University of Leipzig AKSW Homepage | Blog |

Archiv für die Kategorie 'Projects'

AKSW Colloquium: Edgard Marx and Tommaso Soru on Monday, February 23, 3.00 p.m.

February 19, 2015 - 10:53 pm by TommasoSoru - No comments »

On Monday, 23rd of February 2015, Edgard Marx will introduce Smart, a search engine designed over the Semantic Search paradigm; subsequently, Tommaso Soru will present ROCKER, a refinement operator approach for key discovery.

EDIT: Tommaso Soru’s presentation was moved to March 2nd.

Abstract – Smart

Since the conception of the Web, search engines play a key role in making content available. However, retrieving of the desire information is still significantly challenging. Semantic Search systems are a natural evolution of the traditional search engines. They promise more accurate interpretation by understanding the contextual meaning of the user query. In this talk, we will introduce our audience to Smart, a search engine designed over the Semantic Search paradigm. Smart incorporates two of our currently designed approaches of dealing with the problem of Information Retrieval, as well as a novel interface paradigm. Moreover, we will present some of the former, as well as more recent state-of-the-art approaches used by the industry – for instance by Yahoo!, Google and Facebook.

Abstract – ROCKER

As within the typical entity-relationship model, unique and composite keys are of central importance also when their concept is applied on the Linked Data paradigm. They can provide help in manifold areas, such as entity search, question answering, data integration and link discovery. However, the current state of the art does not count approaches able to scale while relying on a correct definition of key. We thus present a refinement-operator-based approach dubbed ROCKER, which has shown to scale to big datasets with respect to the run time and the memory consumption. ROCKER will be officially introduced at the 24th International Conference on World Wide Web.

Tommaso Soru, Edgard Marx, and Axel-Cyrille Ngonga Ngomo, “ROCKER – A Refinement Operator for Key Discovery”. [PDF]

DL-Learner 1.0 (Supervised Structured Machine Learning Framework) Released

February 13, 2015 - 10:38 am by Jens Lehmann - No comments »

Dear all,

we are happy to announce DL-Learner 1.0.

DL-Learner is a framework containing algorithms for supervised machine learning in RDF and OWL. DL-Learner can use various RDF and OWL serialization formats as well as SPARQL endpoints as input, can connect to most popular OWL reasoners and is easily and flexibly configurable. It extends concepts of Inductive Logic Programming and Relational Learning to the Semantic Web in order to allow powerful data analysis.

Website: http://dl-learner.org
GitHub page: https://github.com/AKSW/DL-Learner
Download: https://github.com/AKSW/DL-Learner/releases
ChangeLog: http://dl-learner.org/development/changelog/

DL-Learner is used for data analysis in other tools such as ORE and RDFUnit. Technically, it uses refinement operator based, pattern based and evolutionary techniques for learning on structured data. For a practical example, see http://dl-learner.org/community/carcinogenesis/. It also offers a plugin for Protege, which can give suggestions for axioms to add. DL-Learner is part of the Linked Data Stack – a repository for Linked Data management tools.

We want to thank everyone who helped to create this release, in particular (alphabetically) An Tran, Chris Shellenbarger, Christoph Haase, Daniel Fleischhacker, Didier Cherix, Johanna Völker, Konrad Höffner, Robert Höhndorf, Sebastian Hellmann and Simon Bin. We also acknowledge support by the recently started SAKE project, in which DL-Learner will be applied to event analysis in manufacturing use cases, as well as the GeoKnow and Big Data Europe projects where it is part of the respective platforms.

Kind regards,

Lorenz Bühmann, Jens Lehmann and Patrick Westphal

Writing a Survey – Steps, Advantages, Limitations and Examples

- 10:10 am by AmrapaliZaveri - No comments »

What is a Survey?

A survey or systematic literature review is a text of a scholarly paper, which includes the current knowledge including substantive findings, as well as theoretical and methodological contributions to a particular topic. Literature reviews use secondary sources, and do not report new or original experimental work [1].

A systematic review is a literature review focused on a research question, trying to identify, appraise, select and synthesize all high quality research evidence and arguments relevant to that question. Moreover, a literature review is comprehensive, exhaustive and repeatable, that is, the readers can replicate or verify the review.

Steps to perform a survey

  • Select two independent reviewers

  • Look for related/existing surveys

    • If it exists, see how long back it was done. If it was 10 years ago, you can go ahead and update it.

