Interactive Epistemology and Reasoning: On the Foundations of Game Theory

Game theory describes and analyzes strategic interaction. It is usually distinguished between static games, which are strategic situations in which the players choose only once as well as simultaneously, and dynamic games, which are strategic situations involving sequential choices. In addition, dynamic games can be further classified according to perfect and imperfect information. Indeed, a dynamic game is said to exhibit perfect information, whenever at any point of the game every player has full informational access to all choices that have been conducted so far. However, in the case of imperfect information some players are not fully informed about some choices. Game-theoretic analysis proceeds in two steps. Firstly, games are modelled by so-called form structures which extract and formalize the significant parts of the underlying strategic interaction. The basic and most commonly used models of games are the normal form, which rather sparsely describes a game merely in terms of the players' strategy sets and utilities, and the extensive form, which models a game in a more detailed way as a tree. In fact, it is standard to formalize static games with the normal form and dynamic games with the extensive form. Secondly, solution concepts are developed to solve models of games in the sense of identifying the choices that should be taken by rational players. Indeed, the ultimate objective of the classical approach to game theory, which is of normative character, is the development of a solution concept that is capable of identifying a unique choice for every player in an arbitrary game. However, given the large variety of games, it is not at all certain whether it is possible to device a solution concept with such universal capability. Alternatively, interactive epistemology provides an epistemic approach to game theory of descriptive character. This rather recent discipline analyzes the relation between knowledge, belief and choice of game-playing agents in an epistemic framework. The description of the players' choices in a given game relative to various epistemic assumptions constitutes the fundamental problem addressed by an epistemic approach to game theory. In a general sense, the objective of interactive epistemology consists in characterizing existing game-theoretic solution concepts in terms of epistemic assumptions as well as in proposing novel solution concepts by studying the game-theoretic implications of refined or new epistemic hypotheses. Intuitively, an epistemic model of a game can be interpreted as representing the reasoning of the players. Indeed, before making a decision in a game, the players reason about the game and their respective opponents, given their knowledge and beliefs. Precisely these epistemic mental states on which players base their decisions are explicitly expressible in an epistemic framework. In this PhD thesis, we consider an epistemic approach to game theory from a foundational point of view. In Chapter 1, basic game-theoretic notions as well as Aumann's epistemic framework for games are expounded and illustrated. Also, Aumann's sufficient conditions for backward induction are presented and his conceptual views discussed. In Chapter 2, Aumann's interactive epistemology is conceptually analyzed. In Chapter 3, which is based on joint work with Conrad Heilmann, a three-stage account for dynamic games is introduced and a type-based epistemic model is extended with a notion of agent connectedness. Then, sufficient conditions for backward induction are derived. In Chapter 4, which is based on joint work with Jérémie Cabessa, a topological approach to interactive epistemology is initiated. In particular, the epistemic-topological operator limit knowledge is defined and some implications for games considered. In Chapter 5, which is based on joint work with Jérémie Cabessa and Andrés Perea, Aumann's impossibility theorem on agreeing to disagree is revisited and weakened in the sense that possible contexts are provided in which agents can indeed agree to disagree.

L'imaginaire du sabbat. Edition critique des textes les plus anciens (1430 c.- 1440 c.)

Résumé : Une importante littérature rédigée dans les années trente et quarante du XVe siècle décrit et définit pour la première fois et avec force détails, ce que l'on peut appeler l'imaginaire du sabbat des sorciers. En l'espace d'une décennie et dans un cadre territorial restreint - l'arc alpin qui va du Dauphiné au Simmental en passant par le Valais, le val d'Aoste et le Pays de Vaud, le fantasme du sabbat des sorciers et sorcières se met en place, avant de s'installer dans l'horizon mental de l'Europe pendant plusieurs siècles. Les textes écrits, qui rendent compte de l'émergence de cet imaginaire si lourd de conséquences pour l'histoire de l'Europe à la fin du Moyen Age et pendant une grande partie de l'époque moderne, ne sont pas nombreux. Ils proviennent de cinq auteurs : le dominicain allemand Jean Nider, deux laïcs (le chroniqueur lucernois Hans Fründ et le juge dauphinois Claude Tholosan), le chanoine de Lausanne Martin Le Franc et l'auteur anonyme des Errores gazariorum. En offrant une édition critique, une traduction française et une analyse détaillée de ces cinq textes, le présent ouvrage permet de saisir leur véritable contribution à la genèse de l'imaginaire du sabbat des sorciers et des sorcières.

