Visiting Positions

2004: 4 months, visiting professor at University of Kyoto.

2003:  1 week, visiting researcher, Mathematisches Institut, Universität München.

2002: 1 months, distinguished visitor,  Department of Mathematics, Texas A&M University

2001: 2 weeks, visiting researcher, Lamar University at Beaumont and Texas A&M University.

2000: 2 weeks, visiting researcher, Lamar University at Beaumont, Texas

1999: 1 month, visiting researcher, GMD, Institute for Algorithms, Bonn, Germany.

1999: 1 week , visiting researcher, University of Debrecen, Institute of Mathematics, Hungary.

1999: 2 weeks , visiting researcher, University of Timisoara, Institute of Mathematics, Rumania.

1998: 2 weeks , visiting professor, Universidad de Oriente, Santiago, Cuba.

1998: 1 week , visiting researcher, University of Wales at Bangore, UK.

1997: 1 month, visiting researcher, GMD, Institute for Algorithms, Bonn, Germany.

1997: 2 months, JSPS (Japanes Society for the Promotion of Science) fellow, University of Tsukuba, SCORE Research Group, Japan.

1997: 1 week, visiting professor for international graduate program, University of Hiroshima, Dept. of Computer Science, Japan.

1996/97: 5 months, TARA (Tsukuba Advanced Research Alliance) visiting professor, University of Tsukuba, Dept. of Information Sciences, Japan.

1996: 1 month, visiting researcher, Wolfram Research International, Champaign, Illinois, USA.

1996: 1 month, visiting professor, Australian National University, Canberra, Australia.

1991: 1 month, visiting professor, University of Pisa, Computer Science Dept., Italy.

1987: 6  weeks, visiting professor, University of Vienna, Institute for Stastistics and Applied Informatics, Austria.

1987: 1 month, visiting researcher, Research Institute ICOT, Tokyo, Japan.

1987: 1 month, visiting researcher, Research Institute RIKEN, Wako-Shi, Japan.

1986: 2 months, visiting researcher, Ohio State University, Dept. of Computer Science, USA.

1986: 2 months, visiting researcher, Soft Warehouse, Honolulu, Hawaii, USA.

1986: 2 months, visiting researcher, University of Delaware, Dept. of Computer and Information Sciences, USA.

1984: 1 month, visiting researcher, University of Leipzig, Mathematical Center, Germany.

1983: 1 month, visiting researcher, University of Genova, Dept. of Computer Science, Italy.

1982: 2 months, visiting researcher, University of Wisconsin at Madison, Dept. of Computer Science, USA.

1982: 6 months, visiting professor, University of Delaware, Dept. of Computer and Information Sciences, USA.

1970/1971: 1 year, visiting researcher, Joint Institute for Nuclear Research, Dubna (Moscow), Russia.