6,115 research outputs found
The delay and window size problems in rule-based stream reasoning
No full textIn recent years, there has been an increasing interest in extending stream processing engines with rule-based temporal reasoning capabilities. To ensure correctness, such systems must be able to output results over the partial data received so far as if the entire (infinite) stream had been available; furthermore, these results must be streamed out as soon as the relevant data is received, thus incurring the minimum possible delay; finally, due to memory limitations, systems can only keep a limited history of previous facts in memory to perform further computations. These requirements pose significant theoretical and practical challenges since temporal rules can derive new information and propagate it both towards past and future time points; as a result, streamed answers can depend on data that has not yet been received, as well as on data that arrived far in the past. Towards developing a solid foundation for practical rule-based stream reasoning, we propose and study in this paper a suite of decision problems that can be exploited by stream reasoning algorithms to tackle the aforementioned challenges, and provide tight complexity bounds for a core temporal extension of Datalog. All of the problems we consider can be solved at design time (under reasonable assumptions), prior to the processing of any data. Solving these problems enables the use of reasoning algorithms that process the input streams incrementally using a sliding window, while at the same time supporting an expressive rule-based knowledge representation language and minimising both latency and memory consumption
By Your Place in the World I Will Know Who You Are
No full textThis collection of personal essays, a first of its kind, re-imagines the idea of place for an emerging generation of readers and writers. It offers glimpses into where we are now and how that feels, and opens up the range and kinds of stories we can conceive of telling about living here. Contributors include Tony Ballantyne, Sally Blundell, Alex Calder, Annabel Cooper, Tim Corballis, Martin Edmond, Ingrid Horrocks, Lynn Jenner, Cherie Lacey, Tina Makereti, Harry Ricketts, Jack Ross, Alice Te Punga Somerville, Giovanni Tiso, Ian Wedde, Lydia Wevers, and Ashleigh Young.falseWellington, New Zealan
Optimising Ontology Classification.
No full textOntology classification - the computation of subsumption hierarchies for classes and properties - is one of the most important tasks for OWL reasoners. Based on the algorithm by Shearer and Horrocks [9], we present a new classification procedure that addresses several open issues of the original algorithm, and that uses several novel optimisations in order to achieve superior performance. We also consider the classification of (object and data) properties. We show that algorithms commonly used to implement that task are incomplete even for relatively weak ontology languages. Furthermore, we show how to reduce the property classification problem into a standard (class) classification problem, which allows reasoners to classify properties using our optimised procedure. We have implemented our algorithms in the OWL HermiT reasoner, and we present the results of a performance evaluation. © 2010 Springer-Verlag
Author interview: Q and A with Dr Ian Sanjay Patel on we’re here because you were there: immigration and the end of empire
No full textIn this author interview, we speak to Dr Ian Sanjay Patel about his new book, We’re Here Because You Were There: Immigration and the End of Empire, which explores post-war immigration laws, the afterlives of British imperial citizenship and related attempts to reimagine and rejuvenate British imperialism after 1945. Contributing to transnational histories of decolonisation, the book also explores the interconnections between human rights, post-war migration and international diplomacy. Author Interview with Dr Ian Sanjay Patel, author of We’re Here Because You Were There: Immigration and the End of Empire. Verso. 2021
URI Disambiguation in the Context of Linked Data
No full textThe Linked Data initiative has given rise to an increasing number of RDF datasets, many of which are freely accessible online. These resources often arise as a result of database exports; however sufficient consideration may not be given to the unseen implications caused when they are used in the wider context of the Semantic Web. This paper investigates two popular resources, DBLP and DBpedia, and discusses whether the issues regarding identity management and co-reference resolution have been suitably addressed. We find that a large percentage of authors in DBLP have been conflated, and that disambiguation pages have been incorrectly linked using owl:sameAs within DBpedia. Systems for dealing with these issues are presented, and directions are given for future research
Providence College Faculty Author Series 2017-2018: Ian Levy
No full textIn this installment of the Faculty Authors Series, Ian Levy (Theology, Providence College) discusses his newest book, Introducing Medieval Biblical Interpretation: The Senses of Scripture in Premodern Exegesis
Providence College Faculty Author Series 2017-2018: Ian Levy
No full textIn this installment of the Faculty Authors Series, Ian Levy (Theology, Providence College) discusses his newest book, Introducing Medieval Biblical Interpretation: The Senses of Scripture in Premodern Exegesis
Author interview: Q and A with Dr Paul Ian Campbell, author of education, retirement and career transitions for ‘black’ ex-professional footballers
No full textIn this author interview, we speak to Dr Paul Ian Campbell about his new book, Education, Retirement and Career Transitions for ‘Black’ Ex-Professional Footballers: ‘From Being Idolised to Stacking Shelves’, which explores black British male ex-professional footballers’ experiences of, and preparations for, retirement and career transition
A Description Logic with Transitive and Converse Roles and Role Hierarchies
No full textAus der Einleitung:
„As widely argued [Horrocks&Gough,1997; Sattler,1996], transitive roles play an important role in the adequate representation of aggregated objects: they allow these objects to be described by referring to their parts without specifying a level of decomposition. In [Horrocks&Gough,1997], the Description Logic (DL) ALCHR+ is presented, which extends ALC with transitive roles and a role hierarchy. It is argued in [Sattler,1998] that ALCHR+ is well-suited to the representation of aggregated objects in applications that require various part-whole relations to be distinguished, some of which are transitive. However, ALCHR+ allows neither the description of parts by means of the whole to which they belong, or vice versa. To overcome this limitation, we present the DL ALCHIR+ which allows the use of, for example, has part as well as is part of. To achieve this, ALCHR+ was extended with inverse roles.
It could be argued that, instead of defining yet another DL, one could make use of the results presented in [De Giacomo&Lenzerini,1996] and use ALC extended with role expressions which include transitive closure and inverse operators. The reason for not proceeding like this is the fact that transitive roles can be implemented more eficiently than the transitive closure of roles (see [Horrocks&Gough,1997]), although they lead to the same complexity class (ExpTime-hard) when added, together with role hierarchies, to ALC. Furthermore, it is still an open question whether the transitive closure of roles together with inverse roles necessitates the use of the cut rule [DeGiacomo&Massacci,1998], and this rule leads to an algorithm with very bad behaviour. We will present an algorithm for ALCHIR+ without such a rule.”An abridged version will appear in the Proceedings of the International Workshop on Description Logics, Trento, Italy, 1998
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