Coherent prohomotopy theory
(Co)homology of crossed modules with coefficients in a -module.
Colimits for the pro-category of towers of simplicial sets
Combinatorial-geometric aspects of polycategory theory : pasting schemes and higher Bruhat orders (list of results)
Conditions For A Realization Functor To Commute With Finite Products.
Connected sequences of stable derived functors and their applications [Book]
Contractible simplicial objects
We raise the question of when a simplicial object in a catetgory is deemed contractible. The literature offers three definitions. One is the existence of an “extra degeneracy”, indexed by , which does not quite live up to the name. This can be strengthened to a “strong extra degeneracy". Another possibility is that it be homotopic to a constant simplicial object. Despite claims in the literature to the contrary, we show that all three are distinct concepts with strong extra degeneracy implies extra...
Crossed squares and 2-crossed modules of commutative algebras.
Cubical sets and their site.
Cyclic homology, a survey
Decompositions of the category of noncommutative sets and Hochschild and cyclic homology
In this note we show that the main results of the paper [PR] can be obtained as consequences of more general results concerning categories whose morphisms can be uniquely presented as compositions of morphisms of their two subcategories with the same objects. First we will prove these general results and then we will apply it to the case of finite noncommutative sets.
Differential graded Lie algebras controlling infinitesimal deformations of coherent sheaves
Dualization in algebraic K-theory and the invariant e¹ of quadratic forms over schemes
In the classical Witt theory over a field F, the study of quadratic forms begins with two simple invariants: the dimension of a form modulo 2, called the dimension index and denoted e⁰: W(F) → ℤ/2, and the discriminant e¹ with values in k₁(F) = F*/F*², which behaves well on the fundamental ideal I(F)= ker(e⁰). Here a more sophisticated situation is considered, of quadratic forms over a scheme and, more generally, over an exact category with duality. Our purposes are: ...
Finite sets and symmetric simplicial sets.
Formes différentielles et suites spectrales
La théorie de Sullivan de l’homotopie rationnelle introduit l’algèbre des formes différentielles sur un ensemble simplicial. On montre dans cet article qu’en filtrant cette algèbre on peut obtenir une suite spectrale analogue à celle de Serre. On applique ce résultat pour étudier le modèle minimal d’un fibré et pour obtenir une nouvelle démonstration de la suite spectrale d’Eilenberg-Moore.
Freeness conditions for 2-crossed modules and complexes.
Ganea term for CCG-homology of crossed modules.
In [2] an internal homology theory of crossed modules was defined (CCG-homology for short), which is very much related to the homology of the classifying spaces of crossed modules ([5]). The goal of this note is to construct a low-dimensional homology exact sequence corresponding to a central extension of crossed modules, which is quite similar to the one constructed in [3] for group homology.
Generalized homotopy in C-categories.
Graph Cohomology, Colored Posets and Homological Algebra in Functor Categories
The homology theory of colored posets, defined by B. Everitt and P. Turner, is generalized. Two graph categories are defined and Khovanov type graph cohomology are interpreted as Ext* groups in functor categories associated to these categories. The connection, described by J. H. Przytycki, between the Hochschild homology of an algebra and the graph cohomology, defined for the same algebra and a cyclic graph, is explained from the point of view of homological algebra in functor categories.
Higher dimensional Peiffer elements in simplicial commutative algebras.