Moduli and classification of irregular Kaehler manifolds (and algebraic varieties) with Albanese general type fibrations

1991 ◽  
Vol 104 (1) ◽  
pp. 263-289 ◽  
Author(s):  
Fabrizio Catanese
Keyword(s):  
General Type ◽  
Algebraic Varieties ◽  
Kaehler Manifolds

Nets of quadrics and deformations of Σ3〈3〉 singularities

1989 ◽  
Vol 105 (1) ◽  
pp. 109-115
Author(s):  
S. A. Edwards ◽  
C. T. C. Wall
Keyword(s):  
Parameter Space ◽  
General Type ◽  
Single Parameter ◽  
Connected Components ◽  
Quadratic Maps ◽  
Nets Of Quadrics

The 2-jet of a Σ3 map-germ f:(3, 0) → (3, 0) determines a net of quadratic maps from 3 to 3; for nets of general type this jet is sufficient for equivalence. The classification of such nets involves a single parameter c. It is shown in [7], also in [3], that the versai unfolding of f is topologically trivial over the parameter space. However, there are 4 connected components of this space of nets. The main object of this paper is to show that the corresponding unfolded maps are of different topological types.

Some Adjunction-Theoretic Properties of Codimension Two Non-Singular Subvarities of Quadrics

1997 ◽  
Vol 49 (4) ◽  
pp. 675-695
Author(s):  
Mark Andrea A. De Cataldo
Keyword(s):  
General Type ◽  
Codimension Two

AbstractWe make precise the structure of the first two reduction morphisms associated with codimension two non-singular subvarieties of non-singular quadrics Qn, n ≥ 5. We give a coarse classification of the same class of subvarieties when they are assumed not to be of log-general-type.

scholarly journals Algebraic Surfaces of General Type with Small c21 in Positive Characteristic

2008 ◽  
Vol 191 ◽  
pp. 111-134 ◽  
Author(s):  
Christian Liedtke
Keyword(s):  
Characteristic Zero ◽  
General Type ◽  
Positive Characteristic ◽  
Algebraic Surfaces ◽  
Surfaces Of General Type ◽  
Arbitrary Characteristic ◽  
Numerical Invariants ◽  
Characteristic 2

AbstractWe establish Noether’s inequality for surfaces of general type in positive characteristic. Then we extend Enriques’ and Horikawa’s classification of surfaces on the Noether line, the so-called Horikawa surfaces. We construct examples for all possible numerical invariants and in arbitrary characteristic, where we need foliations and deformation techniques to handle characteristic 2. Finally, we show that Horikawa surfaces lift to characteristic zero.

scholarly journals Mixed threefolds isogenous to a product

2019 ◽  
Vol 18 (12) ◽  
pp. 1950239 ◽  
Author(s):  
Christian Gleissner
Keyword(s):  
Finite Group ◽  
Riemann Surfaces ◽  
Mixed Type ◽  
General Type ◽  
Canonical Class ◽  
Trivial Element ◽  
Compact Riemann Surfaces ◽  
A Finite Group ◽  
Full Classification

In this paper, we study threefolds isogenous to a product of mixed type i.e. quotients of a product of three compact Riemann surfaces [Formula: see text] of genus at least two by the action of a finite group [Formula: see text], which is free, but not diagonal. In particular, we are interested in the systematic construction and classification of these varieties. Our main result is the full classification of threefolds isogenous to a product of mixed type with [Formula: see text] in the absolutely faithful case, i.e. any automorphism in [Formula: see text], which restricts to the trivial element in [Formula: see text] for some [Formula: see text], is the identity on the product. Since the holomorphic Euler–Poincaré-characteristic of a smooth threefold of general type with ample canonical class is always negative, these examples lie on the boundary, in the sense of threefold geography. To achieve our result we use techniques from computational group theory. Indeed, we develop a MAGMA algorithm to classify these threefolds for any given value of [Formula: see text] in the absolutely faithful case.

Projective characters and invariants of algebraic varieties

1937 ◽  
Vol 33 (2) ◽  
pp. 188-198
Author(s):  
L. Roth
Keyword(s):  
General Type ◽  
A Priori ◽  
Direct Calculation ◽  
Linear Functions ◽  
Algebraic Varieties ◽  
Arithmetic Genus ◽  
Canonical Systems ◽  
Numerical Invariants ◽  
Simple Notation ◽  
Relative Invariants

It is a familiar fact that the arithmetic genus pa and the arithmetic linear genus ω of a general surface are linear functions of its four projective characters; and we find by direct calculation that a similar property holds for the numerical invariants of a general threefold. The question thus arises, whether this result can be established a priori for any algebraic variety Vk of general type, since in that case we should have a simple means of determining its numerical invariants. It has been shown by Severi that, subject to a certain assumption, the arithmetic genus pk of Vk is a function of its projective characters, while it is known that, for k ≤ 4, pk coincides with the arithmetic genus Pa obtained by the second definition (§ 5). In the present paper we obtain, by using Severi's postulate, expressions for the arithmetic genera of a V3 and a V4 in terms of their projective characters. We obtain also the characters of their virtual canonical systems and hence derive formulae for the relative invariants Ωi. For this purpose we replace certain projective characters of Vk by others which are more easily computed and better adapted to a simple notation.

scholarly journals Non-normal abelian covers

2012 ◽  
Vol 148 (4) ◽  
pp. 1051-1084 ◽  
Author(s):  
Valery Alexeev ◽  
Rita Pardini
Keyword(s):  
Abelian Group ◽  
Moduli Space ◽  
Moduli Spaces ◽  
General Type ◽  
Finite Abelian Group ◽  
Algebraic Varieties ◽  
Surfaces Of General Type ◽  
Normal Case ◽  
Abelian Cover ◽  
Abelian Covers

AbstractAn abelian cover is a finite morphism X→Y of varieties which is the quotient map for a generically faithful action of a finite abelian group G. Abelian covers with Y smooth and X normal were studied in [R. Pardini, Abelian covers of algebraic varieties, J. Reine Angew. Math. 417 (1991), 191–213; MR 1103912(92g:14012)]. Here we study the non-normal case, assuming that X and Y are S2 varieties that have at worst normal crossings outside a subset of codimension greater than or equal to two. Special attention is paid to the case of ℤr2-covers of surfaces, which is used in [V. Alexeev and R. Pardini, Explicit compactifications of moduli spaces of Campedelli and Burniat surfaces, Preprint (2009), math.AG/arXiv:0901.4431] to construct explicitly compactifications of some components of the moduli space of surfaces of general type.

scholarly journals Structure and classification of Hom-associative algebras

2020 ◽  
Vol 24 (1) ◽  
pp. 79-102
Author(s):  
Abdenacer Makhlouf ◽  
Ahmed Zahari
Keyword(s):  
Deformation Theory ◽  
Matrix Algebra ◽  
Algebraic Varieties ◽  
Associative Algebras ◽  
Irreducible Components

The purpose of this paper is to study the structure and the algebraic varieties of Hom-associative algebras. We characterize multiplicative simple Hom-associative algebras and give some examples deforming the 2 × 2-matrix algebra to simple Hom-associative algebras. We provide a classification of n-dimensional Hom-associative algebras for n ≤ 3. Then we study irreducible components using deformation theory.

scholarly journals Classification of algebraic varieties

1977 ◽  
Vol 53 (3) ◽  
pp. 103-105 ◽  
Author(s):  
Shigeru Iitaka
Keyword(s):  
Algebraic Varieties
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