Quantitative ultrasound for the detection and management of osteoporosis.

Quantitative ultrasound (QUS) appears to be developing into an acceptable, low-cost and readily-accessible alternative to dual X-ray absorptiometry (DXA) measurements of bone mineral density (BMD) in the detection and management of osteoporosis. Perhaps the major difficulty with their widespread use is that many different QUS devices exist that differ substantially from each other, in terms of the parameters they measure and the strength of empirical evidence supporting their use. But another problem is that virtually no data exist outside of Caucasian or Asian populations. In general, heel QUS appears to be most tested and most effective. Some, but not all heel QUS devices are effective assessing fracture risk in some, but not all populations, the evidence being strongest for Caucasian females > 55 years old, though some evidence exists for Asian females > 55 and for Caucasian and Asian males > 70. Certain devices may allow to estimate the likelihood of osteoporosis, but very limited evidence exists supporting QUS use during the initiation or monitoring of osteoporosis treatment. Likely, QUS is most effective when combined with an assessment of clinical risk factors (CRF); with DXA reserved for individuals who are not identified as either high or low risk using QUS and CRF. However, monitoring and maintenance of test and instrument accuracy, precision and reproducibility are essential if QUS devices are to be used in clinical practice; and further scientific research in non-Caucasian, non-Asian populations clearly is compulsory to validate this tool for more widespread use.

Time-Course In Vivo Trafficking Pattern and Effector Function of Donor-Specific Regulatory T Cells in Response to an Allograft.

Background: Experimental data have suggested that adoptive transfer of CD4+CD25+Foxp3+ regulatory T cells (Tregs), capable of controlling immune responses to specifi c auto- or alloantigens, could be used as a therapeutic strategy to promote specifi c tolerance in T-cell mediated diseases and in organ transplantation (Tx). However, before advocating the application of immunotherapy with Tregs in Tx, we need to improve our understanding of their in vivo homeostasis, traffi cking pattern and effector function in response to alloantigens. Methods : Donor-antigen specifi c murine Tregs were generated and characterized in vitro following our described protocols. Using an adoptive transfer and skin allotransplantation model, we have analyzed the in vivo expansion and homing of fl uorescent-labeled effector T cells (Teff) and Tregs, at different time-points after Tx, using fl ow-cytometry as well as fl uorescence microscopy techniques. Results: Tregs expressed CD62L, CCR7 and CD103 allowing their homing into lymphoid and non-lymphoid tissues (gut, skin) after intravenous injection. While hyporesponsive to TCR stimulation in vitro, transferred Tregs survived, migrated to secondary lymphoid organs and preferentially expanded within the allograft draining lymph nodes. Furthermore, Foxp3+ cells could be detected inside the allograft as early as day 3-5 after Tx. At a much later time-point (day 60 after Tx), graft-infi ltrating Foxp3+ cells were also detectable in tolerant recipients. When transferred alone, CD4+CD25- Teff cells expanded within secondary lymphoid organs and infi ltrated the allograft by day 3-5 after Tx. The co-transfer of Tregs limited the expansion of alloreactive Teff cells as well as their recruitment into the allograft. The promotion of graft survival observed in the presence of Tregs was in part mediated by the inhibition of the production of effector cytokines by CD4+CD25- T cells. Conclusion: Taken together, our results suggest that the suppression of allograft rejection and the induction of Tx tolerance are in part dependant on the alloantigendriven homing and expansion of Tregs. Thus, the appropriate localization of Tregs may be critical for their suppressive function in vivo.

Can the trabecular bone score be considered as a major clinical risk factor of osteoporotic fractures? A meta-like analysis.

