Smart devices have become one of the fundamental communication and computing devices in people's everyday lives over the past decade. Their various sensors and wireless connectivity have paved the way for a new application area called mobile crowdsensing where sensing services are provided by using the sensor outputs collected from smart devices. A mobile crowdsensing system's service quality heavily depends on the participation of smart device users who probably expect to be compensated in return for their participation. Therefore, mobile crowdsensing applications need incentive mechanisms to motivate such people into participating. In this thesis, we first defined a reverse auction based incentive mechanism for a representative mobile crowdsensing system. Then, we integrated the Vickrey-Clarke- Groves mechanism into the initial incentive mechanism so as to investigate whether truthful bidding would become the dominant strategy in the resulting incentive mechanism. We demonstrated by theoretical analysis that overbidding was the dominant strategy in the base incentive mechanism, whereas truthful bidding was the dominant strategy in the derived incentive mechanism when the VCG mechanism was applicable. Finally, we conducted simulations of both incentive mechanisms in order to measure the fairness of service prices and the fairness of cumulative participant earnings using Jain's fairness index. We observed that both the fairness of service prices and the fairness of cumulative participant earnings were generally better in the derived incentive mechanism when the VCG mechanism was applied. We also found that at least 70% of service requests had fair prices, while between 5% and 85% of participants had fair cumulative earnings in both incentive mechanisms.

Ce travail porte sur les fragments du Discours véritable de Celse, du Contre les chrétiens de Porphyre, du Discours ami de la vérité adressé aux chrétiens d’Hiéroclès et du Contre les Galiléens de Julien. Son but est d’étudier la façon dont ces traités antichrétiens se rattachent à la tradition littéraire de l’Antiquité. Dans une première partie, nous discutons des problèmes liés à l’étude de ces œuvres. Dans une deuxième partie, nous étudions l’emploi polémique des références littéraires chez les polémistes. Une troisième partie est consacrée aux attaques ad hominem contre les personnages bibliques et contre les chrétiens. Enfin, une quatrième partie étudie la forme littéraire de ces œuvres : le choix du titre et du public, mais aussi la structure et le genre littéraire. / This work deals with the fragments of Celsus’ True Discourse, Porphyry’s Against the Christians, Hierocles’ Truthful Discourse to the Christians and Julian’s Against the Galileans. Its purpose is to study the way these anti-Christian treatises use the literary tradition of Antiquity. In the first part, we discuss some problems related to the study of these works. In a second part, we study the polemical use of literary references in these texts. A third part is devoted to ad hominem attacks against biblical characters and against Christians. Finally, a fourth part studies the literary form of these works : the choice of the title and the audience, but also their structure and their literary genre.