# Raziskovalni matematični seminar - Arhiv

2020 | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 |

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**Datum in ura**/ Date and time: 24.2.20

**Predavalnica**/ Location: FAMNIT-MP1

**Predavatelj**/ Lecturer: Russ Woodroofe (UP FAMNIT)

**Naslov**/ Title: A New Characterization of Supersolvable Lattices

**Vsebina**/ Abstract:

Stanley introduced _supersolvable lattices_ in the 1970s to describe properties that certain lattices have in common with subgroup lattices of supersolvable groups. In recent work with Stephan Foldes, we have given a new characterization of supersolvable lattices in terms of lattice-theoretic analogues of normal subgroups. Our characterization simplifies and unifies existing literature on this class.

I'll introduce this class of lattices with motivating examples, and compare our characterization with existing ones.

**Datum in ura**/ Date and time: 15.2.20

**Predavalnica**/ Location: FAMNIT-MP1

**Predavatelj**/ Lecturer: Stevan Pilipović & Gradimir V. Milovanović

**Naslov**/ Title: Mathematical Research Seminar sponsored by SASA at UP FAMNIT

**Vsebina**/ Abstract:

10:00 – 10:45: FAMNIT-MP1__Lecturer: __Stevan Pilipović__Title: __*Pseudo-differential operators-some new results.*

Stevan Pilipović is an academician of the Serbian Academy of Sciences and Arts. His research interests include functional analysis, generalized functions and hyperfunctions, pseudo-differential operators, time-frequency analysis, linear and nonlinear equations with singularities, probability theory and stochastic processes.

**11:00 – 11:45: FAMNIT-MP1**__Lecturer:__ Gradimir V. Milovanović __Title: __*Orthogonality in the complex plane and some applications.*

Gradimir V. Milovanović is a full member of the Serbian Academy of Sciences and Arts. His research is motivated by the range of topics among orthogonal polynomials and systems, interpolation theory and numerical analysis.

**Datum in ura**/ Date and time: 10.2.20

**Predavalnica**/ Location: FAMNIT-MP1

**Predavatelj**/ Lecturer: Gábor Korchmáros (Universitá degli Studi della Basilicata, Potenza, Italy)

**Naslov**/ Title: Problems in Euclidean Distance Geometry

**Vsebina**/ Abstract:

Euclidean distance geometry, that is the study of Euclidean geometry based on the concept of distance, is of current interest in several practical applications, such as molecular biology, wireless sensor networks, statics, data visualization and robotics. In this talk, we show how introductory algebraic geometry can be used as an effective tool for the solution of certain problems in Euclidean distance geometry.

**Datum in ura**/ Date and time: 27.1.20

**Predavalnica**/ Location: FAMNIT-MP1

**Predavatelj**/ Lecturer: Meike Hatzel (TU Berlin, Germany)

**Naslov**/ Title: Avoidable paths in graphs

**Vsebina**/ Abstract:

**Datum in ura**/ Date and time: 13.1.20

**Predavalnica**/ Location: FAMNIT-MP1

**Predavatelj**/ Lecturer: Gyula Y. Katona (Budapest University of Technology and Economics, Hungary)

**Naslov**/ Title: Minimally t-Tough Graphs

**Vsebina**/ Abstract:

A graph G is minimally t-tough if the toughness of G is t and the deletion of any edge from G decreases the toughness. Kriesell conjectured that for every minimally1-tough graph the minimum degree δ(G) = 2. It is natural to generalize this for other t values: Every minimally t-tough graph has a vertex of degree ceil(2t). In the present talk we investigate different questions related to this conjecture. The conjecture seems to be hard to prove, so we tried to prove it for some special graph classes. It turned out, that in some cases the conjecture is true because there are very few graphs that satisfy the conditions. On the other hand, we have evidence using complexity theory, that this is not the situation for some other graph classes. Many open questions remain.

This is joint work with Kitti Varga, István Kovács, Dániel Soltész.

**Datum in ura**/ Date and time: 6.1.20

**Predavalnica**/ Location: FAMNIT-MP1

**Predavatelj**/ Lecturer: Nino Bašić (UP FAMNIT)

**Naslov**/ Title: Point-ellipse and some other exotic configurations

**Vsebina**/ Abstract:

In this talk, we introduce point-ellipse configurations and point-conic configurations. We present some of their basic properties and describe two interesting families of balanced point-conic 6-configurations. The construction of the first family is based on Carnot's theorem, whilst the construction of the second family is based on the Cartesian product of two regular polygons. Finally, we investigate a point-ellipse configuration based on the regular 24-cell.

This is joint work with Gábor Gévay, Jurij Kovič and Tomaž Pisanski.