Arc operads and arc algebras.
Augmented Γ-spaces, the stable rank filtration, and a bu analogue of the Whitehead conjecture
We explore connections between our previous paper [J. Reine Angew. Math. 604 (2007)], where we constructed spectra that interpolate between bu and Hℤ, and earlier work of Kuhn and Priddy on the Whitehead conjecture and of Rognes on the stable rank filtration in algebraic K-theory. We construct a "chain complex of spectra" that is a bu analogue of an auxiliary complex used by Kuhn-Priddy; we conjecture that this chain complex is "exact"; and we give some supporting evidence. We tie this to work of...
Bar constructions for topological operads and the Goodwillie derivatives of the identity.
Cochain operations defining Steenrod--products in the bar construction.
Cohomology operations and the Deligne conjecture
The aim of this note, which raises more questions than it answers, is to study natural operations acting on the cohomology of various types of algebras. It contains a lot of very surprising partial results and examples.
Dimension vs. genus: A surface realization of the little k-cubes and an operad
We define a new operad based on surfaces with foliations which contains suboperads. We construct CW models for these operads and provide applications of these models by giving actions on Hochschild complexes (thus making contact with string topology), by giving explicit cell representatives for the Dyer-Lashof-Cohen operations for the 2-cubes and by constructing new Ω spectra. The underlying novel principle is that we can trade genus in the surface representation vs. the dimension k of the little...
Familial 2-functors and parametric right adjoints.
Free -categories.
Generic morphisms, parametric representations and weakly cartesian monads.
Gerbes and homotopy quantum field theories.
Homologie et modèle minimal des algèbres de Gerstenhaber
On étudie ici les notions d’algèbre de Gerstenhaber à homotopie près et d’homologie des algèbres de Gerstenhaber du point de vue de la théorie des opérades. Précisément, on donne une description explicite des -algèbres à homotopie près (c’est-à-dire d’algèbres sur le modèle minimal de l’opérade des algèbres de Gerstenhaber). On décrit également le complexe calculant l’homologie des -algèbres. On donne une suite spectrale qui converge vers cette homologie et quelques exemples de calculs. Enfin...
La renaissance des opérades
On several varieties of cacti and their relations.
On the loop homology of complex projective spaces
In this short note we compute the Chas-Sullivan BV-algebra structure on the singular homology of the free loop space of complex projective spaces. We compare this result with computations in Hochschild cohomology.
Open/Closed string topology and moduli space actions via open/closed Hochschild actions.
Operads for -ary algebras – calculations and conjectures
In [8] we studied Koszulity of a family of operads depending on a natural number and on the degree of the generating operation. While we proved that, for , the operad is Koszul if and only if is even, and while it follows from [4] that is Koszul for even and arbitrary , the (non)Koszulity of for odd and remains an open problem. In this note we describe some related numerical experiments, and formulate a conjecture suggested by the results of these computations.
Operads in iterated monoidal categories.
Operády v současné matematice
Reedy categories which encode the notion of category actions
We study a certain type of action of categories on categories and on operads. Using the structure of the categories Δ and Ω governing category and operad structures, respectively, we define categories which instead encode the structure of a category acting on a category, or a category acting on an operad. We prove that the former has the structure of an elegant Reedy category, whereas the latter has the structure of a generalized Reedy category. In particular, this approach gives a new way to regard...
Simplicial -fold monoidal categories model all loop spaces