Univerza na Primorskem Fakulteta za matematiko, naravoslovje in informacijske tehnologije

Raziskovalni matematični seminar - Arhiv

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Datum in ura / Date and time: 27.10.14
Predavalnica / Location: FAMNIT-SEMIN
Predavatelj / Lecturer: Istvan Kovacs (UP FAMNIT)
Naslov / Title: Finite CI-groups and Schur rings
Vsebina / Abstract:

A Cayley graph Cay(G,S) is called a CI-graph if for every subset T
of G, if Cay(G,T) and Cay(G,S) are isomorphic, then T=f(S) for some automorphism f of G. The group G is called a DCI-group if every Cayley graph of G is a CI-graph, and it is called a CI-group if every undirected Cayley graph of G is a CI-graph. Although there is a restrictive list of potentional CI-groups (Li-Lu-Pálfy, 2007), only a few classes of groups have been proved to be indeed CI; in several cases the proof was obtained by studying the Schur rings over the given group.  In my talk I will review the Schur ring method.

Datum in ura / Date and time: 20.10.14
Predavalnica / Location: FAMNIT-SEMIN
Predavatelj / Lecturer: Ademir Hujdurović
Naslov / Title: Generalized Cayley graphs
Vsebina / Abstract:

Generalized Cayley graphs were defined by D.Marušič, R. Scapellato and N. Zagaglia Salvi in 1992. They studied properties of such graphs, mostly related to double coverings of graph. They also posed a question whether there exists a generalized Cayley graph which is vertex-transitive but not Cayley graph.

In this talk, as an affirmative answer to this question, I will present two infinite families of such graphs. Further, some interesting properties of generalized Cayley graph will be given, as well as the proof that every generalized Cayley graph admits a semiregular automorphism. 
This is a joint work with Klavdija Kutnar and Dragan Marušič.

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Datum in ura / Date and time: 13.10.14
Predavalnica / Location: FAMNIT-SEMIN
Predavatelj / Lecturer: György Pál Gehér (University of Szeged and University of Debrecen, Hungary)
Naslov / Title: A two dimensional matrix problem of Molnar and Timmermann and its connection to a geometric problem problem of Rassias and Wagner