Collaboration allows integrating intellectual resources and knowledge from all participants in order to achieve individual or collective goals. With the help of informational environments, we can better organize, realize and record collaboration. During interactions among users in such environments, each activity produces a set of traces. Such traces are recorded and classified, based on a model of traces and can be exploited to improve collaboration. In this article, we propose a semantic model of traces and analyze classified traces by means of TF-IDF. We exploit the results to offer users recommendations and decision aid.