  • Formulate research questions

  • Devise eligibility criteria

  • Define search strategy – keywords, journals, conferences, workshops to search in

  • Retrieve further potential article using search strategy and also directly contacting top researchers in the field

  • Compare chosen articles among reviewers and decide a core set of papers to be included in the survey

  • Perform Qualitatively and Quantitatively on the selected set of papers

  • Report on the results

Advantages of writing a survey

There are several benefits/advantages of conducting a survey, such as:

  • A survey is the best way to get an idea of the state-of-the-art technologies, algorithms, tools etc. in a particular field

  • One can get a clear birds-eye overview of the current state of that field

  • It can serve as a great starting point for a student or any researcher thinking of venturing into that particular field/area of research

  • One can easily acquire updated information of a subject by referring to a review

  • It gives researchers the opportunity to formalize different concepts of a particular field

  • It allows one to identify challenges and gaps that are unanswered and crucial for that subject

Limitations of a survey

However, there are a few limitations that must be considered before undertaking a survey such as:

  • Surveys can tend to be biased, thus it is necessary to have two researchers, who perform the systematic search for the articles independently

  • It is quite challenging to unify concepts, especially when there are different ideas referring to the same concepts developed over several years

  • Indeed, conducting a survey and getting the article published is a long process

Surveys conducted by members of the AKSW group

In our group, three students conducted comprehensive literature reviews on three different topics:

  • Linked Data Quality: The survey covers 30 core papers, which focus on providing quality assessment methodologies for Linked Data specifically. A total of 18 data quality dimensions along with their definitions and 69 metrics are provided. Additionally, the survey contributes a comparison of 12 tools, which perform quality assessment of Linked Data [2].

  • Ubiquitous Semantic Applications: The survey presents a thorough analysis of 48 primary studies out of 172 initially retrieved papers.  The results consist of a comprehensive set of quality attributes for Ubiquitous Semantic Applications together with corresponding application features suggested for their realization. The quality attributes include aspects such as mobility, usability, heterogeneity, collaboration, customizability and evolvability. The proposed quality attributes facilitate the evaluation of existing approaches and the development of novel, more effective and intuitive Ubiquitous Semantic Applications [3].

  • User interfaces for semantic authoring of textual content: The survey covers a thorough analysis of 31 primary studies out of 175 initially retrieved papers. The results consist of a comprehensive set of quality attributes for SCA systems together with corresponding user interface features suggested for their realization. The quality attributes include aspects such as usability, automation, generalizability, collaboration, customizability and evolvability. The proposed quality attributes and UI features facilitate the evaluation of existing approaches and the development of novel more effective and intuitive semantic authoring interfaces [4].

Also, here is a presentation on “Systematic Literature Reviews”: http://slidewiki.org/deck/57_systematic-literature-review.

References

[1] Lisa A. Baglione (2012) Writing a Research Paper in Political Science. Thousand Oaks: CQ Press.

[2] Amrapali Zaveri, Anisa Rula, Andrea Maurino, Ricardo Pietrobon, Jens Lehmann and Sören Auer (2015), ‘Quality Assessment for Linked Data: A Survey’, Semantic Web Journal. http://www.semantic-web-journal.net/content/quality-assessment-linked-data-survey

[3] Timofey Ermilov, Ali Khalili, and Sören Auer (2014). ;Ubiquitous Semantic Applications: A Systematic Literature Review’. Int. J. Semant. Web Inf. Syst. 10, 1 (January 2014), 66-99. DOI=10.4018/ijswis.2014010103 http://dx.doi.org/10.4018/ijswis.2014010103

[4] Ali Khalili and Sören Auer (2013). ‘User interfaces for semantic authoring of textual content: A systematic literature review’, Web Semantics: Science, Services and Agents on the World Wide Web, Volume 22, October 2013, Pages 1-18 http://www.sciencedirect.com/science/article/pii/S1570826813000498

Kick-Off for the BMWi project SAKE

February 3, 2015 - 11:39 am by Ricardo Usbeck - No comments »

Hi all!

One of AKSW’s Big Data Project, SAKE – Semantische Analyse Komplexer Ereignisse (SAKE – Semantic Analysis of Complex Events) kicked-off in Karlsruhe. SAKE is one of the winners of the Smart Data Challenge and is funded by the German BMWi (Bundesministerium für Wirtschaft und Energie) and has a duration of 3 years. Within this project, AKSW will develop powerful methods for analysis of industrial-scale Big Linked Data in real time. To this end, the team will extend existing frameworks like LIMES, DL-Learner, QUETSAL and FOX. Together with USU AG, Heidelberger Druckmaschinen, Fraunhofer  IAIS and AviComp Controls novel methods for tackling Business Intelligence challenges will be devised.

More info to come soon!

Stay tuned!

Axel on behalf of the SAKE team

Two AKSW Papers at #WWW2015 in Florence, Italy

January 20, 2015 - 4:09 pm by Ricardo Usbeck - No comments »

Hello Community!
We are very pleased to announce that two of our papers were accepted for presentation at WWW 2015.  The papers cover novel approaches for Key Discovery while Linking Ontologies and a benchmark framework for entity annotation systems. In more detail, we will present the following papers:
Visit us from the 18th to the 22nd May in Florence, Italy and enjoy the talks. More information on these publications at http://aksw.org/Publications.
Cheers,
Ricardo on behalf of AKSW