14,337 research outputs found
Answering Complex Questions by Joining Multi-Document Evidence with Quasi Knowledge Graphs
Direct answering of questions that involve multiple entities and relations is a challenge for text-based QA. This problem is most pronounced when answers can be found only by joining evidence from multiple documents. Curated knowledge graphs (KGs) may yield good answers, but are limited by their inherent incompleteness and potential staleness. This paper presents QUEST, a method that can answer complex questions directly from textual sources on-the-fly, by computing similarity joins over partial results from different documents. Our method is completely unsupervised, avoiding training-data bottlenecks and being able to cope with rapidly evolving ad hoc topics and formulation style in user questions. QUEST builds a noisy quasi KG with node and edge weights, consisting of dynamically retrieved entity names and relational phrases. It augments this graph with types and semantic alignments, and computes the best answers by an algorithm for Group Steiner Trees. We evaluate QUEST on benchmarks of complex questions, and show that it substantially outperforms state-of-the-art baselines
Strong Baselines for Simple Question Answering over Knowledge Graphs with and without Neural Networks
We examine the problem of question answering over knowledge graphs, focusing
on simple questions that can be answered by the lookup of a single fact.
Adopting a straightforward decomposition of the problem into entity detection,
entity linking, relation prediction, and evidence combination, we explore
simple yet strong baselines. On the popular SimpleQuestions dataset, we find
that basic LSTMs and GRUs plus a few heuristics yield accuracies that approach
the state of the art, and techniques that do not use neural networks also
perform reasonably well. These results show that gains from sophisticated deep
learning techniques proposed in the literature are quite modest and that some
previous models exhibit unnecessary complexity.Comment: Published in NAACL HLT 201
Joint Video and Text Parsing for Understanding Events and Answering Queries
We propose a framework for parsing video and text jointly for understanding
events and answering user queries. Our framework produces a parse graph that
represents the compositional structures of spatial information (objects and
scenes), temporal information (actions and events) and causal information
(causalities between events and fluents) in the video and text. The knowledge
representation of our framework is based on a spatial-temporal-causal And-Or
graph (S/T/C-AOG), which jointly models possible hierarchical compositions of
objects, scenes and events as well as their interactions and mutual contexts,
and specifies the prior probabilistic distribution of the parse graphs. We
present a probabilistic generative model for joint parsing that captures the
relations between the input video/text, their corresponding parse graphs and
the joint parse graph. Based on the probabilistic model, we propose a joint
parsing system consisting of three modules: video parsing, text parsing and
joint inference. Video parsing and text parsing produce two parse graphs from
the input video and text respectively. The joint inference module produces a
joint parse graph by performing matching, deduction and revision on the video
and text parse graphs. The proposed framework has the following objectives:
Firstly, we aim at deep semantic parsing of video and text that goes beyond the
traditional bag-of-words approaches; Secondly, we perform parsing and reasoning
across the spatial, temporal and causal dimensions based on the joint S/T/C-AOG
representation; Thirdly, we show that deep joint parsing facilitates subsequent
applications such as generating narrative text descriptions and answering
queries in the forms of who, what, when, where and why. We empirically
evaluated our system based on comparison against ground-truth as well as
accuracy of query answering and obtained satisfactory results
Out of the Box: Reasoning with Graph Convolution Nets for Factual Visual Question Answering
Accurately answering a question about a given image requires combining
observations with general knowledge. While this is effortless for humans,
reasoning with general knowledge remains an algorithmic challenge. To advance
research in this direction a novel `fact-based' visual question answering
(FVQA) task has been introduced recently along with a large set of curated
facts which link two entities, i.e., two possible answers, via a relation.
