Expand all Collapse all | Results 26 - 31 of 31 |
26. CJM 1999 (vol 51 pp. 49)
AlgÃ¨bres quasi-commutatives et carrÃ©s de Steenrod Soit $k$ un corps de caract\'eristique $p$ quelconque. Nous
d\'efinissons la cat\'egorie des $k$-alg\`ebres de cocha\^{\i}nes
fortement quasi-commutatives et nous donnons une condition
n\'ecessaire et suffisante pour que l'alg\`ebre de cohomologie \`a
coefficients dans $\mathbb{Z}_2$ d'un objet de cette cat\'egorie soit
un module instable sur l'alg\`ebre de Steenrod \`a coefficients dans
$\mathbb{Z}_2$.
A tout c.w.\ complexe simplement connexe de type fini $X$ on associe une
$k$-alg\`ebre de cocha\^{\i}nes fortement quasi-commutative; la
structure de module sur l'alg\`ebre de Steenrod d\'efinie sur
l'alg\`ebre de cohomologie de celle-ci co\"\i ncide avec celle de
$H^*(X; \mathbb{Z}_2)$.
We define the category of strongly quasi-commutative cochain
$k$-algebras, where $k$ is a field of any characteristic $p$. We give a
necessary and sufficient condition which enables the cohomology algebra
with $\mathbb{Z}_2$-coefficients of an object in this category
to be an unstable module on the $\mathbb{Z}_2$-Steenrod algebra.
To each simply connected c.w.\ complex of finite type $X$ is associated
a strongly quasi-commutative model and the module structure over the
$\mathbb{Z}_2$-Steenrod algebra defined on the cohomology of
this model is the usual structure on $H^*(X; \mathbb{Z}_2)$.
Keywords:algÃ¨bres de cocha\^{\i}nes (fortement) quasi-commutatives, $T (V)$-modÃ¨le, carrÃ©s de Steenrod, quasi-isomorphisme Categories:55P62, 55S05 |
27. CJM 1998 (vol 50 pp. 1048)
Localization theories for simplicial presheaves Most extant localization theories for spaces, spectra and diagrams
of such can be derived from a simple list of axioms which are verified
in broad generality. Several new theories are introduced, including
localizations for simplicial presheaves and presheaves of spectra at
homology theories represented by presheaves of spectra, and a theory
of localization along a geometric topos morphism. The
$f$-localization concept has an analog for simplicial presheaves, and
specializes to the $\hbox{\Bbbvii A}^1$-local theory of
Morel-Voevodsky. This theory answers a question of Soul\'e concerning
integral homology localizations for diagrams of spaces.
Categories:55P60, 19E08, 18F20 |
28. CJM 1998 (vol 50 pp. 845)
Lusternik-Schnirelmann category and algebraic $R$-local homotopy theory In this paper, we define the notion of $R_{\ast}$-$\LS$ category
associated to an increasing system of subrings of $\Q$ and we relate
it to the usual $\LS$-category. We also relate it to the invariant
introduced by F\'elix and Lemaire in tame homotopy theory, in which
case we give a description in terms of Lie algebras and of cocommutative
coalgebras, extending results of Lemaire-Sigrist and F\'elix-Halperin.
Categories:55P50, 55P62 |
29. CJM 1998 (vol 50 pp. 342)
Shape fibrations, multivalued maps and shape groups The notion of shape fibration with the near lifting of near
multivalued paths property is studied. The relation of these
maps---which agree with shape fibrations having totally disconnected
fibers---with Hurewicz fibrations with the unique path lifting
property is completely settled. Some results concerning homotopy and
shape groups are presented for shape fibrations with the near lifting
of near multivalued paths property. It is shown that for this class of
shape fibrations the existence of liftings of a fine multivalued map,
is equivalent to an algebraic problem relative to the homotopy, shape
or strong shape groups associated.
Keywords:Shape fibration, multivalued map, homotopy groups, shape, groups, strong shape groups Categories:54C56, 55P55, 55Q05, 55Q07, 55R05 |
30. CJM 1997 (vol 49 pp. 1323)
Stable parallelizability of partially oriented flag manifolds II In the first paper with the same title the authors
were able to determine all partially oriented flag
manifolds that are stably parallelizable or
parallelizable, apart from four infinite families
that were undecided. Here, using more delicate
techniques (mainly K-theory), we settle these
previously undecided families and show that none of
the manifolds in them is stably parallelizable,
apart from one 30-dimensional manifold which still
remains undecided.
Categories:57R25, 55N15, 53C30 |
31. CJM 1997 (vol 49 pp. 855)
Rational Classification of simple function space components for flag manifolds. Let $M(X,Y)$ denote the space of all continous functions
between $X$ and $Y$ and $M_f(X,Y)$ the path component
corresponding to a given map $f: X\rightarrow Y.$ When $X$ and
$Y$ are classical flag manifolds, we prove the components of
$M(X,Y)$ corresponding to ``simple'' maps $f$ are classified
up to rational homotopy type by the dimension of the kernel of
$f$ in degree two
cohomology. In fact, these components are themselves all products
of flag manifolds and odd spheres.
Keywords:Rational homotopy theory, Sullivan-Haefliger model. Categories:55P62, 55P15, 58D99. |