161 research outputs found
A Deterministic Memory Allocator for Dynamic Symbolic Execution (Artifact)
No full textKDAlloc is a deterministic memory allocator for Dynamic Symbolic Execution. This artifact provides the allocator itself, integrated into the KLEE symbolic execution engine and the evaluation thereof
A deterministic memory allocator for dynamic symbolic execution
No full textDynamic symbolic execution (DSE) has established itself as an effective testing and analysis technique. While the memory model in DSE has attracted significant attention, the memory allocator has been
largely ignored, despite its significant influence on DSE.
In this paper, we discuss the different ways in which the memory allocator can influence DSE and the main design principles that a memory allocator for DSE needs to follow: support for external calls, cross-run and cross-path determinism, spatially and temporally distanced allocations, and stability. We then present KDAlloc, a deterministic allocator for DSE that is guided by these six design principles.
We implement KDAlloc in KLEE, a popular DSE engine, and first show that it is competitive with KLEE’s default allocator in terms of performance and memory overhead, and in fact significantly improves performance in several cases. We then highlight its benefits for use-after-free error detection and two distinct DSE-based techniques: MoKlee, a system for saving DSE runs to disk and later (partially) restoring them, and SymLive, a system for finding infinite-loop bugs
On detection thresholds–a review on diagnostic approaches in the infectious disease laboratory and the interpretation of their results
No full textReplication and transmission of porcine circovirus type 2 in mice
No full textLittle information is known about infection, replication and transmission of porcine circovirus type 2 (PCV2) in species other than swine. Two sets of animal experiments were carried out to investigate the susceptibility of mice to PCV2 and to study their possible role in maintaining and transmitting the virus. In the first experiment 14 mice were inoculated with PCV2 by the intraperitoneal route with 5 × 102 TCID 50 of the PCV2-ROM strain (Cadar et al., 2007). In a second experiment 24 mice were divided into two groups (A and B); mice in Group A (n = 18) were inoculated orally with 1 × 105 TCID 50
PCV2-ROM and mice in Group B (n = 6) were left uninoculated until day 12 post inoculation (p.i.), when they were mixed with Group A. The animals were sacrificed at intervals for postmortem investigation and virus genome detection by polymerase chain reaction (PCR). The PCR results indicated that PCV2 could replicate in mice infected intraperitoneally or by the oral route, and that the virus can be transmitted directly from mouse to mouse
Nalanda: a socio-technical graph platform for building software analytics tools at enterprise scale
No full textSoftware development is information-dense knowledge work that requires collaboration with other developers and awareness of artifacts such as work items, pull requests, and file changes. With the speed of development increasing, information overload and information discovery are challenges for people developing and maintaining these systems. Finding information about similar code changes and experts is difficult for software engineers, especially when they work in large software systems or have just recently joined a project. In this paper, we build a large scale data platform named Nalanda platform to address the challenges of information overload and discovery. Nalanda contains two subsystems: (1) a large scale socio-technical graph system, named Nalanda graph system, and (2) a large scale index system, named Nalanda index system that aims at satisfying the information needs of software developers. To show the versatility of the Nalanda platform, we built two applications: (1) a software analytics application with a news feed named MyNalanda that has Daily Active Users (DAU) of 290 and Monthly Active Users (MAU) of 590, and (2) a recommendation system for related work items and pull requests that accomplished similar tasks (artifact recommendation) and a recommendation system for subject matter experts (expert recommendation), augmented by the Nalanda socio-technical graph. Initial studies of the two applications found that developers and engineering managers are favorable toward continued use of the news feed application for information discovery. The studies also found that developers agreed that a system like Nalanda artifact and expert recommendation application could reduce the time spent and the number of places needed to visit to find information. Software Technolog
Symbolic execution of verification languages and floating-point code
No full textThe focus of this thesis is a program analysis technique named symbolic
execution. We present three main contributions to this field.
First, an investigation into comparing several state-of-the-art program
analysis tools at the level of an intermediate verification language over a
large set of benchmarks, and improvements to the state-of-the-art of symbolic
execution for this language. This is explored via a new tool, Symbooglix, that
operates on the Boogie intermediate verification language.
Second, an investigation into performing symbolic execution of floating-point
programs via a standardised theory of floating-point arithmetic that is
supported by several existing constraint solvers. This is investigated via two
independent extensions of the KLEE symbolic execution engine to support
reasoning about floating-point operations (with one tool developed by the
thesis author).
