CATS staff collaborates actively with various groups all over the world and the staff members frequently visit their collaborators abroad (for instance, P. Cvitanovic is Adjunct Professor at the Rockefeller University two months a year, and P. Alstrøm is a Research Assistant Professor at the Boston University). It is no less important for the Danish research environment that we can bring some of the world's leading experts, post-doctoral fellows and students to Denmark. CATS Center facilitates such exchanges by giving us flexibility in arranging visits with short lead time, as well as helping us send the top Danish students to international schools and research centers.
Europe (in particular France, Russia, Germany, England, Belgium and Denmark) arguably leads the world in the research on nonlinear phenomena and complex systems, and the CATS groups are very active in European collaborative efforts. We already have many EU funded visitors and expect to attract still more EU post-doctoral fellows and Ph.D. students in coming years. Participation in the ``European Network on Nonlinear Physics'', coordinated by G. Nicolis, Brussels, with P. Cvitanovc acting as the Danish representative, strengthens the European role of the CATS Center. Some examples of other current European collaborations: E. Mosekilde and A. Hunding have visited the Brussels under auspices of the EU ERASMUS program. An EU twinning project ``Dynamical and Geometrical Aspects of Correlations near Critical Points" between Copenhagen, Naples, Paris, Nice, and Cologne is coordinated by P. Alstrøm. G. Paladin (Rome) and M.H. Jensen coordinate an EU funded exchange of students and post-doctoral fellows between the nonlinear groups at the Physics Department, Rome University, and the NBI/Nordita group. HCØ-KI participates in a Joint European TEMPUS Project ``Nonlinear dynamics in Chemistry and Biology" together with M. Marek (Prague), G. Nicolis (Brussels), S. Müller (Dortmund), and F. W. Schneider (Würzburg). As a part of the program, P. G. Sørensen and F. Hynne have spent two weeks each in Prague, Ph.D. student J. Kosek (Prague) has worked 3 months at HCØ-KI with quenching experiments, and master degree students T. Møller and M. Ipsen have been on visits for 3 months to Prague.