Towards correct-by-construction product variants of a software product line: GFML, a formal language for feature modules

Software Product Line Engineering (SPLE) is a software engineering paradigm that focuses on reuse and variability. Although feature-oriented programming (FOP) can implement software product line efficiently, we still need a method to generate and prove correctness of all product variants more efficiently and automatically. In this context, we propose to manipulate feature modules which contain three kinds of artifacts: specification, code and correctness proof. We depict a methodology and a platform that help the user to automatically produce correct-by-construction product variants from the related feature modules. As a first step of this project, we begin by proposing a language, GFML, allowing the developer to write such feature modules. This language is designed so that the artifacts can be easily reused and composed. GFML files contain the different artifacts mentioned above.The idea is to compile them into FoCaLiZe, a language for specification, implementation and formal proof with some object-oriented flavor. In this paper, we define and illustrate this language. We also introduce a way to compose the feature modules on some examples.Comment: In Proceedings FMSPLE 2015, arXiv:1504.0301

A Rule-driven Approach for Defining the Behavior of Negotiating Software Agents

One problem with existing agent-mediated negotiation systems is that they rely on ad hoc, static, non-adaptive, and hardcoded schemes to represent the behaviour of agents. This limitation is probably due to the complexity of the negotiation task itself. Indeed, while negotiating, software (human) agents face tough decisions. These decisions are based not only on the information made available by the negotiation server, but on the behaviour of the other participants in the negotiation process as well. The information and the behaviour in question are constantly changing and highly uncertain. In the first part of the paper, we propose a rule-driven approach to represent, manage and explore negotiation strategies and coordination information. For that, we divide the behaviour of negotiating agents into protocols, strategies and coordination. Among the many advantages of the proposed solution, we can cite the high level of abstraction, the closeness to human understanding, the versatility, and the possibility to modify the agents' behaviour during the negotiation process. To validate our solution, we ran many agent tournaments, and used the rule-driven approach to implement bidding strategies that are common in the English and Dutch auctions. We also implemented simple coordination schemes across several auctions. The ongoing validation work is detailed and discussed in the second part of the paper. Un des inconvénients qu'on retrouve fréquemment dans les systèmes de négociation par agents est qu'ils reposent sur des schémas ad-hoc, non adaptatifs et figés dans le code pour représenter le comportement des agents. Cette limitation est probablement due à la complexité de l'activité de négociation elle-même. En effet, au cours de la négociation, les agents logiciels (humains) ont des décisions difficiles à prendre. Ces décisions ne sont pas seulement basées sur l'information disponible sur le serveur de négociation, mais aussi sur le comportement des autres participants durant le processus de négociation. L'information et le comportement en question changent constamment et sont très incertains. Dans la première partie de l'article, nous proposons une approche à base de règles pour représenter, gérer et explorer les stratégies de négociation ainsi que l'information de coordination. Parmi les nombreux avantages de la solution proposée, on peut citer le haut niveau d'abstraction, la proximité avec la compréhension humaine, la souplesse d'utilisation et la possibilité de modifier le comportement des agents durant le processus de négociation. Pour valider notre solution, nous avons effectué plusieurs tournois entre agents et utilisé l'approche à base de règles pour implémenter des stratégies simples applicables à l'enchère anglaise et à l'enchère hollandaise. Nous avons aussi implémenté des schémas simples de coordination impliquant plusieurs enchères. Le travail de validation, en cours, est détaillé et discuté dans la seconde partie de l'article.e-negotiation, online auction, software agent, negotiation strategy, coordination, rule-based system, rule engine, Négociation électronique, enchères en ligne, agents logiciels, stratégie de négociation, coordination, système à base de règles, moteur de règles

A prognosis oriented microscopic stock market model

We present a new microscopic stochastic model for an ensemble of interacting investors that buy and sell stocks in discrete time steps via limit orders based on individual forecasts about the price of the stock. These orders determine the supply and demand fixing after each round (time step) the new price of the stock according to which the limited buy and sell orders are then executed and new forecasts are made. We show via numerical simulation of this model that the distribution of price differences obeys an exponentially truncated Levy-distribution with a self similarity exponent mu~5.Comment: 14 pages RevTeX, 5 eps-figures include

Technical and marketing support systems for successful small and medium-size enterprises in four countries

