President of:

• Deutsche Gesellschaft für Unternehmensforschung (DGU), 1968-1970
• Deutsche Gesellschaft für Operations Research (DGOR), 1971-1975
• European Association of Operational Research Societies (EURO), 1975-1978
• The Institute of Management Science (TIMS), Council Member 1977-1979
• International Federation of Operational Research Societies (IFORS),
  Vice-President 1980-1983
• IFSA (International Fuzzy Systems Association), President 1984-1987
• The International Honorary Society OMEGA RHO, European Director 1982-
• CCM, Computer and Cognitive Mapping, Santa Barbara, California 93103, USA, Director
• Research Fellow, Fuzzy Systems and Knowledge Engineering, Institute of Guang Zhou University, China
• VWI (Verband der Wirtschaftsingenieure),
  1987-1989 Vice-President
  1989 - 1993 President
• EEMA (European Engineering and Management Association)
  1991-1993 Founding President
• "Fuzzy-Initiative Nordrhein-Westfalen"
  1991 - 1996 Chairman
• ERUDIT (European Network of Excellence, DG III-Industry, ESPRIT) coordinator and Chairman of the steering committee since 1995 - 2000

Chairman, Organizer or Co-Chairman of:

• Annual Conference of the  "Arbeitskreis Operational Research" (AKOR), 1968
• Annual Conference of  DGOR:
• 1971 Bochum
• 1972 Hamburg
• 1973 Karlsruhe
• 1974 Würzburg
• 1975 Interlaken (Switzerland)
• 1976 Nürnberg
• First European Conference on Operations Research, 1975, Brussels
• Joint TIMS-EURO Conferene, 1977, Athens
• NATO Advanced Research Institute on Search Theory, 1979, Portugal
• Hamburg OR-Software Exhibition (in the Framework of the IFORS-Conferene), 1981, Hamburg
• Symposium on Fuzzy Sets in OR, Artificial Intelligence and Expert Systems, Cambridge, 1984
• First World Congress of the International Fuzzy Systems Association,
  Palma de Mallorca (Spain), 1985
• NATO Advanced Teaching Institute on Fuzzy Set Theory & Applications,
  Louvain-La-Neuve (Belgium), 1985
• NATO Advanced Teaching Institute on Mathematical Models for Decision Support, Val d`Isere (France), 1987
• XI European Operations Research Conference, Aachen 1991
• EUFIT 93: European Conference for Fuzzy and Intelligent Technologies,
  Aachen 1993
• 1. Int. Workshop on "Fuzzy Logic in Nuclear Science" (FLINS), Mol (Belgium) 1994
• EUFIT 94: European Conference for Intelligent Technologies, Aachen 1994
• EUFIT 95: European Conference for Intelligent Technologies, Aachen 1995
• IFSA Conference Sao Paulo (Brazil) 1995, Honorary Vice-Chair
• ISUMA/NAFIPS, Third Int. Symp. Uncertainty College Park, USA, 1995,
  Co-Chairman
• EUFIT 96: European Conference for Intelligent Technologies, Aachen 1996
• EUFIT 97: European Conference for Intelligent Technologies, Aachen 1997
• EUFIT 98: European Conference for Intelligent Technologies, Aachen 1998
• EUFIT 99: European Conference for Intelligent Technologies, Aachen 1999
• Honorary Chairman: Neuro Fuzzy 2002, Havana (Cuba)

Associations:

Member of AEA, TIMS, ORSA, APICS, AIIE, DGOR (Deutsche Gesellschaft für Operations Research), IFSA, GI (German Comp. Sc.Ass.)

Functions RWTH-Aachen:

• Vertrauensdozent Evgl. Studienwerk Villigst: 1969-1990
• Wahlsenator der Fakultät :1969-1970; 1974-75; 1985- 1987
• Abteilungsleiter der Fachabt. Für Wirtschaftswissenschaften: 1971-1973
• Dekan der Fakultät für Wirtschaftswissenschaften: 1988-1991
• Fakultätsvertreter im Senatsauschuß für das Bauwesen
• Mitglied und ab 1994 Leiter des Senatsausschusses für das Rechenzentrum
  bis 1999
• Vorsitzender des Ehrungsausschusses der Fak.für Wirtschaftswissenschaften
• Vorsitzender des Prüfungsausschusses für das Aufbaustudium Operations Research: 1972-1999