notes we do not cover the explicit between τ-tilting theory with cluster theory, stability conditions, or exceptional sequences, just to name a few. These notes are organised as follows. In Section 2 we give a short historical account of the developments in representation theory that lead to the introduction of τ-tilting theory, hoping that this will help placing τ-tilting theory in the more general framework of representation theory. Then, in Section 3 we start giving the material that is covered in the lectures by giving the definition of our main objects of study: τ-rigid and τ-tilting modules and pairs. -
Grothendieck and the Six Operations
The Fifth International Conference on History of Modern Mathematics Xi’an, China August 18–24, 2019 Grothendieck and the six operations Luc Illusie Université Paris-Sud Plan 1. Serre’s duality theorem 2. Derived categories: Grothendieck’s revolution 3. The f ! functor: duality in the coherent setting 4. Duality in étale cohomology and the six operations 5. Further developments 1. Serre’s duality theorem Theorem 1 (ICM Amsterdam, 1954) k algebraically closed, X =k smooth, projective, irreducible, of dimension m, _ V a vector bundle on X , V = Hom(V ; OX ), i i 1 Ω := Λ ΩX =k . Then: m m (a) dimk H (X ; Ω ) = 1; (b) For all q 2 Z, the pairing Hq(X ; V ) ⊗ Hm−q(X ; V _ ⊗ Ωm) ! Hm(X ; Ωm)(!∼ k) is perfect. Remarks (a) Serre had previously proved (FAC) that, for any coherent sheaf q q F on X , and all q, dimk H (X ; F) < 1 and H (X ; F) = 0 for q > m. (b) Serre doesn’t exhibit a distinguished basis of Hm(X ; Ωm). Proof by induction on m, his vanishing theorems on Hq(X ; F(n)) for q > 0 and n large play a key role. Construction of a distinguished basis crucial in further work by Grothendieck et al. (c) Serre proved analogue for X =C smooth, compact analytic, V a vector bundle on X (Comm. Helv., 1955). Quite different techniques. Th. 1 revisited by Grothendieck: 1955-56, Sém. Bourbaki 149, May 1957 X =k smooth, projective, irreducible, dimension m as above. Theorem 2 (Grothendieck, loc. cit., Th.