Declarative Aspect Composition

Aspect-oriented languages provide means to attach certain program units (e.g. advice, filters) to a given set of join points. It is possible that not just a single , but several units need to execute at the same join point. Aspects that specify the insertion of these units are said to "share" the same join point. Such shared join points may give rise to several issues, such as determining the exact execution order and the dependencies among the aspects. In this position paper, we outline a declarative approach that addresses this problem. We evaluate it with respect to several software engineering properties, in particular comprehensibility, predictability and evolvability

Rethinking benchmark dates in international relations

International Relations has an ‘orthodox set’ of benchmark dates by which much of its research and teaching is organized: 1500, 1648, 1919, 1945 and 1989. This article argues that International Relations scholars need to question the ways in which these orthodox dates serve as internal and external points of reference, think more critically about how benchmark dates are established, and generate a revised set of benchmark dates that better reflects macro-historical international dynamics. The first part of the article questions the appropriateness of the orthodox set of benchmark dates as ways of framing the discipline’s self-understanding. The second and third sections look at what counts as a benchmark date, and why. We systematize benchmark dates drawn from mainstream International Relations theories (realism, liberalism, constructivism/English School and sociological approaches) and then aggregate their criteria. The fourth section of the article uses this exercise to construct a revised set of benchmark dates which can widen the discipline’s theoretical and historical scope. We outline a way of ranking benchmark dates and suggest a means of assessing recent candidates for benchmark status. Overall, the article delivers two main benefits: first, an improved heuristic by which to think critically about foundational dates in the discipline; and, second, a revised set of benchmark dates which can help shift International Relations’ centre of gravity away from dynamics of war and peace, and towards a broader range of macro-historical dynamics

Guarding art galleries by guarding witnesses

Let P be a simple polygon. We de ne a witness set W to be a set of points su h that if any (prospective) guard set G guards W, then it is guaranteed that G guards P . We show that not all polygons admit a nite witness set. If a fi nite minimal witness set exists, then it cannot contain any witness in the interior of P ; all witnesses must lie on the boundary of P , and there an be at most one witness in the interior of any edge. We give an algorithm to compute a minimal witness set for P in O(n2 log n) time, if such a set exists, or to report the non-existence within the same time bounds. We also outline an algorithm that uses a witness set for P to test whether a (prospective) guard set sees all points in P