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Congruences Between Derivatives of Geometric L-Functions
1 Congruences between Derivatives of Geometric L-Functions David Burns with an appendix by David Burns, King Fai Lai and Ki-Seng Tan Abstract. We prove a natural equivariant re¯nement of a theorem of Licht- enbaum describing the leading terms of Zeta functions of curves over ¯nite ¯elds in terms of Weil-¶etalecohomology. We then use this result to prove the validity of Chinburg's (3)-Conjecture for all abelian extensions of global function ¯elds, to prove natural re¯nements and generalisations of the re- ¯ned Stark conjectures formulated by, amongst others, Gross, Tate, Rubin and Popescu, to prove a variety of explicit restrictions on the Galois module structure of unit groups and divisor class groups and to describe explicitly the Fitting ideals of certain Weil-¶etalecohomology groups. In an appendix coau- thored with K. F. Lai and K-S. Tan we also show that the main conjectures of geometric Iwasawa theory can be proved without using either crystalline cohomology or Drinfeld modules. 1991 Mathematics Subject Classi¯cation: Primary 11G40; Secondary 11R65; 19A31; 19B28. Keywords and Phrases: Geometric L-functions, leading terms, congruences, Iwasawa theory 2 David Burns 1. Introduction The main result of the present article is the following Theorem 1.1. The central conjecture of [6] is valid for all global function ¯elds. (For a more explicit statement of this result see Theorem 3.1.) Theorem 1.1 is a natural equivariant re¯nement of the leading term formula proved by Lichtenbaum in [27] and also implies an extensive new family of integral congruence relations between the leading terms of L-functions associated to abelian characters of global functions ¯elds (see Remark 3.2). -
Op → Sset in Simplicial Sets, Or Equivalently a Functor X : ∆Op × ∆Op → Set
Contents 21 Bisimplicial sets 1 22 Homotopy colimits and limits (revisited) 10 23 Applications, Quillen’s Theorem B 23 21 Bisimplicial sets A bisimplicial set X is a simplicial object X : Dop ! sSet in simplicial sets, or equivalently a functor X : Dop × Dop ! Set: I write Xm;n = X(m;n) for the set of bisimplices in bidgree (m;n) and Xm = Xm;∗ for the vertical simplicial set in horiz. degree m. Morphisms X ! Y of bisimplicial sets are natural transformations. s2Set is the category of bisimplicial sets. Examples: 1) Dp;q is the contravariant representable functor Dp;q = hom( ;(p;q)) 1 on D × D. p;q G q Dm = D : m!p p;q The maps D ! X classify bisimplices in Xp;q. The bisimplex category (D × D)=X has the bisim- plices of X as objects, with morphisms the inci- dence relations Dp;q ' 7 X Dr;s 2) Suppose K and L are simplicial sets. The bisimplicial set Kט L has bisimplices (Kט L)p;q = Kp × Lq: The object Kט L is the external product of K and L. There is a natural isomorphism Dp;q =∼ Dpט Dq: 3) Suppose I is a small category and that X : I ! sSet is an I-diagram in simplicial sets. Recall (Lecture 04) that there is a bisimplicial set −−−!holim IX (“the” homotopy colimit) with vertical sim- 2 plicial sets G X(i0) i0→···→in in horizontal degrees n. The transformation X ! ∗ induces a bisimplicial set map G G p : X(i0) ! ∗ = BIn; i0→···→in i0→···→in where the set BIn has been identified with the dis- crete simplicial set K(BIn;0) in each horizontal de- gree. -
Quasi-Categories Vs Simplicial Categories
Quasi-categories vs Simplicial categories Andr´eJoyal January 07 2007 Abstract We show that the coherent nerve functor from simplicial categories to simplicial sets is the right adjoint in a Quillen equivalence between the model category for simplicial categories and the model category for quasi-categories. Introduction A quasi-category is a simplicial set which satisfies a set of conditions introduced by Boardman and Vogt in their work on homotopy invariant algebraic structures [BV]. A quasi-category is often called a weak Kan complex in the literature. The category of simplicial sets S admits a Quillen model structure in which the cofibrations are the monomorphisms and the fibrant objects are the quasi- categories [J2]. We call it the model structure for quasi-categories. The resulting model category is Quillen equivalent to the model category for complete Segal spaces and also to the model category for Segal categories [JT2]. The goal of this paper is to show that it is also Quillen equivalent to the model category for simplicial categories via the coherent nerve functor of Cordier. We recall that a simplicial category is a category enriched over the category of simplicial sets S. To every simplicial category X we can associate a category X0 enriched over the homotopy category of simplicial sets Ho(S). A simplicial functor f : X → Y is called a Dwyer-Kan equivalence if the functor f 0 : X0 → Y 0 is an equivalence of Ho(S)-categories. It was proved by Bergner, that the category of (small) simplicial categories SCat admits a Quillen model structure in which the weak equivalences are the Dwyer-Kan equivalences [B1]. -
Lecture Notes on Simplicial Homotopy Theory
