To see the other types of publications on this topic, follow the link: Symmetric varieties.
Dissertations / Theses on the topic 'Symmetric varieties'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 26 dissertations / theses for your research on the topic 'Symmetric varieties.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Esposito, Francesco. "Orbits in symmetric varieties." Doctoral thesis, La Sapienza, 2005. http://hdl.handle.net/11573/917110.
Full text
2
Young, Ian David. "Symmetric squares of modular Abelian varieties." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500087.
Full text
3
mazzon, andrea. "Hilbert functions and symmetric tensors identifiability." Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1133145.
Full textAbstract:
We study the Waring decompositions of a given symmetric tensor using tools of algebraic geometry for the study of finite sets of points. In particular we use the properties of the Hilbert functions and the Cayley-Bacharach property to study the uniqueness of a given decomposition (the identifiability problem), and its minimality, and show how, in some cases, one can effectively determine the uniqueness even in some range in which the Kruskal's criterion does not apply. We give also a more efficient algorithm that, under some hypothesis, certify the identifiability of a given symmetric tensor.
4
Mbirika, Abukuse III. "Analysis of symmetric function ideals: towards a combinatorial description of the cohomology ring of Hessenberg varieties." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/708.
Full textAbstract:
Symmetric functions arise in many areas of mathematics including combinatorics, topology and algebraic geometry. Using ideals of symmetric functions, we tie these three branches together. This thesis generalizes work of Garsia and Procesi in 1992 that gave a quotient ring presentation for the cohomology ring of Springer varieties.
Let R be the polynomial ring Ζ[x1,…,xn]. We present two different ideals in R. Both are parametrized by a Hessenberg function h, namely a nondecreasing function that satisfies h(i) ≥ i for all i. The first ideal, which we call Ih, is generated by modified elementary symmetric functions. The ideal I_h generalizes the work of Tanisaki who gave a combinatorial description of the ideal used in Garsia and Procesi's quotient ring. Like the Tanisaki ideal, the generating set for Ih is redundant. We give a minimal generating set for this ideal. The second ideal, which we call Jh, is generated by modified complete symmetric functions. The generators of this ideal form a Gröbner basis, which is a useful property. Using the Gröbner basis for Jh, we identify a basis for the quotient R/Jh.
We introduce a partial ordering on the Hessenberg functions, and in turn we discover nice nesting properties in both families of ideals. When h>h', we have Ih ⊂ Ih' and Jh ⊂ Jh'. We prove that Ih equals Jh when h is maximal. Since Ih is the ideal generated by the elementary symmetric functions when h is maximal, the generating set for Jh forms a Gröbner basis for the elementary symmetric functions. Moreover, the quotient R/Jh gives another description of the cohomology ring of the full flag variety.
The generators of the ring R/Jh are in bijective correspondence with the Betti numbers of certain Hessenberg varieties. These varieties are a two-parameter generalization of Springer varieties, parametrized by a nilpotent operator X and a Hessenberg function h. These varieties were introduced in 1992 by De Mari, Procesi and Shayman. We provide evidence that as h varies, the quotient R/Jh may be a presentation for the cohomology ring of a subclass of Hessenberg varieties called regular nilpotent varieties.
5
Shu, Cheng. "E-Polynomial of GLn⋊<σ>-character varieties." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7038.
