Automorphism groups of Steiner triple systems

If $V$ is a Steiner triple system then there is an integer $N_V$ such that$,$ for $u\ge N_V$ and $u\equiv 1$ or $3$ $($mod$\,6),$ there is a Steiner triple system $U$ on $u$ points having $V$ as an ${\rm Aut} U$-invariant subsystem on which ${\rm Aut} U$ induces ${\rm Aut} V$ and ${\rm Aut} U\cong{\rm Aut} V$

Sustainable coalitions in the commons

It is well known that the non-cooperation among agents harvesting a renewable resource is critical for its sustainable management. The present paper gives insights on the complex balance between coalitions structure, resource state or dynamics and agents’ heterogeneity to avoid bio-economic collapses. A model bringing together coalition games and a viability approach is proposed to focus on the compatibility between bio-economic constraints and an exploited common stock dynamics. It is examined to what extent cooperation promotes sustainability. Based on the Shapley value, a measure of the marginal contribution of the users to the sustainability of the resource is proposed. It suggests that the stability of the grand coalition occurs for large enough stocks. By contrast, for lower levels of resource, the most efficient user plays the role of a dictator.Renewable resource, dynamic game, coalition, maxmin strategy, shapley value, viability kernel

Quelques sanctuaires entre Seine et Meuse sous les Valentiniens et les Théodosiens (364-455 apr. J.-C.) : les apports de la numismatique quantitative

International audienceThe quantification of coin data from sanctuaries occupied under the Valentinians and Theodosians between Seine and Meuse can raise the question of coinage status in late cult sites. The frequency rates show that currency subsequent to 260 AD is in all points similar to currency used at the same time in rural and urban sites. The study of distribution when possible seems to prove that only a small part of coins could be linked to religious activity. However, the numerical data show an important activity on these cult sites between 364 and 378 AD, generally the double of annual loss calculated in the period 260-402, thus providing confirmation of a relative prosperity under the Valentinians. On the other hand, after a decade of limited issues from coin mints between 378 and 388 AD, the following period is less documented, with a drop of 75% in the metal value of finds: to the likely retraction of coin losses may be added a methodological problem connected to the sampling of coins of small module found in layers of the 5th and 6th c.La quantification des données numismatiques issues des sanctuaires occupés sous les Valentiniens et les Théodosiens entre Seine et Meuse permet de poser la question du statut de la monnaie dans les lieux de culte tardifs. Les indices de fréquence montrent que le numéraire postérieur à 260 apr. J.-C. y est en tous points identique à celui utilisé au même moment dans les habitats ruraux ou urbains. L’analyse de la répartition, lorsqu’elle est possible, tend à prouver que seule une faible partie des monnaies pourrait avoir un lien avec l’activité religieuse. Toutefois, les données numériques montrent sur ces lieux de culte une activité importante entre 364 et 378, en général le double des pertes annuelles moyennes calculées sur la période 260-402, confirmant ainsi une relative prospérité sous les Valentiniens. En revanche, après une décennie de faible production des ateliers monétaires entre 378 et 388, la période immédiatement postérieure est moins bien documentée, avec une chute de 75 % de la valeur métallique des trouvailles : à la rétraction probable des pertes de monnaies vient sans doute s’ajouter un problème méthodologique lié au prélèvement du numéraire de petit module présent dans les couches des Ve et VIe s

Robust safety of timed automata

Timed automata are governed by an idealized semantics that assumes a perfectly precise behavior of the clocks. The traditional semantics is not robust because the slightest perturbation in the timing of actions may lead to completely different behaviors of the automaton. Following several recent works, we consider a relaxation of this semantics, in which guards on transitions are widened byΔ>0 and clocks can drift byε>0. The relaxed semantics encompasses the imprecisions that are inevitably present in an implementation of a timed automaton, due to the finite precision of digital clocks. We solve the safety verification problem for this robust semantics: given a timed automaton and a set of bad states, our algorithm decides if there exist positive values for the parametersΔ andε such that the timed automaton never enters the bad states under the relaxed semantic