To have an added value over BMD, a CRF of osteoporotic fracture must be predictable of the fracture, independent of BMD, reversible and quantifiable. Many major recognized CRF exist. Out of these factors many of them are indirect factor of bone quality. TBS predicts fracture independently of BMD as demonstrated from previous studies. The aim of the study is to verify if TBS can be considered as a major CRF of osteoporotic fracture. Existing validated datasets of Caucasian women were analyzed. These datasets stem from different studies performed by the authors of this report or provided to our group. However, the level of evidence of these studies will vary. Thus, the different datasets were weighted differently according to their design. This meta-like analysis involves more than 32000 women (≥50years) with 2000 osteoporotic fractures from two prospective studies (OFELY&MANITOBA) and 7 cross-sectional studies. Weighted relative risk (RR) for TBS was expressed for each decrease of one standard deviation as well as per tertile difference (TBS=1.300 and 1.200) and compared with those obtained for the major CRF included in FRAX®. Overall TBS RR obtained (adjusted for age) was 1.79 [95%CI-1.37-2.37]. For all women combined, RR for fracture for the lowest compared with the middle TBS tertile was 1.55[1.46-1.68] and for the lowest compared with the highest TBS tertile was 2.8[2.70-3.00]. TBS is comparable to most of the major CRF and thus could be used as one of them. Further studies have to be conducted to confirm these first findings.

Quantitative ultrasound of the heel and fracture risk assessment: an updated meta-analysis.

Meta-analysis of prospective studies shows that quantitative ultrasound of the heel using validated devices predicts risk of different types of fracture with similar performance across different devices and in elderly men and women. These predictions are independent of the risk estimates from hip DXA measures.Introduction Clinical utilisation of heel quantitative ultrasound (QUS) depends on its power to predict clinical fractures. This is particularly important in settings that have no access to DXA-derived bone density measurements. We aimed to assess the predictive power of heel QUS for fractures using a meta-analysis approach.Methods We conducted an inverse variance random effects meta-analysis of prospective studies with heel QUS measures at baseline and fracture outcomes in their follow-up. Relative risks (RR) per standard deviation (SD) of different QUS parameters (broadband ultrasound attenuation [BUA], speed of sound [SOS], stiffness index [SI], and quantitative ultrasound index [QUI]) for various fracture outcomes (hip, vertebral, any clinical, any osteoporotic and major osteoporotic fractures) were reported based on study questions.Results Twenty-one studies including 55,164 women and 13,742 men were included in the meta-analysis with a total follow-up of 279,124 person-years. All four QUS parameters were associated with risk of different fracture. For instance, RR of hip fracture for 1 SD decrease of BUA was 1.69 (95% CI 1.43-2.00), SOS was 1.96 (95% CI 1.64-2.34), SI was 2.26 (95%CI 1.71-2.99) and QUI was 1.99 (95% CI 1.49-2.67). There was marked heterogeneity among studies on hip and any clinical fractures but no evidence of publication bias amongst them. Validated devices from different manufacturers predicted fracture risks with similar performance (meta-regression p values > 0.05 for difference of devices). QUS measures predicted fracture with a similar performance in men and women. Meta-analysis of studies with QUS measures adjusted for hip BMD showed a significant and independent association with fracture risk (RR/SD for BUA = 1.34 [95%CI 1.22-1.49]).Conclusions This study confirms that heel QUS, using validated devices, predicts risk of different fracture outcomes in elderly men and women. Further research is needed for more widespread utilisation of the heel QUS in clinical settings across the world.

Trabecular Bone Score Helps Classifying Women At Riskof Fracture Prospectively In The Ofely Study

Objectives: Trabecular Bone Score (TBS, Med-Imaps, France) is an index of bone microarchitecture calculated from antero-posterior spine DXA scan and reported to be associated with fracture in prior case-control studies and in a large prospective study with the Prodigy DXA device. Our aim was to assess the ability of TBS to predict incident fracture and improve the classification of fracture prospectively in the OFELY study.Materials/Methods: TBS was assessed in 564 postmenopausal women (66±8 years old) from the OFELY cohort, who had a spine DXA scan (QDR 4500A, Hologic, USA) between year 2000 and 2001. During a mean follow up of 7.8±1.3 years, 94 women sustained a fragility fracture.Results: At the time of baseline DXA scan, women with incident fracture were significantly older (70±9 vs. 65± 8 years), had a lower spine BMD (T-score: −1.9±1.2 vs. −1.3±1.3, p<0.001) and spine TBS (−3.1%, p<0.001) than women without incident fracture. After adjustment for age, BMI and the presence of prevalent fracture, the magnitude of fracture prediction was similar for spine BMD (OR=1.42 [1.11;1.82] per SD decrease [95% CI]) and TBS (OR=1.34 [1.04;1.74]) but the combination of TBS and spine BMD did not improve fracture prediction. Spine BMD and TBS were both correlated with age (respectively r=−0.17 and −0.49, p<0.001) and correlated together with 39% of TBS explained by spine BMD (r=0.63, p<0.001). When using the WHO classification, 38% of the fractures occurred in osteoporotic (fracture rate=29%), 47% in osteopenic (fracture rate=16%) and 15% in women with T-score >−1 (fracture rate=9%). By classifying our population in tertiles of TBS, we found that 47% of the fractures occurred in the lowest tertile of TBS (fracture rate=23%) and 39% of the fracture that occurred in osteopenic women were in the lowest tertile of TBS.Conclusions: Spine BMD and TBS predicted fractures equally well. The addition of TBS to spine BMD added only limited information on fracture risk prediction in our cohort when considering the all range of BMD. Nevertheless combining the osteopenic T-score and the lowest TBS helped defining a subset of osteopenic women at higher risk of fracture.Disclosure of Interest: None declared.