Full textAbstract:
Soit σ l'automorphisme par transpose-inverse de GLn, qui définit un produit semi-direct GLn⋊<σ>. Soit Y→X un revê-tement double de surfaces de Riemann, qui est exactement la partie non ramifiée d'un revêtement ramifié de surfaces de Riemann compactes. L'élément non trivial de Gal(Y/X) sera noté τ. A chaque point ramifié enlevé, on associe une GLn(C)-classe de conjugaison contenue dans la composante connexe GLn(C).σ, et on exige que la famille C des classes de conjugaison soient générique. La variété de GLn(C)⋊<σ>-caractère que l'on a étudié est l'espace de module des pairs (L,Φ) formés d'un système local L sur Y et d'un isomorphisme Φ:L → τ*L*, dont les monodromies autour des points ramifiés sont déterminées par C. On calcule le E-polynôme de cette variété de caractère. A ce fin, on utilise un théorème de Katz, ce qui nous ramème au comptage des points sur corps finis. La formule de comptage fait intervenir les caractères irréductibles de GL_n(q)⋊<σ>, et donc la table des l-adic caractères de ce groupe est déterminée au fur et à mesure. Le polynôme qui en résulte s'exprime comme un produit scalaire de certaines fonctions symétriques associées au produit de couronne (Z/2Z)^N⋊(S_N), avec N=[n/2]Let σ be the transpose-inverse automorphism of GLn so that we have a semi-direct product GLn⋊<σ>. Let Y→X be a double covering of Riemann surfaces, which is exactly the unramified part of a ramified covering of compact Riemann surfaces. The non trivial covering transformation is denoted by τ. To each puncture (removed ramification point), we prescribe a GLn(C)-conjugacy class contained in the connected component GLn(C).σ . And we require the collection C of these conjugacy classes to be generic. Our GLn(C)⋊<σ>-character variety is the moduli of the pairs (L,Φ), where L is a local system on Y and Φ:L → τ*L* is an isomorphism, whose monodromy at the punctures are determined by C. We compute the E-polynomial of this character variety. To this end, we use a theorem of Katz and translate the problem to point-counting over finite fields. The counting formula involves the irreducible characters of GL_n(q)⋊<σ>, and so the l-adic character table of GL_n(q)⋊<σ> is determined along the way. The resulting polynomial is expressed as the in-ner product of certain symmetric functions associated to the wreath product (Z/2Z)^N⋊(S_N), with N=[n/2]
6
Chen, Jiaming. "Topology at infinity and atypical intersections for variations of Hodge structures." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7049.
Full textAbstract:
Cette thèse étudie les aspects topologiques et géométriques de certains espaces intéressants issus de la théorie de Hodge, tels que les variétés localement symétriques, et leur généralisation, les variétés de Hodge ; ainsi que les applications de périodes qui y prennent valeur.Au chapitre 1 (travail commun avec Looijenga), nous étudions la compactification de Baily-Borel des variétés localement symétriques et ses variantes toroïdales, ainsi que la compactification de Deligne-Mumford de l’espace de module des courbes d’un point de vue topologique. Nous définissons un "type d’homotopie champêtre" pour ces espaces comme le type d’homotopie d’une petite catégorie. Nous généralisons ainsi un ancien résultat de Charney-Lee sur la compactification de Baily-Borel de Ag et récupérons (et reformulons) un résultat plus récent d’Ebert-Giansiracusa sur les compactifications de Deligne-Mumford. Nous décrivons également en ces termes une extension de l’application de périodes pour les surfaces de Riemann. Dans le chapitre 2 (travail commun avec Looijenga), nous donnons une preuve algébro-géométrique relativement simple d’un autre résultat de Charney et Lee sur la cohomologie stable de la compactification de Satake-Baily-Borel de Ag et montrons que cette cohomologie stable est munie d’une structure de Hodge mixte dont nous déterminons les nombres de Hodge.Dans le chapitre 3 (chapitre principal de cette thèse), nous étudions un problème d’intersections atypiques pour une variation de structures de Hodge V sur une variété quasi-projective complexe irréductible lisse S. Nous montrons que l’union des sousvariétés spéciales non-facteur pour (S,V), qui sont de type Shimura avec des applications de périodes dominantes, est une union finie de sous-variétés spéciale des S. Ceci démontre une conjecture de KlinglerThis thesis studies topological and geometrical aspects of some interesting spaces springing from Hodge theory, such as locally symmetric varieties, and their generalization, Hodge varieties; and the period maps which take value in