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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Overview of CLEF QA Entrance Exams Task 2014</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Anselmo Peñas</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yusuke Miyao</string-name>
          <email>yusuke@nii.ac.jp</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Álvaro Rodrigo</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Eduard Hovy</string-name>
          <email>hovy@cmu.edu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Noriko Kando</string-name>
          <email>kando@nii.ac.jp</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Carnegie Mellon University</institution>
          ,
          <country country="US">USA</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>NLP&amp;IR group</institution>
          ,
          <addr-line>UNED</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>National Institute of Informatics</institution>
          ,
          <country country="JP">Japan</country>
        </aff>
      </contrib-group>
      <fpage>1194</fpage>
      <lpage>1200</lpage>
      <abstract>
        <p>This paper describes the Entrance Exams task at the CLEF QA Track 2014. Following 2013 edition, the data set has been extracted from actual university entrance examinations including a variety of topics and question types. Systems receive a set of Multiple-Choice Reading Comprehension tests where the task is to select the correct answer among a finite set of candidates, according to the given text. Questions are designed originally for testing human examinees, rather than evaluating computer systems. Therefore, the data set challenges human ability to show their understanding of texts. Thus, questions and answers are lexically distant from their supporting excerpts in text, requiring not only a high degree of textual inference, but also the development of strategies for selecting the correct answer. As a novelty this year, data sets originally in English were manually translated into Russian, French, Spanish and Italian.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>INTRODUCTION</title>
      <p>Following 2013 edition, the Entrance Exams task at CLEF QA Track 2014 is focused
on solving Reading Comprehension tests of English examinations. Reading
Comprehension tests are routinely used to assess the degree to which people comprehend
what they read, so we work with the hypothesis that it is reasonable to use these tests
to assess the degree to which a machine “comprehends” what it is reading. Despite the
difficulty of the challenge, we believe we are building a real benchmark that will
serve to measure real progress in the field during the next years.</p>
      <p>With this goal in mind, CLEF and NTCIR started collaboration in 2013
around the idea of testing systems against University Entrance Exams, the same
exams humans have to pass to enter University. The data set was prepared and
distributed by NTCIR, while other organization efforts, including announcements, collecting
and evaluating submissions, etc. were managed by CLEF. The success of this
coordination also owes to the standard data format and evaluation methodology followed in
past editions.</p>
    </sec>
    <sec id="sec-2">
      <title>TASK DESCRIPTION</title>
      <p>Participant systems are asked to read a given document and answer a set of questions.
Questions are given in multiple-choice format, with several options from which a
single answer must be selected. Systems have to answer questions by referring to
"common sense knowledge" that high school students who aim to enter the university
are expected to have. Another important difference is that we do not intend to restrict
question types. Any type of reading comprehension questions in real entrance exams
will be included in the test data.
3</p>
    </sec>
    <sec id="sec-3">
      <title>DATA 3.1</title>
    </sec>
    <sec id="sec-4">
      <title>Sources</title>
      <p>Japanese University Entrance Exams include questions formulated at various levels of
complexity and test a wide range of capabilities. The challenge of "Entrance Exams"
aims at evaluating systems under the same conditions that humans are evaluated to
enter the University.</p>
      <p>The data set is extracted from standardized English examinations for
university admission in Japan. Exams are created by the Japanese National Center for
University Admissions Tests. Original examinations include various styles of questions,
such as word filling, grammatical error recognition, sentence filling, etc.</p>
      <p>One of such styles is reading comprehension; a test provides a text that
describes some daily life situation, and questions about the text are asked. As in the
previous edition, we reduced the challenge to these Reading Comprehension exercises
contained in the English exams, leaving other types of exercises available for future
tasks.</p>
      <p>For each examination, one text is given, and five questions on the given text
are asked. Each question has four choices. For this year campaign, we reused as
development data 12 examinations from last year campaign. Besides, we provided
new 12 documents, 60 questions and 240 candidate answers to be validated.
3.2</p>
    </sec>
    <sec id="sec-5">
      <title>Languages</title>
      <p>As a novelty this year, data sets for development and testing originally in English
were manually translated into Russian, French, Spanish and Italian. They are parallel
translations of texts, questions and candidate answers.</p>
      <p>
        In addition to the official data, we collected four more unoffcial translations
into French. Despite they preserve original meaning, each translation has its
particularities that produce different effects on systems performance: text simplification, lexical
variation, different uses of anaphora, overall quality, etc. This data is extremely useful
to get insights about systems and their level of inference. Synapse [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] reports some
initial experiments with this unofficial data.
      </p>
      <p>EVALUATION
Scoring of the output produced by participant systems was performed automatically
by comparing the answers of systems against the gold standard collection with
annotations made by humans. No manual assessment was performed.</p>
      <p>
        Each test receives an evaluation score between 0 and 1 using c@1 [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. This
measure, used in previous CLEF QA Tracks, encourages systems to reduce the
number of incorrect answers while maintaining the number of correct ones by leaving
some questions unanswered. Systems received evaluation scores from two different
perspectives:
1. At the question-answering level: correct answers are counted individually
without grouping them
2. At the reading-test level: figures for each reading test as a whole are given.
      </p>
      <p>A test is considered to be passed if a c@1 score above 0.5 is reached. Then,
the proportion of tests that are passed is given as a global score.