Bone microarchitecture assessed by TBS predicts osteoporotic fractures independent of bone density: The manitoba study.

The measurement of BMD by dual-energy X-ray absorptiometry (DXA) is the "gold standard" for diagnosing osteoporosis but does not directly reflect deterioration in bone microarchitecture. The trabecular bone score (TBS), a novel gray-level texture measurement that can be extracted from DXA images, correlates with 3D parameters of bone microarchitecture. Our aim was to evaluate the ability of lumbar spine TBS to predict future clinical osteoporotic fractures. A total of 29,407 women 50 years of age or older at the time of baseline hip and spine DXA were identified from a database containing all clinical results for the Province of Manitoba, Canada. Health service records were assessed for the incidence of nontraumatic osteoporotic fracture codes subsequent to BMD testing (mean follow-up 4.7 years). Lumbar spine TBS was derived for each spine DXA examination blinded to clinical parameters and outcomes. Osteoporotic fractures were identified in 1668 (5.7%) women, including 439 (1.5%) spine and 293 (1.0%) hip fractures. Significantly lower spine TBS and BMD were identified in women with major osteoporotic, spine, and hip fractures (all p < 0.0001). Spine TBS and BMD predicted fractures equally well, and the combination was superior to either measurement alone (p < 0.001). Spine TBS predicts osteoporotic fractures and provides information that is independent of spine and hip BMD. Combining the TBS trabecular texture index with BMD incrementally improves fracture prediction in postmenopausal women. © 2011 American Society for Bone and Mineral Research.

Mls--a retrovirus exploits the immune system.

The identity of minor lymphocytes stimulating (Mls) antigens, endogenous superantigens that can activate, or induce the deletion of, large portions of the T-cell repertoire, has recently been revealed: they are encoded by mouse mammary tumor viruses (MMTV) that have integrated into the germ line as DNA proviruses. As Hans Acha-Orbea and Ed Palmer point out, Mls-mediated modulation may be only the tip of the retrovirus iceberg; already murine leukemia virus (MuLV), with similar superantigen properties, has been discovered.

Art. "Gütergemeinschaft"

(Résumé de l'ouvrage) Die RGG4 bietet in 15 665 Artikeln und Teilartikeln einen fundierten Überblick über Religion und Religionen, wie sie gelebt und gedacht wurden und werden. Sie bietet den neuesten Forschungsstand, dargestellt von 3 972 ausgewiesenen Kennern der jeweiligen Materie aus 74 Ländern. Die RGG4 führt die Tradition der ersten drei Auflagen fort: Aus der Mitte des evangelischen Glaubens ist weit mehr als die Theologie im Blick, nach deren Kriterien wird aber gewichtet.Die RGG4 erschließt die Themen in Form von biographischen Artikeln, Länder-, Orts-, Begriffs- und Ereignisartikeln sowie Artikeln über Gruppierungen und Institutionen. Knappe Definitionsartikel und Querverweise erleichtern die schnelle Information. Ausführliche Reihenartikel behandeln Stichworte wie "Abendmahl" oder "Christentum" aus vielerlei Perspektiven. Die RGG4 ist durch die Artikelvielfalt und die detailgenaue Darstellung ein Nachschlagewerk; zugleich ist sie eine Lehr- und Repetitionsbibliothek. Sie bringt mit einem ausgesucht lesbaren Schriftbild ein Maximum an Information auf einer Seite. Die acht Bände der RGG4 decken jeweils ganze Buchstaben ab. Der das Werk abschließende Registerband ermöglicht den Zugang zu dem in der RGG4 enthaltenen Wissen nach noch spezielleren Fragestellungen wie beispielsweise Namen und Stichworten, die keinen Haupteintrag haben. Selbstverständlich ist die RGG4 auf alterungsbeständigem Papier gedruckt, solide fadengeheftet und in Buckramleinen gebunden. Die RGG4 erhielt von der Stiftung Buchkunst die Auszeichnung "Eines der schönsten Bücher 1998. Vorbildlich gestaltet in Satz, Druck, Bild und Einband."

