A minimalistic look at widening operators

We consider the problem of formalizing the familiar notion of widening in abstract interpretation in higher-order logic. It turns out that many axioms of widening (e.g. widening sequences are ascending) are not useful for proving correctness. After keeping only useful axioms, we give an equivalent characterization of widening as a lazily constructed well-founded tree. In type systems supporting dependent products and sums, this tree can be made to reflect the condition of correct termination of the widening sequence

Stratified Static Analysis Based on Variable Dependencies

In static analysis by abstract interpretation, one often uses widening operators in order to enforce convergence within finite time to an inductive invariant. Certain widening operators, including the classical one over finite polyhedra, exhibit an unintuitive behavior: analyzing the program over a subset of its variables may lead a more precise result than analyzing the original program! In this article, we present simple workarounds for such behavior

Efficient Generation of Correctness Certificates for the Abstract Domain of Polyhedra

Polyhedra form an established abstract domain for inferring runtime properties of programs using abstract interpretation. Computations on them need to be certified for the whole static analysis results to be trusted. In this work, we look at how far we can get down the road of a posteriori verification to lower the overhead of certification of the abstract domain of polyhedra. We demonstrate methods for making the cost of inclusion certificate generation negligible. From a performance point of view, our single-representation, constraints-based implementation compares with state-of-the-art implementations

A Certified Denotational Abstract Interpreter

International audienceAbstract Interpretation proposes advanced techniques for static analysis of programs that raise specific challenges for machine-checked soundness proofs. Most classical dataflow analysis techniques iterate operators on lattices without infinite ascending chains. In contrast, abstract interpreters are looking for fixpoints in infinite lattices where widening and narrowing are used for accelerating the convergence. Smart iteration strategies are crucial when using such accelerating operators because they directly impact the precision of the analysis diagnostic. In this paper, we show how we manage to program and prove correct in Coq an abstract interpreter that uses iteration strategies based on program syntax. A key component of the formalization is the introduction of an intermediate semantics based on a generic least-fixpoint operator on complete lattices and allows us to decompose the soundness proof in an elegant manner

Egyptian Theatre and its Impact on Society: History, Deterioration, And Path For Rehabilitaition

Egypt is one of the oldest civilizations in the world, yet the lifespan of its theatre is rather short. It was not until the late 19th century that Egyptians were introduced to the disciplined form of theatre. Although the history of theatre in Egypt is short-lived, it had witnessed vigorous changes that lead to its rise and fall only within a few decades. Namely, those vigorous changes were the byproduct of the social and political movements that the Egyptian society underwent in less than a century. The Egyptian Theatre not only got affected by those political changes but also induced an integral influence on the Egyptian socio-political landscape, especially from the 50s until the mid- 70s. It was during those years that the Egyptian Theatre witnessed a golden age transitioning to a rapid phase of deterioration. Therefore, it was critically important to conduct an in-depth study towards finding means for reviving a theatre movement in Egypt. This is not only for the sake of reviving theatre as an art form but most importantly for theatre’s potential in contributing to the development of a more stable, literate and civil society, especially after two revolutions (January 25, 2011, and June 30, 2013.

Dynamic task scheduling and binding for many-core systems through stream rewriting

This thesis proposes a novel model of computation, called stream rewriting, for the specification and implementation of highly concurrent applications. Basically, the active tasks of an application and their dependencies are encoded as a token stream, which is iteratively modified by a set of rewriting rules at runtime. In order to estimate the performance and scalability of stream rewriting, a large number of experiments have been evaluated on many-core systems and the task management has been implemented in software and hardware.In dieser Dissertation wurde Stream Rewriting als eine neue Methode entwickelt, um Anwendungen mit einer großen Anzahl von dynamischen Tasks zu beschreiben und effizient zur Laufzeit verwalten zu können. Dabei werden die aktiven Tasks in einem Datenstrom verpackt, der zur Laufzeit durch wiederholtes Suchen und Ersetzen umgeschrieben wird. Um die Performance und Skalierbarkeit zu bestimmen, wurde eine Vielzahl von Experimenten mit Many-Core-Systemen durchgeführt und die Verwaltung von Tasks über Stream Rewriting in Software und Hardware implementiert