Lectures on Homotopy Theory The links below are to pdf files, which comprise my lecture notes for a first course on Homotopy Theory. I last gave this course at the University of Western Ontario during the Winter term of 2018. The course material is widely applicable, in fields including Topology, Geometry, Number Theory, Mathematical Pysics, and some forms of data analysis. This collection of files is the basic source material for the course, and this page is an outline of the course contents. In practice, some of this is elective - I usually don't get much beyond proving the Hurewicz Theorem in classroom lectures. Also, despite the titles, each of the files covers much more material than one can usually present in a single lecture. More detail on topics covered here can be found in the Goerss-Jardine book Simplicial Homotopy Theory, which appears in the References. It would be quite helpful for a student to have a background in basic Algebraic Topology and/or Homological Algebra prior to working through this course. J.F. Jardine Office: Middlesex College 118 Phone: 519-661-2111 x86512 E-mail: [email protected] Homotopy theories Lecture 01: Homological algebra Section 1: Chain complexes Section 2: Ordinary chain complexes Section 3: Closed model categories Lecture 02: Spaces Section 4: Spaces and homotopy groups Section 5: Serre fibrations and a model structure for spaces Lecture 03: Homotopical algebra Section 6: Example: Chain homotopy Section 7: Homotopical algebra Section 8: The homotopy category Lecture 04: Simplicial sets Section 9: -
A Simplicial Set Is a Functor X : a Op → Set, Ie. a Contravariant Set-Valued
Contents 9 Simplicial sets 1 10 The simplex category and realization 10 11 Model structure for simplicial sets 15 9 Simplicial sets A simplicial set is a functor X : Dop ! Set; ie. a contravariant set-valued functor defined on the ordinal number category D. One usually writes n 7! Xn. Xn is the set of n-simplices of X. A simplicial map f : X ! Y is a natural transfor- mation of such functors. The simplicial sets and simplicial maps form the category of simplicial sets, denoted by sSet — one also sees the notation S for this category. If A is some category, then a simplicial object in A is a functor A : Dop ! A : Maps between simplicial objects are natural trans- formations. 1 The simplicial objects in A and their morphisms form a category sA . Examples: 1) sGr = simplicial groups. 2) sAb = simplicial abelian groups. 3) s(R − Mod) = simplicial R-modules. 4) s(sSet) = s2Set is the category of bisimplicial sets. Simplicial objects are everywhere. Examples of simplicial sets: 1) We’ve already met the singular set S(X) for a topological space X, in Section 4. S(X) is defined by the cosimplicial space (covari- ant functor) n 7! jDnj, by n S(X)n = hom(jD j;X): q : m ! n defines a function ∗ n q m S(X)n = hom(jD j;X) −! hom(jD j;X) = S(X)m by precomposition with the map q : jDmj ! jDmj. The assignment X 7! S(X) defines a covariant func- tor S : CGWH ! sSet; called the singular functor. -
On the Geometric Realization of Dendroidal Sets
Fabio Trova On the Geometric Realization of Dendroidal Sets Thesis advisor: Prof. Ieke Moerdijk Leiden University MASTER ALGANT University of Padova Et tu ouvriras parfois ta fenˆetre, comme ¸ca,pour le plaisir. Et tes amis seront bien ´etonn´esde te voir rire en regardant le ciel. Alors tu leur diras: “Oui, les ´etoiles,¸came fait toujours rire!” Et ils te croiront fou. Je t’aurai jou´eun bien vilain tour. A Irene, Lorenzo e Paolo a chi ha fatto della propria vita poesia a chi della poesia ha fatto la propria vita Contents Introduction vii Motivations and main contributions........................... vii 1 Category Theory1 1.1 Categories, functors, natural transformations...................1 1.2 Adjoint functors, limits, colimits..........................4 1.3 Monads........................................7 1.4 More on categories of functors............................ 10 1.5 Monoidal Categories................................. 13 2 Simplicial Sets 19 2.1 The Simplicial Category ∆ .............................. 19 2.2 The category SSet of Simplicial Sets........................ 21 2.3 Geometric Realization................................ 23 2.4 Classifying Spaces.................................. 28 3 Multicategory Theory 29 3.1 Trees.......................................... 29 3.2 Planar Multicategories................................ 31 3.3 Symmetric multicategories.............................. 34 3.4 (co)completeness of Multicat ............................. 37 3.5 Closed monoidal structure in Multicat ....................... 40 4 Dendroidal Sets 43 4.1 The dendroidal category Ω .............................. 43 4.1.1 Algebraic definition of Ω ........................... 44 4.1.2 Operadic definition of Ω ........................... 45 4.1.3 Equivalence of the definitions........................ 46 4.1.4 Faces and degeneracies............................ 48 4.2 The category dSet of Dendroidal Sets........................ 52 4.3 Nerve of a Multicategory............................... 55 4.4 Closed Monoidal structure on dSet ........................ -
