Acta Math. Univ. Comenianae 267 Vol. LXXXVIII, 2 (2019), pp. 267–268

GRAPH EMBEDDINGS AND MAPS ON SURFACES PODBANSKE,´ , JULY 30 – AUGUST 4, 2017

The workshop “Graph Embeddings and Maps on Surfaces”, which took place in the Grand Hotel Permon in Podbansk´ein High Tatras in the middle of summer of 2017, was the seventh in the series of GEMS workshops. The series was started in 1994 in Donovaly by Roman Nedela and Martin Skovieraˇ whose aim was to organize a regular gathering of researchers interested in various aspects of the theory of maps and graph embeddings that would by definition be associated with Slovakia and the Slovakian school of (topological) graph theory. The first meeting was followed in 1997 by another one in Bansk´aBystrica, the third meeting took place in 2001 in Bratislava, the fourth in 2005 in Star´aLesn´a,the fifth in 2009 in T´ale,and the sixth in 2013 in the castle of Smolenice. The organizers of these workshops (which always include a subset of the four leaders of the Slovakian topological graph theory group: Roman Nedela, Martin Skoviera,ˇ Stanislav Jendrol’, and Jozef Sir´aˇn)tryˇ to keep the informal character of the original meetings and at the same time bring to Slovakia some of the best researchers from all over the world who present the most up-to-date results, take advantage of the possibility to interact with other participants, and get a chance to visit some of the most beautiful parts of Slovakia. All participants enjoy the lively discussions of new and old research problems, the exchange of information between both individual researchers and international research teams, as well as the new ideas and discoveries. The workshops simultaneously promote a positive image of Slovakian research in the world and Slovakian research in topological graph theory. The main organizers of the seventh workshop in Podbansk´ewere Roman Nedela, Martin Skovieraˇ and Jozef Sir´aˇn.Theˇ 41 participants from thirteen countries and four continents presented 32 talks and engaged in numerous informal discussions. The list of invited speakers included Marston Conder from the University of Auck- land, Robert Jajcay from the Comenius University in Bratislava, Klavdija Kutnar from the University of Primorska in Koper, Cheryl Praeger from the University of Western in , Egon Schulte from the Northeastern University in Boston, and Pablo Spiga from the University of Milano-Bicocca in Milano. The participants were also treated to a hiking trip and a concert of classical music. Instead of contributing to conference proceedings, the participants of GEMS 2017 were asked to submit contributions based on the research presented at the workshop to a regular issue of Acta Mathematica Universitatis Comenianae where

Received June 11, 2019. 268 GEMS 2019 their contributions were subjected to the usual rigorous refereeing process. For- tunately, all submitted and accepted contributions were processed in a timely manner which allowed for their simultaneous publication in the present issue. Al- together, seven articles of this issue are contributed by researchers associated with GEMS 2017. These constitute a representative cross-section of the various areas investigated at the workshop. We wish to thank all of our colleagues who participated in GEMS 2017, and especially those who chose to contribute to Acta Mathematica Universitatis Come- nianae. We look forward to future meetings of GEMS.

Bratislava, summer 2019 Robert Jajcay and Martin Skoviera,ˇ guest editors