Third, an investigation into the use of coverage-guided fuzzing as a means for
solving constraints over finite data types, inspired by the difficulties
associated with solving floating-point constraints. The associated prototype
tool, JFS, which builds on the LibFuzzer project, can at present be applied to
a wide range of SMT queries over bit-vector and floating-point variables, and
shows promise on floating-point constraints.Open Acces
ROMANIA: MANY ENTREPRENEURS BUT FEW INNOVATORS
No full textEntrepreneurship is considered an essential element for the development and prosperity of contemporary economies. The already known traits: creating jobs, boosting growth, revenues to the state budget, are supplemented by vitality and adaptability, and not least, a capacity for innovation. Thus, innovation became one of the most important factors in the companies’ activity. However, innovation doesn’t only mean new products and services. It is closely related to the capacity of entrepreneurs and managers to apply new business models, embedding an organizational culture capable to identify how new ideas could be converted into value for business and society. Innovation supports the efforts of ambitious entrepreneurs to pursue their objectives and stimulate other potential entrepreneurs to enter into businesses. Innovation generates, directly and indirectly, positive effects not only within a company but also within the national economy, as a whole. Despite this empirical evidence, the link between entrepreneurship and innovation is difficult to describe, to introduce it in strong theoretical models, in order to substantiate viable political programs. First, only a relatively small part of entrepreneurs really innovate. Secondly, researchers reveal deep, but subtle, ties between the entrepreneurs’ profile, availability for innovation and effects on states’ competitiveness and prosperity. Finally, the number (or proportion) of entrepreneurs isn’t the most relevant, but their availability to innovate, the type of innovation chosen and, especially, how entrepreneurial organizations stimulate innovative initiatives among their employees (intrapreneurship). From this point of view, Romania's situation is difficult and challenging. The importance and size of the sector, entrepreneurial motivations, or the share of early stage innovative entrepreneurs indicate an average position at a global or European Union (EU) level. However, Romania is a modest innovator, often ranked last in the EU for a several innovation indicators, and its innovation performance in 2014 is at a significantly lower level compared to 2007. The poorest relative performance has been registered for the Linkages & entrepreneurship indicator. Our research also performs a comparison between entrepreneurship and innovation indicators, for Romania and selected Central and Eastern European states, to better understand the gap regarding a reasonable performance in innovation
Neural Termination Analysis
No full textWe introduce a novel approach to the automated termination analysis of
computer programs: we use neural networks to represent ranking functions.
Ranking functions map program states to values that are bounded from below and
decrease as a program runs; the existence of a ranking function proves that the
program terminates. We train a neural network from sampled execution traces of
a program so that the network's output decreases along the traces; then, we use
symbolic reasoning to formally verify that it generalises to all possible
executions. Upon the affirmative answer we obtain a formal certificate of
termination for the program, which we call a neural ranking function. We
demonstrate that thanks to the ability of neural networks to represent
nonlinear functions our method succeeds over programs that are beyond the reach
of state-of-the-art tools. This includes programs that use disjunctions in
their loop conditions and programs that include nonlinear expressions.Comment: To appear in the proceedings of ESEC/FSE '2
Innovation and performance. An analysis on European and Romanian companies
No full textThe challenges of the economy and of the modern society based on knowledge are closely related to the success of firms, their ability to generate new, innovative products and services, in a steady pace and in a large, diverse structure in order to ensure performance and long-term welfare. In a global world where countries compete to produce and promote the market for quality and convenient products for the consumers, the innovation capacity of a country and the innovative capabilities of companies acquire a special importance. Numerous studies have analyzed the determinants of innovation of the innovative activities in companies, focusing in particular on organizational and technological capabilities and associated strategies required for successful innovation. There are different types of measuring innovation at the firm level, and in this paper we chose four main groups inspired by the typology promoted by OECD and Eurostat: product innovation, process innovation, organizational innovation, marketing innovation. To remain competitive in the long term, companies must consider all these areas, introduce new products to market, improve the quality of the existing products, upgrade or purchase new production technologies. Based on statistical reports of world and national organizations, our research highlights an extremely diverse and heterogeneous picture of the performance innovation indicators in Europe and the situation in Romania, by comparison both with the EU average, with countries in Central and Eastern Europe (CEE), but also with their own performance in prior periods
Entrepreneur, Entrepreneurship and Intrapreneurship. A Literature Review
No full textEntrepreneurship is nowadays a buzz word, present both in political arguments and discussions, in official debates and also in the economic literature. However, the entrepreneurship and the recognition of the entrepreneur’s role for the economic system have been revealed by different authors for two centuries. Despite of this fact, there are
still controversies regarding the meaning and significance of the entrepreneur and entrepreneurship. Since then, and especially in the latest decades, some new concepts have been added to the already rich literature, e.g. intrapreneur and intrapreneurship. This paper is a modest attempt to review some old but also some recent approaches concerning the named terms and concepts, and thud contributing to a better understanding and use of these concepts. After reminding some relevant approaches regarding the terms
entrepreneur and entrepreneurship, the newly emerged terms have been in our attention.
Indeed, while notions like „entrepreneur” and „entrepreneurship” are widely used and known, the words „intrapreneur” and „intrapreneurship” are less commonly used and much more new but in rapidly spreading, due to the fact that the recent decades have been labeled by certain economists as „the entrepreneurship era”. The reason why the notion of intrapreneurship is less known than that of entrepreneurship is very simple to explain: the former one is pretty new, whereas the latter one has a history of over 200 years
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