them.In Chapter 1 (joint work with Looijenga) we study the Baily-Borel compactifications of locally symmetric varieties and its toroidal variants, as well as the Deligne-Mumford compactification of the moduli of curves from a topological viewpoint. We define a "stacky homotopy type" for these spaces as the homotopy type of a small category and thus generalize an old result of Charney-Lee on the Baily-Borel compactificationof Ag and recover (and rephrase) a more recent one of Ebert-Giansiracusa on the Deligne-Mumford compactification. We also describe an extension of the period map for Riemann surfaces in these terms.In Chapter 2 (joint work with Looijenga) we give a relatively simple algebrogeometric proof of another result of Charney and Lee on the stable cohomology of the Satake-Baily-Borel compactification of Ag and show that this stable cohomology comes with a mixed Hodge structure of which we determine the Hodge numbers.In Chapter 3 (themain chapter of this thesis) we study an atypical intersection problem for an integral polarized variation of Hodge structure V on a smooth irreducible complex quasi-projective variety S. We show that the union of the non-factor special subvarieties for (S,V), which are of Shimura type with dominant period maps, is a finite union of special subvarieties of S. This proves a conjecture of Klingler
7
Menes, Thibaut. "Grandes valeurs des formes de Maass sur des quotients compacts de grassmanniennes hyperboliques dans l’aspect volume." Electronic Thesis or Diss., Paris 13, 2024. http://www.theses.fr/2024PA131059.
Full textAbstract:
Soient n > m = 1 des entiers tels que n + m >= 4 soit pair. On prouve l’existence, dans l’aspect volume, de formes de Maass exceptionnelles sur des quotients compacts de la grassmanienne hyperbolique de signature (n,m). La méthode repose sur le travail de Rudnick et Sarnak, étendu par Donnelly puis généralisé par Brumley et Marshall en rang supérieur. Celle-ci combine un argument de comptage et une relation de périodes permettant de montrer qu’une certaine période distingue les relèvements thêta depuis un groupe auxiliaire. La structure de niveau est définie relativement à cette période et le groupe auxiliaire qui intervient est U(m,m) ou Sp_2m(R), de sorte que (U(n,m),U(m,m)) ou (O(n,m),Sp_2m(R)) soit une paire duale réductive de type 1. La borne inférieure s’exprime naturellement, à un facteur logarithmique près, comme le quotient des volumes avec la structure de congruence principale sur le groupe auxiliaireLet n > m = 1 be integers such that n + m >= 4 is even. We prove the existence, in the volume aspect, of exceptional Maass forms on compact quotients of the hyperbolic Grassmannian of signature (n,m). The method builds upon the work of Rudnick and Sarnak, extended by Donnelly and then generalized by Brumley and Marshall to higher rank. It combines a counting argument with a period relation, showingthat a certain period distinguishes theta lifts from an auxiliary group. The congruence structure is defined with respect to this period and the auxiliary group is either U(m,m) or Sp_2m(R), making (U(n,m),U(m,m)) or (O(n,m),Sp_2m(R)) a type 1 dual reductive pair. The lower bound is naturally expressed, up to a logarithmic factor, as the ratio of the volumes, with the principal congruence structure on the auxiliary group
8
Petracci, Andrea. "On Mirror Symmetry for Fano varieties and for singularities." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/55877.
Full textAbstract:
In this thesis we discuss some aspects of Mirror Symmetry for Fano varieties and toric singularities. We formulate a conjecture that relates the quantum cohomology of orbifold del Pezzo surfaces to a power series that comes from Fano polygons. We verify this conjecture in some cases, in joint work with A. Oneto. We generalise the Altmann–Mavlyutov construction of deformations of toric singularities: from Minkowski sums of polyhedra we construct deformations of affine toric pairs. Moreover, we propose an approach to the study of deformations of Gorenstein toric singularities of dimension 3 in the context of the Gross–Siebert program. We construct deformations of polarised projective toric varieties by deforming their affine cones. This method is explicit in terms of Cox coordinates and it allows us to give explicit equations for a construction, due to Ilten, which produces a deformation between two toric Fano varieties when their corresponding polytopes are mutation equivalent. We also provide examples of Gorenstein toric Fano 3-folds which are locally smoothable, but not globally smoothable.
