Nikolaos Lagos

Designing for Inconsistency – The Dependency-Based PERICLES Approach

The rise of the Semantic Web has provided cultural heritage researchers and practitioners with several tools for ensuring semantic-rich representations and interoperability of cultural heritage collections. Although indeed offering a lot of advantages, these tools, which come mostly in the form of ontologies and related vocabularies, do not provide a conceptual model for capturing contextual and environmental dependencies contributing to long-term digital preservation. This paper presents one of the key outcomes of the PERICLES FP7 project, the Linked Resource Model, for modelling dependencies as a set of evolving linked resources. The proposed model is evaluated via a domain-specific representation involving digital video art.

Event Extraction for Legal Case Building and Reasoning

We are interested in developing tools to support the activities of lawyers in corporate litigation. In current applications, information such as characters that have played a significant role in a case, events in which they have participated, people they have been in contact, etc., have to be manually identified. There is little in the way of support to help them identify the relevant information in the first place. In this paper, we describe an approach to semi-automatically extracting such information from the collection of documents the lawyers are searching. Our approach is based on Natural Language Processing techniques and it enables the use of entity related information corresponding to the relations among the key players of a case, extracted in the form of events.

On the Preservation of Evolving Digital Content – The Continuum Approach and Relevant Metadata Models

We consider the preservation of digital objects in continually evolving ecosystems, for which traditional lifecycle approaches are less appropriate. Motivated by the Records Continuum theory, we define an approach that combines active life with preservation and is non-custodial, which we refer to as the continuum approach. Preserving objects and their associated environment introduces high level of complexity. We therefore describe a model-driven approach, termed the Continuum approach, in which models rather than the digital objects themselves can be analysed. In such setting, the use of appropriate metadata is very important, we therefore outline the PERICLES Linked Resource Model, an upper ontology for modelling digital ecosystems, and compare and contrast it to the Australian Government Recordkeeping Metadata Standard, developed within the record keeping community.

Multi-Context Systems for Consistency Validation and Querying of Business Process Models

Large organizations today face a growing challenge of managing heterogeneous process collections containing business processes. Explicit semantics inherent to domain-specific models can help alleviate some of the management challenges. Starting with concept definitions, designers can create domain specific processes and eventually generate industry-standard BPMN for use in BPMS solutions. However, in such a multi-layered setting, any of these artefacts (concepts, domain processes and BPMN) can be modified by various stakeholders and changes done by one person may influence models used by others. There is therefore a need for tool support to aid in keeping track of changes done and their impacts on different stakeholders. In this paper, we present a multi-context systems based approach that allows inferring impacts of changes, especially in terms of consistency, and executing semantic queries. In contrast to existing work, our framework allows the co-existence of different formalisms, with potentially different characteristics, offering greater flexibility in knowledge base and tool integration.

Enriching How-to Guides by Linking Actionable Phrases

The World Wide Web contains a large number of community created knowledge of instructional nature. Similarly, in a commercial setting, databases of instructions are used by customer-care providers to guide clients in the resolution of issues. Most of these instructions are expressed in natural language. Knowledge Bases including such information are valuable through the sum of their single entries. However, as each entry is created mostly independently, users (e.g. other community members) cannot take advantage of the accumulated knowledge that can be developed via the aggregation of related entries. In this paper we consider the problem of inter-linking Knowledge Base entries, in order to get relevant information from other parts of the Knowledge Base. To achieve this, we propose to detect \textit{actionable phrases} -- text fragments that describe how to perform a certain action -- and link them to other entries. The extraction method that we implement achieves an F-score of 67.35\%. We also show that using actionable phrases results in better linking quality than using coarser-grained spans of text, as proposed in the literature. Besides the evaluation of both steps, we also include a detailed error analysis and release our annotation to the community.

Identifying User Issues and Request Types in Forum Question Posts Based on Discourse Analysis

In this paper we propose the detection of user issues and request types in technical forum question posts with a twofold purpose: supporting up-to-date knowledge generation in organizations that provide (semi-) automated customer-care services, and enriching forum metadata in order to enhance the effectiveness of search. We present a categorization system for detecting the proposed question post types based on discourse analysis, and show the advantage of using discourse patterns compared to a baseline relying on standard linguistic features. Besides the detailed description of our method, we also release our annotated corpus to the community.

Preserving Consistency in Domain-Specific Business Processes Through Semantic Representation of Artefacts

Large organizations today face a growing challenge of managing heterogeneous process collections containing business processes. Explicit semantics inherent to domain-specific models can help alleviate some of the management challenges. Starting with concept definitions, designers can create domain specific processes and eventually generate industry-standard BPMN for use in BPMS solutions. However, any of these artefacts (concepts, domain processes and BPMN) can be modified by various stakeholders and changes done by one person may influence models used by others. There is therefore a need for tool support to aid in keeping track of changes done and their impacts on different stakeholders. In this paper we present an approach towards providing such support based on a semantic layer that records the provenance of the information and accordingly propagates impacts of changes to related resources, and illustrate the applicability of the approach via an illustrative example.

Semantic version management based on formal certification

This paper describes a Semantic Version Management method that enables managing consistently digital resources throughout their life cycle. The core notion is that resources are described be means of logical specifications formally expressed using an extensible logical language. A new version is considered certified only if the resource owner is able to formally prove that it satisfies its logical specification. The method includes formal proofs for qualifying changes (occurring either on the resource content or on the corresponding specifications) and accordingly characterizing them via the definition of appropriate version labels. Based on the above method, a service-oriented solution is also described that enables managing changes consistently, in a sound manner, for both resource owners and users.

Dependency modelling for inconsistency management in Digital Preservation – The PERICLES approach

The rise of the Semantic Web has provided cultural heritage researchers and practitioners with several tools for providing semantically rich representations and interoperability of cultural heritage collections. Although indeed offering a lot of advantages, these tools, which come mostly in the form of ontologies and related vocabularies, do not provide a conceptual model for capturing contextual and environmental dependencies, contributing to long-term digital preservation. This paper presents one of the key outcomes of the PERICLES FP7 project, the Linked Resource Model, for modelling dependencies as a set of evolving linked resources. The adoption of the proposed model and the consistency of its representation are evaluated via a specific instantiation involving the domain of digital video art.

The Resource Action Language: Towards Designing Reactive RDF Stores

In an interconnected world such as the one envisioned by pervasive computing, systems should be able to react to stimuli received from the environment in a streaming fashion. Reactions may include not only performing local updates, but also sending and asking for information from other systems, waiting for responses, and requesting for changes. In this paper we give a short introduction to the main principles of a language we are developing to achieve that, ReAL. Key elements of ReAL in that context include the introduction of explicit operators to deal with concurrency, nested transactions, and streams. Based on these operators we show how interaction with external services could be enabled. In the future we plan to evaluate further the most innovative operators, define the semantics of ReAL, and analyze its relation to SPARQL, the standard Semantic Web query language.