αRby—An Embedding of Alloy in Ruby

We present αRby—an embedding of the Alloy language in Ruby—and demonstrate the benefits of having a declarative modeling language (backed by an automated solver) embedded in a traditional object-oriented imperative programming language. This approach aims to bring these two distinct paradigms (imperative and declarative) together in a novel way. We argue that having the other paradigm available within the same language is beneficial to both the modeling community of Alloy users and the object-oriented community of Ruby programmers. In this paper, we primarily focus on the benefits for the Alloy community, namely, how αRby provides elegant solutions to several well-known, outstanding problems: (1) mixed execution, (2) specifying partial instances, (3) staged model finding

Executable specifications for Java programs

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 55-57).In this thesis, we present a unified environment for running declarative specifications in the context of an imperative object-oriented programming language. Specifications are Alloy-like, written in first-order relational logic with transitive closure, and the imperative language for this purpose is Java. By being able to mix imperative code with executable declarative specifications, the user can easily express constraint problems in-place, i.e. in terms of the existing data structures and objects on the heap. After a solution is found, our framework will automatically update the heap to reflect the solution, so the user can continue to manipulate the program heap in the usual imperative way, without ever having to manually translate the problem back and forth between the host programming environment and the solver language. We show that this approach is not only convenient, but, for certain problems, like puzzles or NP-complete graph algorithms, it can also outperform the manual implementation. We also present an optimization technique that allowed us to run our tool on heaps with almost 2000 objects.by Aleksandar Milicevic.S.M

Model-based, event-driven programming paradigm for interactive web applications

Applications are increasingly distributed and event-driven. Advances in web frameworks have made it easier to program standalone servers and their clients, but these applications remain hard to write. A model-based programming paradigm is proposed that allows a programmer to represent a distributed application as if it were a simple sequential program, with atomic actions updating a single, shared global state. A runtime environment executes the program on a collection of clients and servers, automatically handling (and hiding from the programmer) complications such as network communication (including server push), serialization, concurrency and races, persistent storage of data, and queuing and coordination of events.National Science Foundation (U.S.) (Grant CCF-1138967)National Science Foundation (U.S.) (Grant CCF-1012759)National Science Foundation (U.S.) (Grant CCF-0746856

Shelf Based Out-of-Stocks in the Context of Employee Density

The purpose of this paper is to investigate the effect of employee density on shelf based out-of-stocks, i.e. situations when products are physically present at stores, but not on the marked sale positions. In addition, for the first time, these relations were analyzed among different retail formats. By using POS estimation method, shelf based out-of-stock rates were measured for 80 different FMCG products in 97 retail stores. For analyzing the impact of employee density on the average shelf based OOS rate in modern and traditional retail formats, curvilinear hierarchical regression and moderation analyses were used. The results showed that the relation between employee density and shelf based out-of-sock varied among different formats. While it was not significant in convenience stores, in modern formats it was quadratic (stores with too many or too few employees per square meter were related to higher levels of shelf based OOS). The obtained results suggest that store managers should be aware of the effects of employee organization on product availability. The attention was also dedicated to potential problems and managerial implications concerning the employees' number in retail stores, regarding traditional and modern trading formats

Unifying Execution of Imperative and Declarative Code

We present a unified environment for running declarative specifications in the context of an imperative object-Oriented programming language. Specifications are Alloy-like, written in first-order relational logic with transitive closure, and the imperative language is Java. By being able to mix imperative code with executable declarative specifications, the user can easily express constraint problems in place, i.e., in terms of the existing data structures and objects on the heap. After a solution is found, the heap is updated to reflect the solution, so the user can continue to manipulate the program heap in the usual imperative way. We show that this approach is not only convenient, but, for certain problems can also outperform a standard imperative implementation. We also present an optimization technique that allowed us to run our tool on heaps with almost 2000 objects

A lightweight code analysis and its role in evaluation of a dependability case

A dependability case is an explicit, end-to-end argument, based on concrete evidence, that a system satisfies a critical property. We report on a case study constructing a dependability case for the control software of a medical device. The key novelty of our approach is a lightweight code analysis that generates a list of side conditions that correspond to assumptions to be discharged about the code and the environment in which it executes. This represents an unconventional trade-off between, at one extreme, more ambitious analyses that attempt to discharge all conditions automatically (but which cannot even in principle handle environmental assumptions), and at the other, flow- or context-insensitive analyses that require more user involvement. The results of the analysis suggested a variety of ways in which the dependability of the system might be improved.National Science Foundation (U.S.). (Deep and Scalable Analysis of Software) (Grant number 0541183)National Science Foundation (U.S.). Division of Computer and Network Systems (CRI: CRD – Development of Alloy Tools, Technology and Materials) (Grant number 0707612

