2 research outputs found
Complex question answering : minimizing the gaps and beyond
xi, 192 leaves : ill. ; 29 cmCurrent Question Answering (QA) systems have been significantly advanced in demonstrating
finer abilities to answer simple factoid and list questions. Such questions are easier
to process as they require small snippets of texts as the answers. However, there is
a category of questions that represents a more complex information need, which cannot
be satisfied easily by simply extracting a single entity or a single sentence. For example,
the question: “How was Japan affected by the earthquake?” suggests that the inquirer is
looking for information in the context of a wider perspective. We call these “complex questions”
and focus on the task of answering them with the intention to minimize the existing
gaps in the literature.
The major limitation of the available search and QA systems is that they lack a way of
measuring whether a user is satisfied with the information provided. This was our motivation
to propose a reinforcement learning formulation to the complex question answering
problem. Next, we presented an integer linear programming formulation where sentence
compression models were applied for the query-focused multi-document summarization
task in order to investigate if sentence compression improves the overall performance.
Both compression and summarization were considered as global optimization problems.
We also investigated the impact of syntactic and semantic information in a graph-based
random walk method for answering complex questions. Decomposing a complex question
into a series of simple questions and then reusing the techniques developed for answering
simple questions is an effective means of answering complex questions. We proposed a
supervised approach for automatically learning good decompositions of complex questions
in this work. A complex question often asks about a topic of user’s interest. Therefore, the
problem of complex question decomposition closely relates to the problem of topic to question
generation. We addressed this challenge and proposed a topic to question generation
approach to enhance the scope of our problem domain
Answering complex questions : supervised approaches
x, 108 leaves : ill. ; 29 cmThe term “Google” has become a verb for most of us. Search engines, however, have
certain limitations. For example ask it for the impact of the current global financial crisis
in different parts of the world, and you can expect to sift through thousands of results for
the answer. This motivates the research in complex question answering where the purpose
is to create summaries of large volumes of information as answers to complex questions,
rather than simply offering a listing of sources. Unlike simple questions, complex questions
cannot be answered easily as they often require inferencing and synthesizing information
from multiple documents. Hence, this task is accomplished by the query-focused multidocument
summarization systems. In this thesis we apply different supervised learning
techniques to confront the complex question answering problem. To run our experiments,
we consider the DUC-2007 main task.
A huge amount of labeled data is a prerequisite for supervised training. It is expensive
and time consuming when humans perform the labeling task manually. Automatic labeling
can be a good remedy to this problem. We employ five different automatic annotation
techniques to build extracts from human abstracts using ROUGE, Basic Element (BE) overlap,
syntactic similarity measure, semantic similarity measure and Extended String Subsequence
Kernel (ESSK). The representative supervised methods we use are Support Vector
Machines (SVM), Conditional Random Fields (CRF), Hidden Markov Models (HMM) and
Maximum Entropy (MaxEnt). We annotate DUC-2006 data and use them to train our systems,
whereas 25 topics of DUC-2007 data set are used as test data. The evaluation results
reveal the impact of automatic labeling methods on the performance of the supervised approaches
to complex question answering. We also experiment with two ensemble-based
approaches that show promising results for this problem domain