Restaurant Cultivator : Concept of a Restaurant Operated Indoor Garden

This project began in November 2016 by approaching Plantui Oy about a possible subject of my thesis. I met with the company’s Chief Technology Manager and we discussed the potential subject of the project. It was agreed, that I would propose a subject of my own interest, taking into account a desire from the company to have the final conccept in English. I wanted to create something new and significant that would, at the same time, serve the best interests of Plantui Oy. I researched the topic by identifying the current and future trends from a strategic perspective. After reviewing hydroponic gardens and determining the competing manufacturers, I discovered the market being full of products for domestic use. Restaurants and other users with a need for larger capacity were almost completely ignored. Restaurants have always adapted to the current trends. The Endurance Crisis mentioned in the 2016 Finnish Sitra Megatrend listing does not make any exceptions, as the leading restaurants are constantly striving to act more responsibly and to educate by example. (www.sitra.fi) According to the world’s top chefs, the main factors affecting the restaurant world in 2017 are reducing waste and strengthening sustainable development. (www.edition.cnn.com) Based on my observations, I came up with a concept of a hydroponic garden for professional use. By modifying Plantui’s existing technology, I perceived a functional concept of a restaurant based indoor garden. The company’s Chief Technology Manager approved of my topic, as it was in accord with their ongoing product development and with their visions for the future.Projektini alkoi marraskuussa 2016 lähestymällä Plantui Oy:tä opinnäytetyön mahdollisuudesta. Tapasin Plantui Oy:n teknologiajohtajan, jonka kanssa keskustelimme mahdollisesta aiheesta ja sovimme, että ehdotan heille mielestäni sopivaa aihetta. Plantui Oy:n toivomuksena oli saada lopullinen konsepti englanninkielisenä. Tavoitteenani oli luoda jotakin uutta ja merkittävää, mikä palvelisi samalla myös Plantui Oy:n etua. Aloitin varsinaisen aiheen etsimisen kartoittamalla alan nykyisiä ja tulevia trendejä lähinnä strategisesta näkökulmasta. Tarkasteltuani erilaisia hydroponisia puutarhoja ja määrittäessäni kilpailevia valmistajia, huomasin markkinoilta löytyvän monipuolista tarjontaa kotikeittiöiden tarpeisiin. Yllätyin kuitenkin havaitessani, kuinka ravintolat ja muut suuremman kapasiteetin tekijät, kuten suurkeittiöt, oli jätetty lähes kaikkien yritysten tuotevalikoimissa kokonaan huomiotta. Ravintolat ovat aina mukautuneet ajan trendeihin ja omalta osaltaan myös luoneet niitä, eikä suomalaisessa Sitra 2016 -megatrendilistassa mainittu kestävyyskriisi näytä olevan poikkeus tässäkään suhteessa. (https://www.sitra.fi) Johtavat ravintolat pyrkivät jatkuvasti toimimaan vastuullisemmin ja ohjaamaan muita omalla esimerkillään. Vuoden 2017 ravintolamaailman trendejä ja vaikuttavia tekijöitä ovat maailman huippukokkien mukaan muun muassa kestävä kehitys sekä hävikin minimointi. (http://edition.cnn.com) Tekemieni havaintojen perusteella ehdotin Plantui Oy:lle opinnäytetyöni aiheeksi konseptia ravintolakäyttöisestä hydroponisesta puutarhasta. Muokkaamalla heidän jo olemassa olevaa teknologiaansa uuteen muotoon olisi mahdollista saavuttaa toimiva konsepti ravintolan sisätiloihin sijoitettavasta puutarhasta. Plantui Oy:n teknologiajohtaja hyväksyi esittämäni aiheen, sillä se oli linjassa yrityksen omien tulevaisuudensuunnitelmien ja käynnissä olevan tuotekehityksen kanssa

Why use or?

Or constructions introduce a set of alternatives into the discourse. But alternativity does not exhaust speakers' intended messages. Speakers use the profiled or alternatives as a starting point for expressing a variety of readings. Ever since (Grice, H. Paul. 1989. Studies in the way of words. Cambridge, MA: Harvard University Press) and (Horn. 1972. On the semantic properties of the logical operators in English. Los Angeles, CA: University of California Los Angeles dissertation), the standard approach has assumed that or has an inclusive lexical meaning and a predominantly exclusive use, thus focusing on two readings. While another, "free choice", reading has been added to the repertoire, accounting for the exclusive reading remains a goal all or theorists must meet. We here propose that both "inclusive" and "exclusive" interpretations, as currently defined, do not capture speakers' intended readings, which we equate with the relevance-theoretic explicature. Adopting a usage-based approach to language, we examined all the or occurrences in the Santa Barbara Corpus of spoken American English (1053 tokens), and found that speakers use or utterances for a far richer variety of readings than has been recognized. In line with Cognitive Linguistics, we propose that speakers' communicated intentions are better analyzed in terms of subjective construals, rather than the objective conditions obtaining when the or proposition is true. We argue that in two of these readings speakers are not necessarily committed to even one of the alternatives being the case. In the most frequent reading, the overt disjuncts only serve as pointers to a higher-level concept, and it is that concept that the speaker intends to refer to

Meaning(s) in “Sustainable Tourism”: A Social Semiotic Approach

It can be argued that ”sustainable tourism” is considered to be a solution for ensuring the industry’s long-term survival. However, the concept of “sustainable tourism” is contested. A key issue is a lack of consensus in how stakeholders define “sustainable tourism”, and this creates communication challenges when different stakeholders discuss the concept. Within the field of sustainable tourism, there is limited literature on the meanings that stakeholder groups attribute to the concept of “sustainable tourism”. This study aims to address this theoretical gap, by exploring the meanings that stakeholders attribute to “sustainable tourism”, and the potential for the creation of shared meanings. This thesis addresses this gap by applying a social semiotic approach to exploring the meanings attributed to “sustainable tourism” by various stakeholder groups. Social semiotics is a theory that studies meanings created in groups, and is applied in this thesis as an analysis of “sustainable tourism” stakeholders’ web-pages. A total of 18 webpages from five stakeholder groups: the Public sector, the Tourism industry, Universities and research centres, the Third sector and Environmental and tourism consultancies, have been analysed for the purpose of this study. The findings of the thesis add value to both theory and practice. The theoretical contribution is twofold. Conceptually, the study has contributed to the theory of “sustainable tourism” by establishing that there is no orderliness in the ways that stakeholders conceptualise “sustainable tourism” meanings. Instead, further fragmentation of values, according to clusters or individual organisations within stakeholder groups, occurs. The meanings identified in this study can be organised into five dualities and tensions, and represent the positions in power relations in “sustainable tourism”. Methodologically, the study has contributed to the body of knowledge by introducing social semiotics into “sustainable tourism” research methodology, and by developing an original and replicable research instrument based on methods of social semiotics. The practical implications of the thesis are twofold as well. The meanings identified in the study can help breach perceptual gap between organisations in different stakeholder groups and clusters, promoting more effective communication, inclusion and participation in “sustainable tourism”. Furthermore, the original research instrument developed for this study can be adopted by practitioners for the analysis of their own webpage for the meanings conveyed