Petros Belsis Stefanos Gritzalis Sokratis K. Katsikas Optimized Multi-Domain Secure Interoperation using Soft Constraints. 78-85 2006 conf/ifip12/2006aiai AIAI http://dx.doi.org/10.1007/0-387-34224-9_10 db/conf/ifip12/aiai2006.html#BelsisGK06