Decidability Results for Multi-objective Stochastic Games

We study stochastic two-player turn-based games in which the objective of one player is to ensure several infinite-horizon total reward objectives, while the other player attempts to spoil at least one of the objectives. The games have previously been shown not to be determined, and an approximation algorithm for computing a Pareto curve has been given. The major drawback of the existing algorithm is that it needs to compute Pareto curves for finite horizon objectives (for increasing length of the horizon), and the size of these Pareto curves can grow unboundedly, even when the infinite-horizon Pareto curve is small. By adapting existing results, we first give an algorithm that computes the Pareto curve for determined games. Then, as the main result of the paper, we show that for the natural class of stopping games and when there are two reward objectives, the problem of deciding whether a player can ensure satisfaction of the objectives with given thresholds is decidable. The result relies on intricate and novel proof which shows that the Pareto curves contain only finitely many points. As a consequence, we get that the two-objective discounted-reward problem for unrestricted class of stochastic games is decidable.Comment: 35 page

Robust Multidimensional Mean-Payoff Games are Undecidable

Mean-payoff games play a central role in quantitative synthesis and verification. In a single-dimensional game a weight is assigned to every transition and the objective of the protagonist is to assure a non-negative limit-average weight. In the multidimensional setting, a weight vector is assigned to every transition and the objective of the protagonist is to satisfy a boolean condition over the limit-average weight of each dimension, e.g., \LimAvg(x_1) \leq 0 \vee \LimAvg(x_2)\geq 0 \wedge \LimAvg(x_3) \geq 0. We recently proved that when one of the players is restricted to finite-memory strategies then the decidability of determining the winner is inter-reducible with Hilbert's Tenth problem over rationals (a fundamental long-standing open problem). In this work we allow arbitrary (infinite-memory) strategies for both players and we show that the problem is undecidable

Multitask Efficiencies in the Decision Tree Model

In Direct Sum problems [KRW], one tries to show that for a given computational model, the complexity of computing a collection of finite functions on independent inputs is approximately the sum of their individual complexities. In this paper, by contrast, we study the diversity of ways in which the joint computational complexity can behave when all the functions are evaluated on a common input. We focus on the deterministic decision tree model, with depth as the complexity measure; in this model we prove a result to the effect that the 'obvious' constraints on joint computational complexity are essentially the only ones. The proof uses an intriguing new type of cryptographic data structure called a `mystery bin' which we construct using a small polynomial separation between deterministic and unambiguous query complexity shown by Savicky. We also pose a variant of the Direct Sum Conjecture of [KRW] which, if proved for a single family of functions, could yield an analogous result for models such as the communication model.Comment: Improved exposition based on conference versio

Melt block copolymerization of ε-caprolactone and L-lactide

AB block copolymers of ε-caprolactone and (L)-lactide could be prepared by ring-opening polymerization in the melt at 110°C using stannous octoate as a catalyst and ethanol as an initiator provided ε-caprolactone was polymerized first. Ethanol initiated the polymerization of ε-caprolactone producing a polymer with ε-caprolactone derived hydroxyl end groups which after addition of L-lactide in the second step of the polymerization initiated the ring-opening copolymerization of L-lactide. The number-average molecular weights of the poly(ε-caprolactone) blocks varied from 1.5 to 5.2 × 103, while those of the poly(L-lactide) blocks ranged from 17.4 to 49.7 × 103. The polydispersities of the block copolymers varied from 1.16 to 1.27. The number-average molecular weights of the polymers were controlled by the monomer/hydroxyl group ratio, and were independent on the monomer/stannous octoate ratio within the range of experimental conditions studied. When L-lactide was polymerized first, followed by copolymerization of ε-caprolactone, random copolymers were obtained. The formation of random copolymers was attributed to the occurrence of transesterification reactions. These side reactions were caused by the ε-caprolactone derived hydroxyl end groups generated during the copolymerization of ε-caprolactone with pre-polymers of L-lactide. The polymerization proceeds through an ester alcoholysis reaction mechanism, in which the stannous octoate activated ester groups of the monomers react with hydroxyl groups

Does your robot know? Enhancing children's information retrieval through spoken conversation with responsible robots

In this paper, we identify challenges in children's current information retrieval process, and propose conversational robots as an opportunity to ease this process in a responsible way. Tools children currently use in this process, such as search engines on a computer or voice agents, do not always meet their specific needs. The conversational robot we propose maintains context, asks clarifying questions, and gives suggestions in order to better meet children's needs. Since children are often too trusting of robots, we propose to have the robot measure, monitor and adapt to the trust the child has in the robot. This way, we hope to induce a critical attitude with the children during their information retrieval process.Comment: IR4Children'21 workshop at SIGIR 2021 - http://www.fab4.science/IR4C