9
Prince, Thomas. "Applications of mirror symmetry to the classification of Fano varieties." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43374.
Full textAbstract:
In this dissertation we discuss two new constructions of Fano varieties, each directly inspired by ideas in Mirror Symmetry. The first recasts the Fanosearch program (Coates--Corti--Kasprzyk et al.) for surfaces in terms of a construction related to the SYZ conjecture. In particular we construct Q-Gorenstein smoothings of toric varieties via an application of the Gross-Siebert algorithm to certain affine manifolds. We recover the theory of combinatorial mutation, which plays a central role in the Fanosearch program, from these affine manifolds. Combining this construction and the work of Gross--Hacking--Keel on log Calabi--Yau surfaces we produce a cluster structure on the mirror to a log del Pezzo surface proposed by Coates--Corti--et al. We exploit the cluster structure, and the connection to toric degenerations, to prove two classification results for Fano polygons. This cluster variety is equipped with a superpotential defined on each chart by a so-called maximally mutable Laurent polynomial. We study an enumerative interpretation of this superpotential in terms of tropical disc counting in the example of the projective plane (with a general choice of boundary divisor). In the second part we develop a new construction of Fano toric complete intersections in higher dimensions. We first consider the problem of finding torus charts on the Hori--Vafa/Givental model, adapting the approach taken by Przyjalkowski. We exploit this to identify 527 new families of four-dimensional Fano manifolds. We then develop an inverse algorithm, Laurent Inversion, which decorates a Fano polytope P with additional information used to construct a candidate ambient space for a complete intersection model of the toric variety defined by P. Moving in the linear system defining this complete intersection allows us to construct new models of known Fano manifolds, and also to construct new examples of Fano manifolds from conjectured mirror Laurent polynomials. We use this algorithm to produce families simultaneously realising certain collections of 'commuting' mutations, extending the connection between polytope mutation and deformations of toric varieties.
10
Li, Binru [Verfasser], and Fabrizio [Akademischer Betreuer] Catanese. "Moduli spaces of varieties with symmetries / Binru Li. Betreuer: Fabrizio Catanese." Bayreuth : Universität Bayreuth, 2016. http://d-nb.info/1113107324/34.
Full text
11
Perevalov, Eugene V. "Type II/heterotic duality and mirror symmetry /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Full text
12
Beckwith, Olivia D. "On Toric Symmetry of P1 x P2." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/hmc_theses/46.
Full textAbstract:
Toric varieties are a class of geometric objects with a combinatorial structure encoded in polytopes. P1 x P2 is a well known variety and its polytope is the triangular prism. Studying the symmetries of the triangular prism and its truncations can lead to symmetries of the variety. Many of these symmetries permute the elements of the cohomology ring nontrivially and induce nontrivial relations. We discuss some toric symmetries of P1 x P2, and describe the geometry of the polytope of the corresponding blowups, and analyze the induced action on the cohomology ring. We exhaustively compute the toric symmetries of P1 x P2.
13
TAMBORINI, CAROLINA. "On totally geodesic subvarieties in the Torelli locus and their uniformizing symmetric spaces." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/371476.
