These topics are transversal to Digiteo in the sense that aspects of several of the five main themes above are required to lead successful research in these areas. Such interactions are likely to take place via the choice of a few theoretical and applicative challenges, guided by some thorough analysis of the specific competences and resources in Digiteo. Such challenges should be the basis of original and highly advanced research projects leading to significant scientific breakthrough. Two such projects have been installed in Digiteo during the two last years, but it seems likely that the topics considered here are sufficiently open and hot for benefiting of more interactions, both inside the topic itself and outside it. Digiteo will continue to look for, suggest and encourage such interactions, so that they take shape and lead to fruitful projects.