Generic Programming with Adjunctions
Generic Programming with Adjunctions Ralf Hinze Department of Computer Science, University of Oxford Wolfson Building, Parks Road, Oxford, OX1 3QD, England [email protected] http://www.cs.ox.ac.uk/ralf.hinze/ Abstract. Adjunctions are among the most important constructions in mathematics. These lecture notes show they are also highly relevant to datatype-generic programming. First, every fundamental datatype| sums, products, function types, recursive types|arises out of an adjunc- tion. The defining properties of an adjunction give rise to well-known laws of the algebra of programming. Second, adjunctions are instrumental in unifying and generalising recursion schemes. We discuss a multitude of basic adjunctions and show that they are directly relevant to program- ming and to reasoning about programs. 1 Introduction Haskell programmers have embraced functors [1], natural transformations [2], monads [3], monoidal functors [4] and, perhaps to a lesser extent, initial alge- bras [5] and final coalgebras [6]. It is time for them to turn their attention to adjunctions. The notion of an adjunction was introduced by Daniel Kan in 1958 [7]. Very briefly, the functors L and R are adjoint if arrows of type L A → B are in one-to- one correspondence to arrows of type A → R B and if the bijection is furthermore natural in A and B. Adjunctions have proved to be one of the most important ideas in category theory, predominantly due to their ubiquity. Many mathemat- ical constructions turn out to be adjoint functors that form adjunctions, with Mac Lane [8, p.vii] famously saying, \Adjoint functors arise everywhere." The purpose of these lecture notes is to show that the notion of an adjunc- tion is also highly relevant to programming, in particular, to datatype-generic programming. -
The Multitopic Ω–Category of All Multitopic Ω–Categories by M. Makkai (Mcgill University) September 2, 1999; Corrected: June 5, 2004
The multitopic ω–category of all multitopic ω–categories by M. Makkai (McGill University) September 2, 1999; corrected: June 5, 2004 Introduction. Despite its considerable length, this paper is only an announcement. It gives two definitions: that of "multitopic ω-category", and that of "the (large) multitopic set of all (small) multitopic ω-categories". It also announces the theorem that the latter is a multitopic ω-category. The work has two direct sources. One is the paper [H/M/P] in which, among others, the concept of "multitopic set" was introduced. The other is the author's work on FOLDS, first order logic with dependent sorts. The latter was reported on in [M2]. A detailed account of the work on FOLDS is in [M3]. For the understanding of the present paper, what is contained in [M2] suffices. In fact, section 1 of this paper gives the definitions of all that's needed in this paper; so, probably, there won't be even a need to consult [M2]. The concept of multitopic set, the main contribution of [H/M/P], was, in turn, inspired by the work of J. Baez and J. Dolan [B/D]. Multitopic sets are a variant of opetopic sets of loc. cit. The name "multitopic set" refers to multicategories, a concept originally due to J. Lambek [L], and given an only moderately generalized formulation in [H/M/P]. The earlier "opetopic set" is based on a concept of operad; see [B/D]. I should say that the exact relationship of the two concepts ("multitopic set" and "opetopic set") is still not clarified. -
Ends and Coends
THIS IS THE (CO)END, MY ONLY (CO)FRIEND FOSCO LOREGIAN† Abstract. The present note is a recollection of the most striking and use- ful applications of co/end calculus. We put a considerable effort in making arguments and constructions rather explicit: after having given a series of preliminary definitions, we characterize co/ends as particular co/limits; then we derive a number of results directly from this characterization. The last sections discuss the most interesting examples where co/end calculus serves as a powerful abstract way to do explicit computations in diverse fields like Algebra, Algebraic Topology and Category Theory. The appendices serve to sketch a number of results in theories heavily relying on co/end calculus; the reader who dares to arrive at this point, being completely introduced to the mysteries of co/end fu, can regard basically every statement as a guided exercise. Contents Introduction. 1 1. Dinaturality, extranaturality, co/wedges. 3 2. Yoneda reduction, Kan extensions. 13 3. The nerve and realization paradigm. 16 4. Weighted limits 21 5. Profunctors. 27 6. Operads. 33 Appendix A. Promonoidal categories 39 Appendix B. Fourier transforms via coends. 40 References 41 Introduction. The purpose of this survey is to familiarize the reader with the so-called co/end calculus, gathering a series of examples of its application; the author would like to stress clearly, from the very beginning, that the material presented here makes arXiv:1501.02503v2 [math.CT] 9 Feb 2015 no claim of originality: indeed, we put a special care in acknowledging carefully, where possible, each of the many authors whose work was an indispensable source in compiling this note. -