Full textAbstract:
Oggetto di questa tesi sono le sottovarietà totalmente geodetiche dello spazio dei moduli A_g di varietà abeliane principalmente polarizzate e la loro relazione con il luogo di Torelli. Questo è definito come la chiusura in A_g dell'immagine dello spazio dei moduli M_g di curve algebriche complesse lisce di genere g tramite la mappa di Torelli j: M_g-->A_g. Lo spazio dei moduli A_g è un quoziente dello spazio di Siegel, che è uno spazio simmetrico. Una sottovarietà algebrica di A_g è totalmente geodetica se è l'immagine, tramite la naturale mappa di proiezione, di una qualche sottovarietà totalmente geodetica dello spazio di Siegel. Ci si aspetta che j(M_g) contenga poche sottovarietà totalmente geodetiche di A_g. Questo è anche in accordo con la congettura di Coleman-Oort. La geometria differenziale degli spazi simmetrici si può descrivere attraverso la teoria di gruppi e algebre di Lie. In particolare, le sottovarietà totalmente geodetiche di spazi simmetrici possono essere caratterizzate in termini di algebre di Lie. Queste considerazioni sono alla base della trattazione svolta in questa tesi, in cui utilizziamo alcuni strumenti della teoria di Lie per indagare alcuni aspetti geometrici dell'inclusione di j(M_g) in A_g. I principali risultati presentati sono i seguenti. Nel Capitolo 2, consideriamo il pull-back dell'operazione di Lie-bracket sullo spazio tangente ad A_g tramite la mappa di Torelli e lo caratterizziamo in termini della geometria della curva. Per farlo usiamo il nucleo di Bergman associato alla curva. Inoltre, colleghiamo il nucleo di Bergman alla seconda forma fondamentale della mappa Torelli. Nel Capitolo 3, determiniamo quale spazio simmetrico uniforma ciascuno dei controesempi noti alla congettura di Coleman-Oort attraverso il calcolo della decomposizione dell'algebra di Lie associata. Questi esempi noti erano stati ottenuti studiando famiglie di rivestimenti di Galois. Nel capitolo 4 ci concentriamo sullo studio di queste famiglie e descriviamo una nuova costruzione topologica di famiglie di G-rivestimenti di P^1.This thesis deals with totally geodesic subvarieties of the moduli space A_g of principally polarized abelian varieties and their relation with the Torelli locus. This is the closure in A_g of the image of the moduli space M_g of smooth, complex algebraic curves of genus g via the Torelli map j: M_g-->A_g. The moduli space A_g is a quotient of the Siegel space, which is a Riemannian symmetric space. An algebraic subvariety of A_g is totally geodesic if it is the image, under the natural projection map, of some totally geodesic submanifold of the Siegel space. Geometric considerations lead to the expectation that j(M_g) should contain very few totally geodesic subvarieties of A_g. This expectation also agrees with the Coleman-Oort conjecture. The differential geometry of symmetric spaces is described through Lie theory. In particular, totally geodesic submanifolds can be characterized via Lie algebras. This motivates the discussion carried out in this thesis, in which we use some Lie-theoretic tools to investigate geometric aspects of the inclusion of j(M_g) in A_g. The main results presented are the following. In Chapter 2, we consider the pull-back of the Lie bracket operation on the tangent space of A_g via the Torelli map, and we characterize it in terms of the geometry of the curve. We use the Bergman kernel form associated with the curve. Also, we link the Bergman kernel form to the second fundamental form of the Torelli map. In Chapter 3, we determine which symmetric space uniformizes each of the known counterexamples to the Coleman-Oort conjecture via the computation of the associated Lie algebra decomposition. These known examples were obtained studying families of Galois coverings of curves. Chapter 4 focuses on these families for their own sake, and we describe a new topological construction of families of G-coverings of the line.
14
Liu, Jie. "Géométrie des variétés de Fano : sous-faisceaux du fibré tangent et diviseur fondamental." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4038/document.