Alloy*: A Higher-Order Relational Constraint Solver

The last decade has seen a dramatic growth in the use of constraint solvers as a computational mechanism, not only for analysis and synthesis of software, but also at runtime. Solvers are available for a variety of logics but are generally restricted to first-order formulas. Some tasks, however, most notably those involving synthesis, are inherently higher order; these are typically handled by embedding a first-order solver (such as a SAT or SMT solver) in a domain-specific algorithm. Using strategies similar to those used in such algorithms, we show how to extend a first-order solver (in this case Kodkod, a model finder for relational logic used as the engine of the Alloy Analyzer) so that it can handle quantifications over higher-order structures. The resulting solver is sufficiently general that it can be applied to a range of problems; it is higher order, so that it can be applied directly, without embedding in another algorithm; and it performs well enough to be competitive with specialized tools on standard benchmarks. Although the approach is demonstrated for a particular relational logic, the principles behind it could be applied to other first-order solvers. Just as the identification of first-order solvers as reusable backends advanced the performance of specialized tools and simplified their architecture, factoring out higher-ordersolvers may bring similar benefits to a new class of tools

New Market Segmentation Knowledge in the Function of Bioeconomy Development in Serbia

Sustainability of companies in modern market conditions greately depends on the knowledge. In order to improve their business processes and satisfy the needs of their customers, managers have to rely on new marketing knowledge, especially in new sectors such as bioeconomy. The aim of this paper is to investigate potential added value to Serbian organic food market segmentation researches (belonging to preconditions of further bioeconomy development) when implementing new marketing knowledge – food-related lifestyle market segmentation and scales’ testings. The results point out to adventurous consumers as the most important current and future market for organic food. Besides being the most educated (what was already established for consumers accepting organic food well in previous domestic researches), it is the first time that consumers accepting organic food in larger extent are brought in connection to their inclusion of the whole family in the preparation of meals and acceptance of novelties in cooking. It is also the first time to identify that there is a segment in domestic conditions for which price is not the greatest obstacle for increasing organic food consumption. That can be of the great importance for all actors (both national and foreign) operating at domestic food market

Primary spinal glioblastoma multiforme. Single center experience and literature review

Abstract Objectives Spinal glioblastomas represent a rare entity accounting for ca 1–3% of all intramedullary tumors; data about survival, prognostic factors and therapeutic protocols are quite poor. Even with an aggressive multimodal management the spinal glioblastoma patients' survival remains poor, with rapid progression of the disease. This study reports our experience with the management of the primary intramedullary glioblastomas, also in regard to the current literature data. Patients and Methods We retrospectively analyzed the medical records of 5 patients treated at the Department for Neuro-oncology and Spine Surgery of the Clinical Center of Belgrade, Serbia, between January 2007 and December 2016 for a primary intramedullary glioblastoma. Demographic characteristics, pre-operative data and post-operative results were then compared with previous literature regarding spinal GBMs and attempt to identify potential prognostic factors. Results Gross total resection was achieved in two patients, while a subtotal resection was performed in the latter 3 cases; as per protocol, all patients underwent to surgery, followed by radio and chemotherapy. There were no intraoperative complications and no patients developed a new postoperative neurological defect; the median overall survival was 6 months. Progression or recurrence of disease was noted in all patients at the 3-months follow-up, despite the adjuvant treatments. Conclusions To the date, there is a lack of consensus on specific management of spinal glioblastomas: the extent of resection can play an important role, but it appears to be not preeminent. A shorter interval between symptoms onset and treatment and a smaller extension of the tumor seem to be correlated with better outcomes and a longer overall survival. However, there is not an adjunctive viable standardized postoperative therapy yet, which results in concrete and persistent improvement of overall survival and progression free survival

Integrisan proces proizvodnje abrazivnih reznih elemenata bagera u rudarskoj industriji

The paper presents an integrated production process for excavator cutting elements in the mining industry based on modern software systems for the optimization and management of casting process parameters through simulations. The concept involves the virtual manufacture, practical implementation of the established technological process and quality control of final castings i.e. excavator cutting elements. The presented production methodology reduces the time required to develop and manufacture the new product compared to the traditional methods of prototype testing.Publishe