= A User Interface for the QLever SPARQL+Text engine (project or theses) =

'''Type:''' This is well-suited as a project (B.Sc. or M.Sc.) but also provides ample opportunity for continuation with a theses (B.Sc. or M.Sc). You should be fond of good user interfaces and have a good taste concerning layout and colors and such things. You should also like knowledge bases and big datasets and searching in them.   

'''Background info:''' Broccoli is our current system for convenient semantic search on text combined with a knowledge base. Here is a [[http://broccoli.informatik.uni-freiburg.de|demo]]. The demo is described in [1]. Broccoli works with a special backend, which only supports a particular subset of queries (in a nutshell: treelike SPARQL queries with a text-search component). The backend also has its own peculiar and non-standard syntax. The backend is described in [4]. In the meantime, we have developed a full-featured SPARQL+Text engine, called QLever [1]. QLever supports full SPARQL queries with a text-search component. However, the current UI is very simplistic and hard to use: it's a essentially a text field, where one can enter a SPARQL query, and then one gets a table with the result tuples. Here is a  link to an [[http://vulcano.informatik.privat:7001|internal demo (only works with an IP address from the technical faculty)]], which searches the Freebase knowledge base in combination with the !ClueWeb12 web corpus. An example query for copy&paste is given under [5].
 
'''Goal''': design a front-end for QLever that makes it easy to ask SPARQL+Text queries, also without prior knowledge of the entity and predicate names of the underlying knowledge base (in the demos above: Freebase). The user interface should be simpler than that for Broccoli.

'''Subgoal 1''': Broccoli has four boxes with suggestions, see the demo linked above. This confused users a lot. One of the main tasks will be to devise a simpler interface, but that is still powerful enough to formulate all queries.

'''Subgoal 2''': One problem with the current Broccoli interface is that the user has to know what is a predicate and what is an object. However, this depends a lot on how the statements are represented in the knowledge base. Which is not something the user can or is supposed to know a priori. TODO: give an example. It would be better to provide completions for a predicate combined with an object at the same time.







[1] H. Bast and B. Buchhold. QLever: a Query Engine for Efficient SPARQL+Text Search. Paper currently under review. [[https://github.com/Buchhold/QLever|Code and setup instructions on GitHub]]

[2] H. Bast, F. Bäurle, B. Buchhold, E. Haußmann. [[http://ad-publications.informatik.uni-freiburg.de/SIGIR_broccoli_BBBH_2014.pdf|Semantic Full-Text Search with Broccoli (Demo paper)]]. SIGIR 2014: 1265-1266

[3] H. Bast, F. Bäurle, B. Buchhold, E. Haußmann. [[http://ad-publications.informatik.uni-freiburg.de/CoRR_Broccoli_BBBH_2013.pdf|Broccoli: Semantic Full-Text Search at your Fingertips (System and Evaluation Paper)]]. CoRR abs/1207.2615 (2012)

[4] H. Bast and B. Buchhold. [[http://ad-publications.informatik.uni-freiburg.de/CIKM_broindex_BB_2013.pdf|An index for efficient semantic full-text search]]. CIKM 2013: 369-378

[5] Example SPARQL+Text query (astronauts who walked on the moon) for copy&paste to the text field of the QLever demo:

{{{
PREFIX fb: <http://rdf.freebase.com/ns/>
SELECT ?person ?name TEXT(?c) SCORE(?c) WHERE {
  ?person fb:people.person.profession ?profession .
  ?profession fb:type.object.name.en "Astronaut" .
  ?person fb:type.object.name.en ?name .
  ?person <in-context> ?c .
  ?c <in-context> walk* moon
}
LIMIT 100
ORDER BY DESC(SCORE(?c))
}}}