International workshop on graphs, semigroups, and semigroup acts

October 10 - October 13, 2017, Berlin


This conference brings together scholars from areas including but not restricted to: categories, semigroups, acts, monoids, algebraic graph theory, and mathematical modelling. In particular, we celebrate the 75th birthday of Ulrich Knauer, whose research over the years has been related to the above topics. The aim is to present and discuss current research in a friendly and intimate setting.

The workshop takes place at the Institute of Mathematics of the Technical University Berlin, Strasse des 17.Juni 136, Berlin. Talks will be in room MA043. Coffee breaks and registration will be in room MA144. Lunch is not included. There are two restaurants in the math building and many restaurants at a close walking distance. The conference dinner will take place Wednesday night at Die Stulle .

group1 group2

More pictures (mostly by Sayan Panma) can be found here.


(For abstracts and more information have a look at the booklet.)

10:45 Coffee and registration
11:15 Opening
11:30 Laszlo Marki: Morita equivalence of semigroups revisited: firm semigroups
12:00 Lunch Break
14:00 Lauri Tart: On Morita equivalence of fair semigroups
14:30 Valdis Laan: Monomorphisms in categories of firm acts
15:00 Coffee
15:30 Sayan Panma: On partially composed property of generalized lexicographic product graphs
16:00 Apirat Wanichsombat: Algebraic properties of the monoids of path of cycles
16:30 Akihiro Yamamura: Combinatorial Designs and One Factorizations of Tripartite Graphs

09:30 Bernhelm Booss-Bavnbek: Cross roads in the process of mathematization exemplified by early astronomy
10:00 Xia Zhang: On injective hulls of S-poset
10:30 Coffee Break
11:00 Alexander Tishchenko: Wreath products of semigroup varieties
11:30 Igor Kozhukhov: On the structure of acts
12:00 Lunch Break
14:00 Stories and anecdotes (slides by Aiso Heinze)
15:00 Coffee
15:30 Vladimir Yaroshevich: On properties of one-value and multi-values mappings which preserve a given binary relation
16:00 Somnuek Worawiset: The class of all semigroups related to semihypergroups of order 2
16:30 Denis Solomatin: On ranks of the planarity of semigroup varieties
19:00 Conference Dinner at Die Stulle

09:30 Tatiana Jajcayova: Combinatorial Methods in Study of Structure of Inverse Semigroups
10:00 Anatoliy Zhuchok: On free products of n-tuple semigroups
10:30 Coffee Break
11:00 Roland Kaschek: A note on the reconstruction conjecture
11:30 Jörg Koppitz: The rank of the semigroup of all order-preserving transformations on a finite fence
12:00 Lunch Break
14:00 Problem session (scribe by Roland Kaschek and Kolja Knauer)
15:00 Coffee
15:30 Rida-E Zenab: Pseudo-generated and pseudo-finite monoids
16:00 Alexander Revyakin: Some problems on matroids

09:30 Victoria Gould: Coherency and purity for monoids
10:00 Yurii Zhuchok: On coregularity of endotopism semigroups of partial equivalence
10:30 Coffee Break
11:00 Ignacio García-Marco: The chomp game on numerical semigroup posets
11:30 Kolja Knauer: Posets from semigroups
12:00 End


Aiso Heinze, Akihiro Yamamura, Alexander Tishchenko, Alexander Revyakin, Anatoliy Zhuchok, Angela Schmitmann gen. Pothmann, Apirat Wanichsombat, Barbara Langfeld, Bernhelm Booss-Bavnbek, Denis Solomatin, Horst Eckhard Gross, Ignacio García-Marco, Igor Kozhukhov, Jörg Koppitz, Kolja Knauer, Laszlo Marki, Lauri Tart, Mariel Orozco, Reinhard Pöschel, Rida-E Zenab, Roland Kaschek, Sayan Panma, Somnuek Worawiset, Stefan Felsner, Tatiana Jajcayova, Ulrich Knauer, Valdis Laan, Victoria Gould, Vladimir Yaroshevich, Yurii Zhuchok, Xia Zhang.

Organizing and scientific committee

Aiso Heinze, Barbara Langfeld, Stefan Felsner, Roland Kaschek, Kolja Knauer, Mariel Orozco.

Practical hints