filtering and citizens participation in government decision-making process.

The EUGAGER platform will be built upon a suitable set of formally certified primitives which increase transparency while ensuring privacy and security.

Knowledge manipulation. The evolution of the World Wide Web from static content to user-oriented, dynamic services involves numerous opportunities and challenges for information retrieval and filtering. Content based search engines belong to the everyday life and probably pose a big contribution to the success of the web. The more users participate actively in online communities nowadays, the better collaborative approaches may succeed. Personalized search and filtering is possible by absorbing basic social activities such as mouth-to-mouth­ propaganda in online communities instead (or in enhancement) of using strictly content based techniques. A big advantage of collaborative approaches is the possibility to abstract away from the content by using human intelligence in form of ratings to create new (meta-) information, EUGAGER will provide the European community with the necessary platform to do this. The users' ratings also define a profile by which he is comparable to other users. Similarity measures between users can be defined and used for creating a neighbourhood graph and clustering as well.

The user must be able to handle comfortably the high (and growing) amount of content that EUGAGER will contain. Users may add applications, comments and other content which might be too much to browse manually for others. Of course there will be content which is interesting for (nearly) everybody in the European community, but one can still expect applications, documents and other content to only concern a smaller part of the community. The growing of the community is one of the most important aims and it is endangered if users are frustrated by too much content without some kind of help which shows them the content which they are personally interested in.

Getting statistical information on a big community is, in general, very interesting and if the user gets something in return he might be more interested in sharing his knowledge. We can provide the user with more personalized help if he contributes more to the system. On the other hand, this higher contribution leads to more statistical data of the European community. This is a win-win-situation that EUGAGER will provide in trustworthy and secure way.

The anonymous statistics of the system may also help the scientific community to evaluate existing and new recommender systems.

Security. Appropriate security measures are essential prerequisites for e-government platforms, As with any technical system, a system of this kind may be exposed to errors and deliberate or unintended attempts to circumvent security measures. In this context, moreover, the criticality of the subject poses even more key security requirements to be addressed and assured. Attacks need to be prevented and particular attention needs to be paid to possible systematic attacks, as these can particularly affect results and transparency of the entire process, The platform architecture has to be designed to assure an adequate level of security and to guarantee the properties of confidentiality and integrity of information, identity and access control, privacy of users,

In order to cope with security issues in a distributed and evolving scenario, we need flexible specification languages. Usually flexibility and expressiveness come at the cost of complexity and lack of desirable-property enforcement. Often, common properties for specific access control policies may not be satisfied due to unforeseen interactions among rules or sequence of rules and cooperation of agents: this may lead to discrepancy between what the policy authors intend to specify and what they actually formally specified. This motivates the use of formal verification tools to prove required security properties.

Transparency. The main objective of this project is to empower and engage all types of societal groups and communities, enable them to utilize mass-cooperation platforms and allow governments to incorporate their input while safeguarding against misuse. We think that this will be possible through the availability of platforms and tools that are able to prove that they are fully transparent and that allow users to verify how policy-makers take their decisions. Citizens should have the assurance that their inputs are taken into account by their governors, The transparency has to be in some way bidirectional: governors, by their side, should be assured that users' identity is fully verified and no misuse is allowed. In addition, users are always more worried of preserving their privacy and security, and these are the key features that