Full textAbstract:
Cette thèse est consacrée à l'étude de la géométrie des variétés de Fano complexes en utilisant les propriétés des sous-faisceaux du fibré tangent et la géométrie du diviseur fondamental. Les résultats principaux compris dans ce texte sont : (i) Une généralisation de la conjecture de Hartshorne: une variété lisse projective est isomorphe à un espace projectif si et seulement si son fibré tangent contient un sous-faisceau ample.(ii) Stabilité du fibré tangent des variétés de Fano lisses de nombre de Picard un : à l'aide de théorèmes d'annulation sur les espaces hermitiens symétriques irréductibles de type compact M, nous montrons que pour presque toute intersection complète générale dans M, le fibré tangent est stable. La même méthode nous permet de donner une réponse sur la stabilité de la restriction du fibré tangent de l'intersection complète à une hypersurface générale.(iii) Non-annulation effective pour des variétés de Fano et ses applications : nous étudions la positivité de la seconde classe de Chern des variétés de Fano lisses de nombre de Picard un. Ceci nous permet de montrer un théorème de non-annulation pour les variétés de Fano lisses de dimension n et d'indice n-3. Comme application, nous étudions la géométrie anticanonique des variétés de Fano et nous calculons les constantes de Seshadri des diviseurs anticanoniques des variétés de Fano d'indice grand.(iv) Diviseurs fondamentaux des variétés de Moishezon lisses de dimension trois et de nombre de Picard un : nous montrons l'existence d'un diviseur lisse dans le système fondamental dans certain cas particulierThis thesis is devoted to the study of complex Fano varieties via the properties of subsheaves of the tangent bundle and the geometry of the fundamental divisor. The main results contained in this text are:(i) A generalization of Hartshorne's conjecture: a projective manifold is isomorphic to a projective space if and only if its tangent bundle contains an ample subsheaf.(ii) Stability of tangent bundles of Fano manifolds with Picard number one: by proving vanishing theorems on the irreducible Hermitian symmetric spaces of compact type M, we establish that the tangent bundles of almost all general complete intersections in M are stable. Moreover, the same method also gives an answer to the problem of stability of the restriction of the tangent bundle of a complete intersection on a general hypersurface.(iii) Effective non-vanishing for Fano varieties and its applications: we study the positivity of the second Chern class of Fano manifolds with Picard number one, this permits us to prove a non-vanishing result for n-dimensional Fano manifolds with index n-3. As an application, we study the anticanonical geometry of Fano varieties and calculate the Seshadri constants of anticanonical divisors of Fano manifolds with large index.(iv) Fundamental divisors of smooth Moishezon threefolds with Picard number one: we prove the existence of a smooth divisor in the fundamental linear system in some special cases
15
Wasserman, Benjamin. "Variétés magnifiques de rang deux." Grenoble 1, 1997. http://www.theses.fr/1997GRE10037.
Full textAbstract:
Soit g un groupe reductif complexe (connexe). Les g-varietes magnifiques les plus connues sont celles de rang zero, a savoir les varietes de drapeaux generalisees g/p, celles de rang un, classifiees par akhiezer, et certaines varietes symetriques completes decrites par de concini et procesi comme par exemple le celebre espace des coniques completes. Il y a recemment un interet renouvele pour les varietes magnifiques de rang deux car des travaux de luna, brion, pauer et knop montrent que celles-ci jouent un role clef dans la theorie des varietes spheriques. L'objectif de ce travail est la classification des varietes magnifiques de rang deux. Ces dernieres peuvent se caracteriser de la maniere suivante. Ce sont des g-varietes lisses completes contenant quatre orbites, a savoir une orbite dense et deux orbites de codimension un dont les adherences d#1 et d#2 se coupent transversalement en la quatrieme orbite qui est de codimension deux. Nous avons recueilli nos resultats dans des tables, contenant groupes d'isotropie et donnees combinatoires en rapport avec la theorie des varietes spheriques.
16
Verovic, Patrick. "Entropies et métriques de Finsler." Grenoble 1, 1996. http://www.theses.fr/1996GRE10138.