Art. "Hellenisten"

(Résumé de l'ouvrage) Die RGG4 bietet in 15 665 Artikeln und Teilartikeln einen fundierten Überblick über Religion und Religionen, wie sie gelebt und gedacht wurden und werden. Sie bietet den neuesten Forschungsstand, dargestellt von 3 972 ausgewiesenen Kennern der jeweiligen Materie aus 74 Ländern. Die RGG4 führt die Tradition der ersten drei Auflagen fort: Aus der Mitte des evangelischen Glaubens ist weit mehr als die Theologie im Blick, nach deren Kriterien wird aber gewichtet.Die RGG4 erschließt die Themen in Form von biographischen Artikeln, Länder-, Orts-, Begriffs- und Ereignisartikeln sowie Artikeln über Gruppierungen und Institutionen. Knappe Definitionsartikel und Querverweise erleichtern die schnelle Information. Ausführliche Reihenartikel behandeln Stichworte wie "Abendmahl" oder "Christentum" aus vielerlei Perspektiven. Die RGG4 ist durch die Artikelvielfalt und die detailgenaue Darstellung ein Nachschlagewerk; zugleich ist sie eine Lehr- und Repetitionsbibliothek. Sie bringt mit einem ausgesucht lesbaren Schriftbild ein Maximum an Information auf einer Seite. Die acht Bände der RGG4 decken jeweils ganze Buchstaben ab. Der das Werk abschließende Registerband ermöglicht den Zugang zu dem in der RGG4 enthaltenen Wissen nach noch spezielleren Fragestellungen wie beispielsweise Namen und Stichworten, die keinen Haupteintrag haben. Selbstverständlich ist die RGG4 auf alterungsbeständigem Papier gedruckt, solide fadengeheftet und in Buckramleinen gebunden. Die RGG4 erhielt von der Stiftung Buchkunst die Auszeichnung "Eines der schönsten Bücher 1998. Vorbildlich gestaltet in Satz, Druck, Bild und Einband."

Le dialogisme intertextuel des contes des Grimm

Loin d'être « purement allemands », nombre de contes des Grimm réécrivent les contes français largement diffusés en Allemagne au 18e siècle en les « reconfigurant » selon leurs propres paradigmes esthétiques et idéologiques. L'étude introductive de la comparatiste Ute Heidmann montre que ce dialogisme européen est resté peu exploré en raison d'une « scénographie en trompe-l'oeil » qui les présente comme issus du « terroir » hessois. Toutefois, les notes des Grimm (constituées en volume autonome dès 1822), dont une partie importante est traduite et commentée ici pour la première fois en français par Loreto Núñez, indiquent ces intertextes tout en les faisant passer pour des « correspondances » dues à une origine commune. L'étude de Jean Mainil retrace le dialogue intertextuel de Rapunzel (Raiponce) avec Persinette de La Force et Petrosinella de Basile. Les cinq études suivantes de Cyrille François, Nathalie Prince, Pascale Auraix-Jonchière, Jean-Michel Adam et Marcio Venício Barbosa retracent les dialogues intertextuels que les contes des Grimm, eux-mêmes fondamentalement intertextuels, ont sollicité à leur tour dans des textes du 19e et du 20e siècle. Elles montrent comment Hans-Christian Andersen, Jean Lorrain (dont l'étonnant conte Neigefleur est reproduit à la suite de l'étude de Nathalie Prince), Robert Walser, Henry Pourrat et les écrivains brésiliens Millôr Ferandes, Mario Prata, Chico Buarque et Guimarães Rosa inventent de nouvelles formes et des procédés intertextuels originaux en réponse aux contes des Grimm en créant de nouveaux contes originaux comme l'avaient fait les Grimm eux-mêmes en réponse aux narrateurs français. Dans les Mélanges, Veronica Bonanni prolonge ce dossier par une étude consacrée à la traduction par Collodi de L'Oiseau bleue de Marie-Catherine d'Aulnoy, qui procède également d'un véritable dialogue intertextuel.