Studies of successful and medium-size enterprises (SMEs) and their marketing and technical support systems were undertaken for Colombia, Indonesia, Japan, and the Republic of Korea. Three to four subsectors were examined in each country. The sample worldwide amounted to 445 firms. Mechanisms to support export marketing varied across countries and subsectors. How they varied depended greatly on whether SMEs operated within well-developed private networks. When market penetration begins, transaction costs are high and collective marketing support can be important. As markets"thicken,"initiatives by foreign buyers become more important. Generally the most effective collective marketing support was of the kind that can be provided more effectively by decentralized organizations - such as industry associations or local governments and chambers of commerce (support firms'participation in trade fairs, for example) - than by central government institutions. Private mechanisms were more important than collective mechanisms for helping firms improve their technological capability. Demand for collective mechanisms tended to be greater when technological requirements of production were complex or when the endowments of private technological networks in certain countries or industries were weak. Broad-based collective technical support facilitates the emergence of an information-rich environment for firms, and may be worth pursuing in many settings. Examples of such support include: 1) sponsoring courses in specialized topics; 2) facilitating the use of expert consultants (either directly, by making a consultant available to a broad array of firms, or indirectly, by providing financial support for the use of consultants); and 3) promoting information-sharing among firms. Countries that already have strong broad-based collective support and that are moving into technologically more advanced activities might consider"high-intensity"support, but should proceed with caution.Microfinance,Small and Medium Size Enterprises,Small Scale Enterprise,Markets and Market Access,Water Conservation,Microfinance,Private Participation in Infrastructure,Small Scale Enterprise,Access to Markets,Markets and Market Access

Context effects in diverse-category brand environments: The influence of target product positioning and consumers' processing mind-set

We investigate the apparent rarity of contrast effects in diverse-category contextual and target product settings. Three studies show that the direction of context effects depends on (a) whether target product positioning is abstract or concrete, (b) consumers’ adoption of an item-specific, similarity-focused relational or dissimilarityfocused relational processing mind-set, and (c) the magnitude of resources allocated to processing. We find that contrast effects emerge when an ambiguous target product is positioned concretely, not abstractly, and consumers employ relational, not item-specific, processing. A framework clarifies how and when each of the aforementioned factors shapes context effects, often in ways never before seen. Whether in supermarkets teeming with assorted foods and home products, during commercial breaks filled with pools of ads, or in stadiums plastered with the signage of numerous sponsors, consumers frequently evaluate target products in contexts inhabited by goods from many different product categories. Not only do these categories typically differ from each other, but they also often differ from that of the target product. To exemplify, consider a trip to an upscale store where you might browse branded products from diverse categories, say, a Sony TV, Godiva candy, a Rolex watch, Aveda shampoo, and so on. Suppose that you then encountered a promotional appeal for an unknown vacation resort. Would your evaluation of the ambiguous target resort differ if the earlier-examined multicategory products *Kyeongheui Kim is assistant professor of marketing, at the Departmen

Self-organization of value and demand

We study the dynamics of exchange value in a system composed of many interacting agents. The simple model we propose exhibits cooperative emergence and collapse of global value for individual goods. We demonstrate that the demand that drives the value exhibits non Gaussian "fat tails" and typical fluctuations which grow with time interval with a Hurst exponent of 0.7.Comment: RevTex, 4 pages, 3 figure

Optimal pricing strategies for capacity leasing based on time and volume usage in telecommunication networks

In this study, we use a monopoly pricing model to examine the optimal pricing strategies for “pay-per-time”, “pay-per-volume” and “pay-per both time and volume” based leasing of data networks. Traditionally, network capacity distribution includes short/long term bandwidth and/or usage time leasing. Each consumer has a choice to select volume based, connection-time based or both volume and connection-time based pricing. When customers choose connection-time based pricing, their optimal behavior would be utilizing the bandwidth capacity fully, which can cause network to burst. Also, offering the pay-per-volume scheme to the consumer provides the advantage of leasing the excess capacity to other potential customers serving as network providers. However, volume-based strategies are decreasing the consumers’ interest and usage, because the optimal behaviors of the customers who choose the pay-per-volume pricing scheme generally encourages them to send only enough bytes for time-fixed tasks (for real time applications), causing quality of the task to decrease, which in turn creating an opportunity cost. Choosing pay-per time and volume hybridized pricing scheme allows customers to take advantages of both pricing strategies while decreasing (minimizing) the disadvantages of each, because consumers generally have both time-fixed and size-fixed task such as batch data transactions. However, such a complex pricing policy may confuse and frighten consumers. Therefore, in this study we examined the following two issues: (i) what (if any) are the benefits to the network provider of providing the time and volume hybridized pricing scheme? and (ii) would this offering schema make an impact on the market size? The main contribution of this study is to show that pay-per both time and volume pricing is a viable and often preferable alternative to the only time and/or only volume-based offerings for a large number of customers, and that judicious use of such pricing policy is profitable to the network provider

Application of Zhangs Square Root Law and Herding to Financial Markets

We apply an asymmetric version of Kirman's herding model to volatile financial markets. In the relation between returns and agent concentration we use the square root law proposed by Zhang. This can be derived by extending the idea of a critical mean field theory suggested by Plerou et al. We show that this model is equivalent to the so called 3/2-model of stochastic volatility. The description of the unconditional distribution for the absolute returns is in good agreement with the DAX independent whether one uses the square root or a conventional linear relation. Only the statistic of extreme events prefers the former. The description of the autocorrelations are in much better agreement for the square root law. The volatility clusters are described by a scaling law for the distribution of returns conditional to the value at the previous day in good agreement with the data.Comment: 25 pages, 3 figures, Late