Full textAbstract:
Pose au debut des annees 80 par a. Katok et m. Gromov, le probleme riemannien de l'entropie minimale a recu une reponse positive en 1994 grace aux resultats de g. Besson, g. Courtois et s. Gallot. Comme un prolongement de ce travail, l'objet de cette these est l'etude du minimum des entropies volumique et topologique pour les metriques de finsler qui constituent la plus petite extension de la geometrie de riemann. Les trois premiers chapitres conduisent a la construction explicite d'un contre-exemple general a la conjecture finslerienne de l'entropie volumique minimale sur les espaces riemanniens compacts, localement symetriques, de type non-compact et de rang au moins egal a deux. De plus, ce contre-exemple est l'unique minimum de l'entropie volumique parmi les metriques de finsler g-invariantes normalisees par le volume finslerien de la variete. Dans une deuxieme partie, relative au cas du rang un et regroupant les chapitres iv et v, on prouve, avec la meme normalisation que precedemment, le caractere critique des metriques riemanniennes hyperboliques pour l'entropie topologique sur l'ensemble de toutes les metriques de finsler d'une variete compacte de dimension quelconque. Par ailleurs, nous obtenons un resultat identique pour les surfaces compactes en normalisant par le volume de liouville des fibres spheriques, et ce, apres avoir montre que les deux manieres de normaliser ne sont pas equivalentes dans le cadre de la geometrie finslerienne
17
Ruzzi, Alessandro. "Projectively normal complete symmetric varieties and Fano complete symmetric varieties." Phd thesis, 2006. http://tel.archives-ouvertes.fr/tel-00575974.
Full textAbstract:
Cette thèse est subdivisée en deux parties. Dans la premier, je étudie la normalité projective de variétés symétriques, tandis que dans la deuxième je prouve des résultats partiels sur la classification de variétés symétriques de Fano (i.e. avec fibré anti-canonique ample). Dans [R. Chirivì, A. Maffei, Projective normality of complete symmetric varieties, Duke Math. J. 122 (1) (2004) 93-123], les authors ont prouvé la surjectivité du produit de sections de deux fibrés en droites globalement engendrés sur le plongement magnifique d'un espace symétrique (adjoint). Donné deux fibrés en droites amples sur une variété symétrique toroïdale compacte et lisse, je prouve deux critères pour la surjectivité du produit de sections. Grace à tels critères on se peut réduire à étudier le même problème sur la variété torique compacte (respectivement ouverte) associé. De plus, j'ai trouvé des familles de variétés symétriques toroïdales complètes, en particulier lesquelles avec rang 2, telles que le produit de sections de n'import quel fibré en droites ample est surjectif. Dans la deuxième part de ma thèse, j'ai d'abord classifié les variétés symétriques de Fano avec rang arbitraire et que l'on peut obtenir à partir du plongement magnifique par une succession des éclatements le long d'orbites fermées. Quand le rang est au plus trois, j'ai obtenu des résultats plus précis. Les variétés symétriques projectives avec rang un sont tous lisse et magnifique par un résultat classique dû à Akhiezer. J'ai classifié les variétés symétriques toroïdales projectives lisses de rang 2 dont le fibré anti-canonique est ample, respectivement globalement engendré. De plus, j'ai classifié les variétés symétriques de Fano avec rang 3 que l'on peut obtenir à partir du plongement magnifique par une succession des éclatements des sous-variétés G-stables. On peut observer que n'import quelle variété symétrique complete est dominé par une variété que l'on peut obtenir à partir du plongement magnifique par une succession des éclatements des sous-variétés G-stables de codimension 2.
18
"Counting Borel Orbits in Classical Symmetric Varieties." Tulane University, 2018.
Find full textAbstract:
acase@tulane.eduLet G be a reductive group, B be a Borel subgroup, and let K be a symmetric subgroup of G. The study of B orbits in a symmetric variety G/K or, equivalently, the study of K orbits in a flag variety G/B has importance in the study of Harish-Chandra modules; it comes with many interesting Schubert calculus problems. Although this subject is very well studied, it still has many open problems from combinatorial point of view. The most basic question that we want to be able to answer is that how many B orbits there are in G/K. In this thesis, we study the enumeration problem of Borel orbits in the case of classical symmetric varieties. We give explicit formulas for the numbers of Borel orbits on symmetric varieties for each case and determine the generating functions of these numbers. We also explore relations to lattice path enumeration for some cases. In type A, we realize that Borel orbits are parameterized by the lattice paths in a pxq grid moving by only horizontal, vertical and diagonal steps weighted by an appropriate statistic. We provide extended results for type C as well. We also present various t-analogues of the rank generating function for the inclusion poset of Borel orbit closures in type A.
