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We define a new notion of an algebraic model structure, in which the cofibrations and fibrations are retracts of coalgebras for comonads and algebras for monads, and prove "algebraic" analogs of classical results. Using a modified version…

Category Theory · Mathematics 2011-03-14 Emily Riehl

We define and study the notion of numerical equivalence on algebraic cobordism cycles. We prove that algebraic cobordism modulo numerical equivalence is a finitely generated module over the Lazard ring, and it reproduces the Chow group…

Algebraic Geometry · Mathematics 2015-07-02 Anandam Banerjee , Jinhyun Park

We show how the framework of crossed simplicial groups may be used to provide a classification of topological field theories on open cobordism categories defined by reductions of the structure group to a planar Lie group. Such theories are…

Category Theory · Mathematics 2016-03-09 Walker H. Stern

We show that every affine or projective algebraic variety defined over the field of real or complex numbers is homeomorphic to a variety defined over the field of algebraic numbers. We construct such a homeomorphism by choosing a small…

Algebraic Geometry · Mathematics 2019-12-03 Adam Parusinski , Guillaume Rond

We compute the geometric part of algebraic cobordism over Dedekind domains of mixed characteristic after inverting the positive residue characteristics and prove cases of a Conjecture of Voevodsky relating this geometric part to the Lazard…

Algebraic Topology · Mathematics 2014-04-10 Markus Spitzweck

We present a conjecture in Diophantine geometry concerning the construction of line bundles over smooth projective varieties over $\bar{\mathbb Q}}$. This conjecture, closely related to the Grothendieck Period Conjecture for cycles of…

Algebraic Geometry · Mathematics 2016-02-10 Jean-Benoit Bost

We describe certain almost-simple algebraic supergroups over an algebraically closed field of odd or zero characteristic. In addition to supergroups with simple Lie superalgebras from Kac's theorem, we construct new supergroups whose Lie…

Rings and Algebras · Mathematics 2025-11-21 S. Bouarroudj , A. N. Zubkov

We consider a generalization of the axioms of a TQFT, so called half-projective TQFT's, with an anomaly, $x^{\mu}$, in the composition law. $\mu$ is a coboundary on the cobordism categories with non-negative, integer values. The element $x$…

q-alg · Mathematics 2009-10-30 Thomas Kerler

We construct a theory of motivic cohomology for quasi-compact, quasi-separated schemes of equal characteristic, which is related to non-connective algebraic $K$-theory via an Atiyah--Hirzebruch spectral sequence, and to \'etale cohomology…

K-Theory and Homology · Mathematics 2026-03-30 Elden Elmanto , Matthew Morrow

Some results that are true in classical groups are investigated in generalized groups and are shown to be either generally true in generalized groups or true in some special types of generalized groups. Also, it is shown that a Bol groupoid…

General Mathematics · Mathematics 2010-03-04 J. O. Adeniran , J. T. Akinmoyewa , A. R. T. Solarin , T. G. Jaiyeola

We study PL bordism theories from a quantitative perspective. Such theories include those of PL manifolds, ordinary homology theory, as well as various more exotic theories such as bordism of Witt spaces. In all these cases we show that a…

Geometric Topology · Mathematics 2026-02-25 Fedor Manin , Bena Tshishiku , Shmuel Weinberger

We study equivariant morphisms from zero dimensional schemes to varieties and show that, under suitable assumptions, all such morphisms factor via a canonical one. We relate the above to Algebraic Representations of Ergodic Actions.

Algebraic Geometry · Mathematics 2023-04-05 Avraham Aizenbud , Uri Bader

Let $f : X -> B$ be a projective surjective morphism between quasi-projective varieties. The goal of this paper is the study of the Chow groups of $X$ in terms of the Chow groups of $B$ and of the fibers of $f$. One of the applications…

Algebraic Geometry · Mathematics 2015-04-07 Charles Vial

We introduce a theory of motivic cohomology for quasi-compact quasi-separated schemes, which generalises the construction of Elmanto--Morrow in the case of schemes over a field. Our construction is non-$\mathbb{A}^1$-invariant in general,…

Algebraic Geometry · Mathematics 2025-07-22 Tess Bouis

We prove the exactness of a descent sequence relating the algebraic cobordism groups of a scheme and its envelopes. Analogous sequences for Chow groups and K-theory were previously proved by Gillet.

Algebraic Geometry · Mathematics 2013-01-16 José Luis González , Kalle Karu

We show that for any integer n and any field k of characteristic different from 2 there are at most finitely many isomorphism classes of quadratic morphisms from the projective line over k to itself with a finite postcritical orbit of size…

Algebraic Geometry · Mathematics 2013-08-27 Richard Pink

We discuss properties of complex algebraic orbifold groups, their characteristic varieties, and their abelian covers. In particular, we deal with the question of (quasi)-projectivity of orbifold groups. We also prove a structure theorem for…

Algebraic Geometry · Mathematics 2012-03-09 Enrique Artal Bartolo , Jose Ignacio Cogolludo-Agustin , Daniel Matei

Let $K$ be an algebraically closed field of arbitrary characteristic and let $X$ be an irreducible projective variety over $K$. Let $G\subseteq\text{Bir}(X)$ be a bounded-degree subgroup. We prove that there exists an irreducible projective…

Algebraic Geometry · Mathematics 2024-03-13 She Yang

A semi-projective representation is a homomorphism of a finite group into the group of semi-projective transformations of a finite dimensional vector space over a field. Schur's concept of a representation group for projective…

Group Theory · Mathematics 2023-05-05 Massimiliano Alessandro , Christian Gleissner , Julia Kotonski

We study the general theory of Frobenius algebras with group actions. These structures arise when one is studying the algebraic structures associated to a geometry stemming from a physical theory with a global finite gauge group, i.e.…

Algebraic Geometry · Mathematics 2007-05-23 Ralph M. Kaufmann