Antichains for the Automata-Based Approach to Model-Checking

We propose and evaluate antichain algorithms to solve the universality and language inclusion problems for nondeterministic Buechi automata, and the emptiness problem for alternating Buechi automata. To obtain those algorithms, we establish the existence of simulation pre-orders that can be exploited to efficiently evaluate fixed points on the automata defined during the complementation step (that we keep implicit in our approach). We evaluate the performance of the algorithm to check the universality of Buechi automata using the random automaton model recently proposed by Tabakov and Vardi. We show that on the difficult instances of this probabilistic model, our algorithm outperforms the standard ones by several orders of magnitude

Effects of Grain Size and Shape of alumina aggregates on the Sinterability and Thermal Shock Resistance of Refractory Materials

The Concerted European Action on Sustainable Application of REFractories ( is a consortium created to drive sustainable refractory materials and processes in steel production. This project which runs from 2022 2025 seeks to improve the microstructure for increased sustainability and thermo mechanical performances of refractory castables. In this work, different formulations of alumina spinel refractory castables are considered The main objective is to propose a new design for the microstructure of refractory materials with improved thermo mechanical properties by considering • The nature of aggregates ( crystallinity, physical properties • The arrangement of the calcium aluminate phases network (formation temperatures, unique formation mechanisms, location and morphology

La nécropole du haut Moyen Âge du « Clos II » à Buchères (Aube)

Dans le cadre d’une fouille préventive, réalisée en 2009, une nécropole du haut Moyen Âge a été mise au jour à Buchères (Aube). Cent trente-neuf structures funéraires y ont été dénombrées. L’étude typo-chronologique du mobilier ainsi que les datations radiocarbone permettent de dater l’utilisation de cette nécropole entre la fin du VIe et le tout début du XIe siècle. Le mobilier funéraire exhumé témoigne de la pratique de l’inhumation habillée et du dépôt d’objets dans les sépultures.As part of a rescue archaeology operation carried out in 2009, a medieval graveyard was discovered in Buchères (Aube). One hundred and thirty nine graves were excavated. The typo-chronological study of the funeral deposit and the radiocarbon dating of the skeletons date this site from the end of the VIth to the early beginning of the XIth century. The funeral deposit proves that both dressed burials and artefact deposits were practiced (Nous remercions le Dr. John Sills (Oxford Institute for Archæology) pour sa révision du résumé).Im Rahmen einerPräventivgrabung wurde 2009 in Buchères (Département Aube) eine frühmittelalterliche Nekropole mit 139 Gräbern freigelegt. Die typologische und chronologische Untersuchung der Grabbeigaben und die Radiokarbondaten lassen eine Nutzung dieser Nekropole zwischen dem Ende des 6. und den ersten Jahren des 11. Jahrhunderts erkennen. Die Grabausstattung zeugt von der Sitte die Toten bekleidet beizusetzen und ihnen Beigaben mitzugeben

Climate-dependent scenarios of land use for biodiversity and ecosystem services in the New Aquitaine region

The synergies and trade-offs between human well-being, biodiversity, and ecosystem services are under debate for the design of more sustainable public policies. In that perspective, there is a need of quantitative methods to compare all these outcomes under alternative policy scenarios. The present paper provides scenarios at the horizon 2053 for the New-Aquitaine region in France. They rely on spatio-temporal models derived from individual land-use choices under climate change. The models are estimated at the national level from 1993-2003 fine-scale data. We focus on farming, forestry, and urban land-uses along with bird biodiversity scores and a basket of ecosystem services namely carbon sink intensity, forest recreation, and water pollution. A ‘climate-economic adaptation’ scenario shows that climate-induced land-use worsens the negative effects of climate change on biodiversity and several ecosystem services in the long run as compared to a ‘status quo’ scenario. Another scenario with an incentive policy, based on a flat payment for pastures, slightly mitigates these negative impacts on biodiversity and water pollution. However, this turns out to be detrimental for other ecosystem services. This result confirms that the design of sustainable policies can not be limited to uniform strategies and should account for the complexity of ecosystem management