P1-0292 — Annual report 2011
1.
Characterizing compact Clifford semigroups that embed into convolution and functor-semigroups

We study algebraic and topological properties of the convolution semigroups of probability measures on a topological groups and show that a compact Clifford topological semigroup ▫$S$▫ embeds into the convolution semigroup ▫$P(G)$▫ over some topological group ▫$G$▫ if and only if ▫$S$▫ embeds into the semigroup ▫$\exp(G)$▫ of compact subsets of ▫$G$▫ if and only if ▫$S$▫ is an inverse semigroup and has zero-dimensional maximal semilattice. We also show that such a Clifford semigroup ▫$S$▫ embeds into the functor-semigroup ▫$F(G)$▫ over a suitable compact topological group ▫$G$▫ for each weakly normal monadic functor ▫$F$▫ in the category of compacta such that ▫$F(G)$▫ contains a ▫$G$▫-invariant element (which is an analogue of the Haar measure on ▫$G$▫).

COBISS.SI-ID: 15950681
2.
Discrete gradient fields on infinite complexes

The aim of this work is to characterize the discrete gradient vector fields on infinite and locally finite simplicial complexes which are induced by a proper discrete Morse function. This characterization is essentially given by the non-existence of closed trajectories and the absence of a certain kind of incidence between monotonous rays in the given field.

COBISS.SI-ID: 15865945
3.
Sublinear Higson corona and Lipschitz extensions

We show that the dimension of the sublinear Higson corona of a metric space ▫$X$▫ is the smallest non-negative integer ▫$m$▫ with the following property: Any norm-preserving asymptotically Lipschitz function from a closed subset ▫$A$▫ of ▫$X$▫ to the Euclidean space of dimension ▫$m+1$▫ extends to a norm-preserving asymptotically Lipschitz function from ▫$X$▫ to the Euclidean space of dimension ▫$m+1$▫. As an application we obtain another proof of the following result of Dranishnikov and Smith: Let ▫$X$▫ be a cocompact proper metric space, which is ▫$M$▫-connected for some $M$, and has the asymptotic Assouad-Nagata dimension finite. Then this dimension equals the dimension of the sublinear Higson corona of ▫$X$▫.

COBISS.SI-ID: 16135001