5</p>
    </sec>
    <sec id="sec-6">
      <title>RESULTS</title>
      <p>csgs-2
cicnlp-2
cicnlp-3
cicnlp-4
cicnlp-1
cicnlp-6
DIPF-5</p>
      <p>DIPF-3
LIMSI-4-HR</p>
      <p>LIMSI-7
LIMSI-4
DIPF-6</p>
      <p>Random
LIMSI-2-Inv</p>
      <p>DIPF-4
cicnlp-5
LIMSI-2
DIPF-2</p>
      <p>DIPF-1
LIMSI-1-dude1</p>
      <p>LIMSI-3</p>
      <p>LIMSI-5
LIMSI-1-dude</p>
      <p>LIMSI-6</p>
      <p>
        According to Table 2, the system with higher score (Synapse for French [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]) is
the unique system that answered more questions correctly than incorrectly. Only few
runs made use of the leaving questions unanswered option. In these cases, despite
some systems reduced considerably the amount of incorrect answers, none of them
could improve their overall c@1 score.
      </p>
      <p>Table 3 shows results for the reading perspective. First column corresponds to
systems run id, second column to the overall c@1 obtained, third column shows the
number of tests that the systems have passed if we consider the threshold of 0.5, and
the rest of columns correspond to the c@1 value for each particular test.
The results observed under the reading perspective are very encouraging. The three
top systems were able to pass at least half of tests. As observed in Table 4, each test
has a different degree of difficulty for the systems. There are three main reasons for
that: the way the questions are formulated, the lexical gap between the text and the
candidate answers, and the inherit difficulty of some questions for which wrong
candidate answers seems to be closer to the supporting text in a light reading.</p>
      <p>An overall overview of systems' descriptions shows the importance given to
answer ranking over validation. In fact, all participant systems relied on ranking
methods except the LIMSI-CNRS group, which applied an approach based on
validation.</p>
      <p>We found two different approaches regarding the use of documents for
finding the correct answer: on one hand, some systems work with the whole document
while on the other hand, some systems select a set of promising text snippets using
retrieval techniques. We do not see observation about the best performance of one
approach over the other.</p>
      <p>Some participants create hypotheses combining questions and candidates,
and trying to match these hypotheses with the document excerpts.</p>
      <p>
        All participants except [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] reported the use of coreference analysis in their
systems, pointing out the importance of this information.
6
      </p>
    </sec>
    <sec id="sec-7">
      <title>SUMMARY OF SYSTEMS</title>
      <p>
        DIPF system [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] retrieves a set of sentences from the document that are likely to
contain a correct answer according to a set of lexical and semantic similarity measures.
Each candidate answer is combined with the question to form a hypothesis to be
checked against the selected sentences. The final decision about the selected answer
relies on a linear combination of two scores for each Text-Hypothesis pair: (1) the
confidence score given by a state of the art RTE system and; (2) a combination of
lexical and semantic similarity measures.
      </p>
      <p>
        Synapse Dèveloppement [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ][
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] builds Clause Description Structures (CDS)
for documents, questions and answers, and compares them in order to take the final
decision. CDSs represent a rich structure containing semantic information of texts, as
well as relations among the elements of the text. The system first removes candidate
answers that do not match the expected answer type. Then it uses CDSs to compute
the number of common elements and their proximity between documents and
candidate answers. This value is used to rank the candidate answers and select the first one.
      </p>
      <p>
        CICNLP system [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ] combines questions with candidate answers to build
hypotheses. First, the system generates graph representations for the hypotheses and
documents based on syntactic analysis. Paths sharing initial and final nodes both in
text and hypothesis are converted into linguistic features for vector representation.
Finally, the system uses these vectors for computing the cosine similarity, and ranking
the candidate answers.
      </p>
      <p>
        CSGS system [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] is based on weighting the alignment of text sentences and
question answers at token and chunk level.
      </p>
      <p>
        LIMSI-CNRS system [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] relies on a validation approach in contrast to
ranking methods used by other participants. First, the system uses the question and its
expansion to retrieve passages of 3 to 5 sentences. Second, the system creates
predicate-argument structures for passages and candidate answers, trying to align them at
the word level using semantic relations. Then, the system applies a set of validation
and invalidation rules. A candidate answer is validated if it fires all the validation
rules and does not fire any invalidation rule. If there is more than one answer after the
validation process, the system selects the answer with the highest alignment score.
Validation and invalidation rules were made manually over information on subjects,
predicates and arguments, as well as predicate truth values given by TruthTeller [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ].
7
      </p>
    </sec>
    <sec id="sec-8">
      <title>CONCLUSIONS</title>
      <p>Last year exercise experience suggested the need to develop strategies to reject
answers more than strategies to accept answers. One system started to develop this
strategy but results aren’t yet among the top performers. All systems except Synapse’s for
French select more incorrect answers than correct ones. This is really a measure of
progress in systems development. However, at the reading perspective evaluation, we
have already three systems (two teams) able to pass at least half of reading tests.</p>
      <p>Again, the Entrance Exams task shows that Question Answering is a task far
from being solved. However, it provides a real benchmark able to assess real progress
in the field along future years.</p>
    </sec>
    <sec id="sec-9">
      <title>ACKNOWLEDGEMENTS</title>
      <p>The collaboration has been developed in the framework of Todai Robot Project in
Japan, and the CHIST-ERA Readers project in Europe (MINECO
PCIN-2013-002C02-01). The Todai Robot Project is a grand challenge headed by NII, and aims to
develop an end-to-end AI system that can solve real entrance examinations of
universities in Japan integrating heterogeneous AI technologies, such as natural language
processing, situation understanding, math formula processing or vision processing.</p>
    </sec>
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