1
Ozlem Ugurlu
19
Oeding, Luke. "G-Varieties and the Principal Minors of Symmetric Matrices." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-526.
Full textAbstract:
The variety of principal minors of nxn symmetric matrices, denoted Zn, can be
described naturally as a projection from the Lagrangian Grassmannian. Moreover, Zn
is invariant under the action of a group G C GL(2n) isomorphic to (SL(2)xn) x Sn.
One may use this symmetry to study the defining ideal of Zn as a G-module via a
coupling of classical representation theory and geometry. The need for the equations
in the defining ideal comes from applications in matrix theory, probability theory,
spectral graph theory and statistical physics.
I describe an irreducible G-module of degree 4 polynomials called the hyperdeterminantal
module (which is constructed as the span of the G-orbit of Cayley's
hyperdeterminant of format 2 x 2 x 2) and show that it that cuts out Zn set theoretically.
This result solves the set-theoretic version of a conjecture of Holtz and
Sturmfels and gives a collection of necessary and sufficient conditions for when it is
possible for a given vector of length 2n to be the principal minors of a symmetric
n x n matrix.
In addition to solving the Holtz and Sturmfels conjecture, I study Zn as a prototypical
G-variety. As a result, I exhibit the use of and further develop techniques
from classical representation theory and geometry for studying G-varieties.
20
Ryan, Philip D. "Some examples in the Bruhat order on symmetric varieties." Master's thesis, 1991. http://hdl.handle.net/1885/139515.
Full text
21
Buch, Anders Skovsted. "Combinatorics of degeneracy loci /." 1999. http://wwwlib.umi.com/dissertations/fullcit/9943050.
Full text
22
Karnataki, Aditya Chandrashekhar. "Two theorems on Galois representations and Shimura varieties." Thesis, 2016. https://hdl.handle.net/2144/17738.
Full textAbstract:
One of the central themes of modern Number Theory is to study properties of Galois and automorphic representations and connections between them. In our dissertation, we describe two different projects that study properties of these objects. In our first project, which is analytic in nature, we consider Artin representations of Q of dimension 3 that are self-dual. We show that these occur with density 0 when counted using the conductor. This provides evidence that self-dual representations should be rare in all dimensions. Our second project, which is more algebraic in nature, is related to automorphic representations. We show the existence of canonical models for certain unitary Shimura varieties. This should help us in computing certain cohomology groups of these varieties, in which regular algebraic automorphic representations having useful properties should be found.
23
Wang, Qiang. "Classification of K-F-orbits of unipotent elements in symmetric F-varieties of SL(n, F)." 2010. http://www.lib.ncsu.edu/theses/available/etd-03312010-232853/unrestricted/etd.pdf.
Full text
24
Beun, Stacy L. "On the classification of orbits of minimal parabolic k-subgroups acting on symmetric k-varieties of SL(n,k)." 2008. http://www.lib.ncsu.edu/theses/available/etd-03172008-184841/unrestricted/etd.pdf.
Full text
25
Yao, Yuan active 2013. "A criterion for toric varieties." 2013. http://hdl.handle.net/2152/21178.
Full textAbstract:
We consider the pair of a smooth complex projective variety together with an anti-canonical simple normal crossing divisor (we call it "log Calabi- Yau"). Standard examples are toric varieties together with their toric boundaries (we call them "toric pairs"). We provide a numerical criterion for a general log Calabi-Yau to be toric by an inequality between its dimension, Picard number and the number of boundary components. The problem originates in birational geometry and our proof is constructive, motivated by mirror symmetry.text
26
Chen, Meng [Verfasser]. "Complex multiplication, rationality and mirror symmetry for abelian varieties and K3 surfaces / vorgelegt von Meng Chen." 2007. http://d-nb.info/984310568/34.
Full text