2000, March – Visiting Researcher, Combinatorial and Computational Mathematics Center,
2001, March Pohang University of Science and Technology, Pohang, The Republic of Korea
2003, February -Visiting Professor, Center for Interdisciplinary Research (ZiF), Bielefeld University,
April Germany
2004, July – Visiting Professor, Michigan Technological University (MTU), Houghton, Michigan, USA
2004, September – Visiting Researcher, Department of Informatics and Computational Biology Unit, Bergen
October University, Norway
2005, March – Visiting Researcher, Mathematisches Forschungsinstitut Oberwolfach, Germany
2005, July – Visiting Professor, School of Mathematics, University of East Anglia, UK
2005, November – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest,
December Hungary
2006, April – Visiting Professor, Institute for Studies in Theoretical Physics and Mathematics (School of Mathematics), Tehran, Islamic Republic of Iran
2006, May – Visiting Researcher, Research Center for Computer Science, Schloss Dagstuhl, Germany
2006, May – Visiting Researcher, Mathematisches Forschungsinstitut Oberwolfach, Germany
2006, November – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest
2007, November – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest
2008, November – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest,
December Hungary
2009, November – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest
2009, December – Visiting Professor, Pusan National University, Pusan, Republic of KOREA
2010, July – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest
2011, March – Visiting Professor, Department of Mathematics, College of Science, Yeungnam University,
2012, February Gyeongsan, The Republic of Korea
2012, May – Visiting Professor, Faculty of Mathematics, Natural Sciences and Information Technologies,
July University of Primorska, Andrej Maruˇsiˇc Institute, Koper, Slovenia
2012, December – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest,
2013, December – Visiting Professor, Renyi Institute of Mathematics, Hungarian Academy of Science, Budapest,
2014, January – Visiting Professor, School of Mathematical Sciences, Tel Aviv University, Israel
2015, January – Visiting Professor, Institute of Mathematics, Academia Sinica, Taipei, Taiwan
2015, March – Visiting Professor, Faculty of Mathematics, Natural Sciences and Information Technologies,
April University of Primorska, UP FAMNIT, Koper, Slovenia
2015, October – Visiting Professor, Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia
2016, May – Visiting Professor, University of Verona, Department of Computer Science, Verona, Italy
2017, March – Visiting Professor, Tohoku University, Graduate School of Information Sciences, Sendai, Japan
2017, March – Visiting Professor, University of Tokyo, Department of Mathematical Sciences, Tokyo, Japan
2017, June – Visiting Professor, Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Koper, Slovenia
2018, March – Visiting Professor, Shanghai Jiao Tong University, Shanghai; University of Science and
April Technology of China, Hefei; China Three Gorges University, Yichang; Central China Normal University, Wuhan; South China University of
Technology, Guangzhou; Northwestern Polytechnical University, Xi’an; Qinghai Normal University, Xinig, China
2018, June, – Visiting Professor, Faculty of Mathematics, Natural Sciences and Information Technologies,
September University of Primorska, Koper, Slovenia
2018, October – Visiting Professor, Sharif University of Technology, Institute for Research in Fundamental Sciences, Tehran, Islamic Republic of Iran
2018, December – Visiting Professor, King Fahd University of Petroleum and Minerals (KFUPM), Department of Mathematics and Statistics, Saudi Arabia
2019, January – Visiting Professor, Pusan National University, Pusan, Republic of Korea
2019, April – Visiting Professor, China Three Gorges University, Yichang, China
2019, June – Visiting Professor, Faculty of Mathematics, Natural Sciences and Information Technologies,
University of Primorska, Koper, Slovenia
2019, August – Visiting Professor, China Three Gorges University, Yichang, China
2020, February – Visiting Professor, Sharif University of Technology, Tehran, Islamic Republic of Iran