A Category Theory Primer
A category theory primer Ralf Hinze Computing Laboratory, University of Oxford Wolfson Building, Parks Road, Oxford, OX1 3QD, England [email protected] http://www.comlab.ox.ac.uk/ralf.hinze/ 1 Categories, functors and natural transformations Category theory is a game with objects and arrows between objects. We let C, D etc range over categories. A category is often identified with its class of objects. For instance, we say that Set is the category of sets. In the same spirit, we write A 2 C to express that A is an object of C. We let A, B etc range over objects. However, equally, if not more important are the arrows of a category. So, Set is really the category of sets and total functions. (There is also Rel, the category of sets and relations.) If the objects have additional structure (monoids, groups etc.) then the arrows are typically structure-preserving maps. For every pair of objects A; B 2 C there is a class of arrows from A to B, denoted C(A; B). If C is obvious from the context, we abbreviate f 2 C(A; B) by f : A ! B. We will also loosely speak of A ! B as the type of f . We let f , g etc range over arrows. For every object A 2 C there is an arrow id A 2 C(A; A), called the identity. Two arrows can be composed if their types match: if f 2 C(A; B) and g 2 C(B; C ), then g · f 2 C(A; C ). -
Category Theory Course
Category Theory Course John Baez September 3, 2019 1 Contents 1 Category Theory: 4 1.1 Definition of a Category....................... 5 1.1.1 Categories of mathematical objects............. 5 1.1.2 Categories as mathematical objects............ 6 1.2 Doing Mathematics inside a Category............... 10 1.3 Limits and Colimits.......................... 11 1.3.1 Products............................ 11 1.3.2 Coproducts.......................... 14 1.4 General Limits and Colimits..................... 15 2 Equalizers, Coequalizers, Pullbacks, and Pushouts (Week 3) 16 2.1 Equalizers............................... 16 2.2 Coequalizers.............................. 18 2.3 Pullbacks................................ 19 2.4 Pullbacks and Pushouts....................... 20 2.5 Limits for all finite diagrams.................... 21 3 Week 4 22 3.1 Mathematics Between Categories.................. 22 3.2 Natural Transformations....................... 25 4 Maps Between Categories 28 4.1 Natural Transformations....................... 28 4.1.1 Examples of natural transformations........... 28 4.2 Equivalence of Categories...................... 28 4.3 Adjunctions.............................. 29 4.3.1 What are adjunctions?.................... 29 4.3.2 Examples of Adjunctions.................. 30 4.3.3 Diagonal Functor....................... 31 5 Diagrams in a Category as Functors 33 5.1 Units and Counits of Adjunctions................. 39 6 Cartesian Closed Categories 40 6.1 Evaluation and Coevaluation in Cartesian Closed Categories. 41 6.1.1 Internalizing Composition................. 42 6.2 Elements................................ 43 7 Week 9 43 7.1 Subobjects............................... 46 8 Symmetric Monoidal Categories 50 8.1 Guest lecture by Christina Osborne................ 50 8.1.1 What is a Monoidal Category?............... 50 8.1.2 Going back to the definition of a symmetric monoidal category.............................. 53 2 9 Week 10 54 9.1 The subobject classifier in Graph................. -
WHEN IS ∏ ISOMORPHIC to ⊕ Introduction Let C Be a Category
WHEN IS Q ISOMORPHIC TO L MIODRAG CRISTIAN IOVANOV Abstract. For a category C we investigate the problem of when the coproduct L and the product functor Q from CI to C are isomorphic for a fixed set I, or, equivalently, when the two functors are Frobenius functors. We show that for an Ab category C this happens if and only if the set I is finite (and even in a much general case, if there is a morphism in C that is invertible with respect to addition). However we show that L and Q are always isomorphic on a suitable subcategory of CI which is isomorphic to CI but is not a full subcategory. If C is only a preadditive category then we give an example to see that the two functors can be isomorphic for infinite sets I. For the module category case we provide a different proof to display an interesting connection to the notion of Frobenius corings. Introduction Let C be a category and denote by ∆ the diagonal functor from C to CI taking any object I X to the family (X)i∈I ∈ C . Recall that C is an Ab category if for any two objects X, Y of C the set Hom(X, Y ) is endowed with an abelian group structure that is compatible with the composition. We shall say that a category is an AMon category if the set Hom(X, Y ) is (only) an abelian monoid for every objects X, Y . Following [McL], in an Ab category if the product of any two objects exists then the coproduct of any two objects exists and they are isomorphic.