Enhancing offshore service vessel concept design by involving seakeeping: developing a framework to efficiently design high performance offshore service vessel concepts

Algorithms and the Foundations of Software technolog

Computer aided synthesis: a game theoretic approach

In this invited contribution, we propose a comprehensive introduction to game theory applied in computer aided synthesis. In this context, we give some classical results on two-player zero-sum games and then on multi-player non zero-sum games. The simple case of one-player games is strongly related to automata theory on infinite words. All along the article, we focus on general approaches to solve the studied problems, and we provide several illustrative examples as well as intuitions on the proofs.Comment: Invitation contribution for conference "Developments in Language Theory" (DLT 2017

Structural Response of Bow Structures with Sonar Domes

Naval vessels are designed to remain operational in severe conditions, sea-state 6 or higher, and have to maintain a minimum forward speed in these conditions. These seakeeping conditions may result in severe impact loads on the bow of the vessel, called slamming. Sonar domes are often used at naval vessels to detect objects under water and are located at the forefoot of the vessel. The sonar dome used by the Royal Netherlands Navy is a composite structure connected under the steel bow structure of the vessel and is filled with water. Slamming and other seakeeping loads at the composite sonar dome have to be transferred to the steel bow structure through the composite and water inside the dome. Slamming loads have an impact type of character, which is described as a sudden quick increase of the load and with a short duration. Previous research has shown that neglecting the loads at the dome structure results in a serious underprediction of local structural response of the bow of the vessel. Besides that, little is known about the load transfer from the dome towards the bow structure. First, the dynamic response of a fluid filled composite sonar dome is studied. Different load types are applied at the sonar dome model to study the influence of the internal fluid on the response. Second, the effect of the loading transferred from the sonar dome on the stress levels in steel bow structure is studied. Slamming loads at the dome structure do not result in a highly dynamic response for the considered design. The rise-times of the loads have a relative long duration compared to the lowest natural response period of the sonar dome. The rise-times observed in the studied seakeeping conditions is in general much longer compared to the natural response periods of the dome. Including the internal fluid in the dome results in a reduction of the deformation and stresses of the composite shell. During seakeeping loading the pressure in the internal fluid rises, resulting in a pressure load on the bow structure above the dome. The reduction of internal pressure due to the outflow of water from the dome to an expansion container seems to be rather limited The presence of a sonar dome results in additional loads at the bow structure. These loads are a force at the dome flange and a pressure load on the bow structure above the dome. This leads to an increased stress level of the structural elements directly above the dome. It is concluded that the contribution of the internal pressure within the dome to the stress levels of the bow structure is most relevant. Vessels without a sonar dome do not have a deck in the forefoot of the vessel that is loaded by a fluid pressure. It is concluded that the loads from the sonar dome should not be neglected in a structural analysis of the bow structure.Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyScience Ship & Offshore Stucture

Huddersfield Open Access Publishing (HOAP) Project

The JISC funded Huddersfield Open Access Publishing (HOAP) Project aimed to develop a low cost sustainable Open Access (OA) journal publishing platform using EPrints Institutional Repository software. This poster will report on the development of the HOAP platform and discuss the outcomes of the project. The platform was developed to convert the peer reviewed, Teaching in Lifelong Learning journal, from its existing print subscription model to an OA e-journal. A specific front end was created for the journal, with content being archived in the University Repository. As part of this work, there has been a re-write of the notes for contributors section and a move from copyright transfer to a licence to publish model. HOAP is now a member of CrossRef and the Committee on Publishing Ethics, the journal has also been submitted to the Directory of Open Access Journals. The platform will also be used to launch a new title, Huddersfield Research Review during 2012. This title will showcase the most significant research at the University of Huddersfield by including interviews with the authors of the most cited and/or downloaded articles in the Repository together with an editorial overview by a senior researcher who will locate Huddersfield research within the broader national and international literature in the relevant fields and disciplines. An audit of the University’s journals resulted in the addition of another title during the project and also the potential for five others to be hosted, including two new peer-reviewed OA titles in 2012. In order to disseminate its output, the project developed a toolkit for other institutions, including new workflows, a licence to publish template and guidelines for new title proposals. The project hopes the toolkit will inspire other institutions to investigate OA journal publishing. A major output of HOAP for Huddersfield has been a fundamental change in the understanding of the utility of Institutional Repositories in which ‘innovation’ and ‘impact’ displace ‘management’ and ‘preservation” as the primary functions. The HOAP platform provides not only an interface through which both original and archived peer-reviewed content can be delivered in a sustainable OA format but also a means of delivering specialist content to specific academic audiences through a traditional journal front-end. The poster will share the recommendations for further developments at Huddersfield and implications for the wider community