Browsing 2019 by MFO Scientific Program "OWLF 2019"

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A Cheeger Type Inequality in Finite Cayley Sum Graphs

[OWP-2019-21] Biswas, Arindam; Saha, Jyoti Prakash (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-31) - (5 May - 27 July 2019)

Let $G$ be a finite group and $S$ be a symmetric generating set of $G$ with $|S| = d$ . We show that if the undirected Cayley sum graph $C_{\Sigma}(G,S)$ is an expander graph and is non-bipartite, then the spectrum of its ...
Groups with Spanier-Whitehead Duality

[OWP-2019-23] Nishikawa, Shintaro; Proietti, Valerio (Mathematisches Forschungsinstitut Oberwolfach, 2019-09-17)

We introduce the notion of Spanier-Whitehead $K$ -duality for a discrete group $G$ , defined as duality in the KK-category between two $C*$ -algebras which are naturally attached to the group, namely the reduced group ...
On Co-Minimal Pairs in Abelian Groups

[OWP-2019-19] Biswas, Arindam; Saha, Jyoti Prakash (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-09)

A pair of non-empty subsets $(W,W')$ in an abelian group $G$ is a complement pair if $W+W'=G$ . $W'$ is said to be minimal to $W$ if $W+(W'\setminus \{w'\}) \neq G, \forall \,w'\in W'$ . In general, given an arbitrary subset ...