Confluence Competition 2019

The Confluence Competition (CoCo)4 is an annual competition of software tools that aim to prove or disprove confluence and related (undecidable) properties of a variety of rewrite formalisms automatically. Initiated in 2012, CoCo runs live in a single slot at a conference or workshop and is executed on the crosscommunity competition platform StarExec [20]. For each category, 100 suitable problems are randomly selected from the online database of confluence problems (COPS). Participating tools must answer YES or NO within 60 seconds, followed by a justification that is understandable by a human expert; any other output signals that the tool could not determine the status of the problem. CoCo 2019 features new categories on commutation, infeasibility problems, and confluence of string rewrite systems. Confluence provides a general notion of determinism and has been conceived as one of the central properties of rewriting. A rewrite system R is a set of directed equations, so called rewrite rules, which induces a rewrite relation →R on terms. We provide a simple exampl

(Re)conceptualising physical activity participation as career

Physical activity is increasingly positioned as playing an important role in preventing and mitigating many of the decrements associated with biological ageing. As a result, public health messages encourage older people to remain active in later life. Despite this, physical activity participation rates among older adults are low. This may be in part related to the conventional approach to understanding physical activity participation as a product of motivation. We contend that this approach does not allow for a deeper exploration of the wider structural, historical and discursive contexts in which physical activity participation occurs. Therefore, we propose that physical activity can be reconceptualised as a career. Through a synthesis of findings from four studies exploring physical activity experiences in later life, we demonstrate that beginning and maintaining a physical activity career requires a disposition towards physical activity, the legitimation of physically active practices and dealing with contingencies. In addition, we demonstrate that maintaining a physical activity career requires investment and deliberation to adapt physical activity practices continually within an individual's own personal biography. As such, we conclude that current strategies to promote physical activity to older adults are unlikely to result in increased levels of participation. To promote physical activity to older adults an understanding of how structural, cultural and historical contexts influence participation is needed

Historical Enquiry as a Critical Method in Urban Riverscape Revisions: The Case of Belgrade's Confluence

This article aims to underline the necessity of including historical enquiry in reaching the complex goals of sustainable development of urban riverscapes. Its proposed method is a survey conducted through selection, interpretation and systematization of the relevant historical data that consider the Belgrade cityscape, and specifically, the New Belgrade public spaces at the river confluence. The theoretical framework, which relies on the concepts of 'landscape urbanism' and 'critical practice of landscape architecture', has affected the selection and interpretation of dense historical layers of modernization, formed in diverse socio-economic and political conditions. We have distinguished five historical strata that contribute significantly to comprehension of the present state. By looking at the traces of the formative period of Belgrade urban landscape, the moments of New Belgrade's inception, inerasable impacts of war, vigorous post WWII socialist transformation and, finally, the series of Danube riverscape revisions, we intend to depict the complexity of the modern city legacy and thus stress the interconnectedness of past and future endeavours. As a counterpoint to globalizing tendencies in re-designing city riverfronts, this work is conceived as a lateral contribution to a broader investigation that informs, supports and constitutes more ecologically viable practices

infChecker. A Tool for Checking Infeasibility

[EN] Given a Conditional Term Rewriting System (CTRS) R and terms s and t, we say that the reachability condition s ->* t is *feasible* if there is a substitution \sigma instantiating the variables in s and t such that the *reachability test* \sigma(s)->* \sigma(t) succeeds; otherwise, we call it *infeasible*. Checking infeasibility of such (sequences of) reachability conditions is important in the analysis of computational properties of CTRSs, like confluence or operational termination. Recently, a logic-based approach to prove and disprove infeasibility has been introduced. In this paper we present infChecker, a new tool for checking infeasibility which is based on such an approach.Partially supported by the EU (FEDER), and projects RTI2018-094403-B-C32, PROMETEO/2019/098, and SP20180225. Raul Gutierrez was also supported by INCIBE program Ayudas para la excelencia de los equipos de investigacion avanzada en ciberseguridad.Gutiérrez Gil, R.; Lucas Alba, S. (2019). infChecker. A Tool for Checking Infeasibility. Universidade de Brasilia. 38-42. http://hdl.handle.net/10251/181069S384

TOOLympics II: competitions on formal methods:A Special Issue for TOOLympics 2019

This is the second issue in the new “Competitions and Challenges” (CoCha) theme of the International Journal on Software Tools for Technology Transfer. The new theme was established to support competitions and challenges with an appropriate publication venue. The first issue presented the competition on software testing Test-Comp 2019, which was part of the TOOLympics 2019 event. In this second issue for TOOLympics, we present selected competition reports. The TOOLympics event took place as part of the 25-years celebration of the conference TACAS. The goal of the event was to provide an overview of competitions and challenges in the area of formal methods

New approaches for exploring signal crayfish invasion biology and ecological impacts in headwater streams

The global spread of invasive alien species has had severe ecological, social and economic implications, with freshwater systems proving particularly vulnerable to invasion. Freshwater crayfish are exceptionally successful invaders, and 90% of species introduced to Europe have become established in the wild. As ecosystem engineers, crayfish present a significant threat to aquatic ecosystems. However, methodological constraints have thus far limited our understanding of invasive crayfish ecology and environmental impacts. This project aims to better our understanding of the spatio-temporal ecological impact invasive crayfish have on native biota, using Bookill Gill Beck and Long Preston Beck in the Yorkshire Dales as a case study. A novel method was developed to produce quantitative data on crayfish populations along an invasion gradient from well-established sites to the invasion front, where native crayfish still persist. The method was rigorously tested to evaluate efficiency and optimal deployment time for both crayfish and benthic fish. Following proof-of-concept, the method was then used to explore the invasion ecology and ecological impacts of signal crayfish within the headwater system. Population demographics of signal crayfish were investigated along the invasion gradient over three subsequent field seasons (2018 - 2020), focussing on population density, size structure and biomass, including relationships with substrate composition. Subsequently, density- dependent impacts of signal crayfish on macroinvertebrate and fish communities were explored, comparing sites along the invasion gradient and temporal changes at individual sites over the three-year timeframe. Notable changes in macroinvertebrate community composition and severe declines of native fish were observed, with European bullhead the most affected fish species. The results of this research can be used to inform conservation and management decisions by greatly enhancing our understanding of the invasion biology and ecological impacts of invasive crayfish, whilst also offering a novel method to be used in quantitative population assessments in future research and monitoring