Given a question-image pair, deep network techniques have been employed to
successively reduce the large set of facts until one of the two entities of the
final remaining fact is predicted as the answer. We observe that a successive
process which considers one fact at a time to form a local decision is
sub-optimal. Instead, we develop an entity graph and use a graph convolutional
network to `reason' about the correct answer by jointly considering all
entities. We show on the challenging FVQA dataset that this leads to an
improvement in accuracy of around 7% compared to the state of the art.Comment: Accepted to NIPS 201
Cognitive Graph for Multi-Hop Reading Comprehension at Scale
We propose a new CogQA framework for multi-hop question answering in
web-scale documents. Inspired by the dual process theory in cognitive science,
the framework gradually builds a \textit{cognitive graph} in an iterative
process by coordinating an implicit extraction module (System 1) and an
explicit reasoning module (System 2). While giving accurate answers, our
framework further provides explainable reasoning paths. Specifically, our
implementation based on BERT and graph neural network efficiently handles
millions of documents for multi-hop reasoning questions in the HotpotQA
fullwiki dataset, achieving a winning joint score of 34.9 on the
leaderboard, compared to 23.6 of the best competitor.Comment: ACL 201
Data Science with Vadalog: Bridging Machine Learning and Reasoning
Following the recent successful examples of large technology companies, many
modern enterprises seek to build knowledge graphs to provide a unified view of
corporate knowledge and to draw deep insights using machine learning and
logical reasoning. There is currently a perceived disconnect between the
traditional approaches for data science, typically based on machine learning
and statistical modelling, and systems for reasoning with domain knowledge. In
this paper we present a state-of-the-art Knowledge Graph Management System,
Vadalog, which delivers highly expressive and efficient logical reasoning and
provides seamless integration with modern data science toolkits, such as the
Jupyter platform. We demonstrate how to use Vadalog to perform traditional data
wrangling tasks, as well as complex logical and probabilistic reasoning. We
argue that this is a significant step forward towards combining machine
learning and reasoning in data science
Neural Architecture for Question Answering Using a Knowledge Graph and Web Corpus
In Web search, entity-seeking queries often trigger a special Question
Answering (QA) system. It may use a parser to interpret the question to a
structured query, execute that on a knowledge graph (KG), and return direct
entity responses. QA systems based on precise parsing tend to be brittle: minor
syntax variations may dramatically change the response. Moreover, KG coverage
is patchy. At the other extreme, a large corpus may provide broader coverage,
but in an unstructured, unreliable form. We present AQQUCN, a QA system that
gracefully combines KG and corpus evidence. AQQUCN accepts a broad spectrum of
query syntax, between well-formed questions to short `telegraphic' keyword
sequences. In the face of inherent query ambiguities, AQQUCN aggregates signals
from KGs and large corpora to directly rank KG entities, rather than commit to
one semantic interpretation of the query. AQQUCN models the ideal
interpretation as an unobservable or latent variable. Interpretations and
candidate entity responses are scored as pairs, by combining signals from
multiple convolutional networks that operate collectively on the query, KG and
corpus. On four public query workloads, amounting to over 8,000 queries with
diverse query syntax, we see 5--16% absolute improvement in mean average
precision (MAP), compared to the entity ranking performance of recent systems.
Our system is also competitive at entity set retrieval, almost doubling F1
scores for challenging short queries.Comment: Accepted to Information Retrieval Journa
Neural Architecture for Question Answering Using a Knowledge Graph and Web Corpus
In Web search, entity-seeking queries often trigger a special Question
Answering (QA) system. It may use a parser to interpret the question to a
structured query, execute that on a knowledge graph (KG), and return direct
entity responses. QA systems based on precise parsing tend to be brittle: minor
syntax variations may dramatically change the response. Moreover, KG coverage
is patchy. At the other extreme, a large corpus may provide broader coverage,
but in an unstructured, unreliable form. We present AQQUCN, a QA system that
gracefully combines KG and corpus evidence. AQQUCN accepts a broad spectrum of
query syntax, between well-formed questions to short `telegraphic' keyword
sequences. In the face of inherent query ambiguities, AQQUCN aggregates signals
from KGs and large corpora to directly rank KG entities, rather than commit to
one semantic interpretation of the query. AQQUCN models the ideal
interpretation as an unobservable or latent variable. Interpretations and
candidate entity responses are scored as pairs, by combining signals from
multiple convolutional networks that operate collectively on the query, KG and
corpus. On four public query workloads, amounting to over 8,000 queries with
diverse query syntax, we see 5--16% absolute improvement in mean average
precision (MAP), compared to the entity ranking performance of recent systems.
Our system is also competitive at entity set retrieval, almost doubling F1
scores for challenging short queries.Comment: Accepted to Information Retrieval Journa
Question Answering on Knowledge Bases and Text using Universal Schema and Memory Networks
Existing question answering methods infer answers either from a knowledge
base or from raw text. While knowledge base (KB) methods are good at answering
compositional questions, their performance is often affected by the
incompleteness of the KB. Au contraire, web text contains millions of facts
that are absent in the KB, however in an unstructured form. {\it Universal
schema} can support reasoning on the union of both structured KBs and
unstructured text by aligning them in a common embedded space. In this paper we
extend universal schema to natural language question answering, employing
\emph{memory networks} to attend to the large body of facts in the combination
of text and KB. Our models can be trained in an end-to-end fashion on
question-answer pairs. Evaluation results on \spades fill-in-the-blank question
answering dataset show that exploiting universal schema for question answering
is better than using either a KB or text alone. This model also outperforms the
current state-of-the-art by 8.5 points.\footnote{Code and data available
in \url{https://rajarshd.github.io/TextKBQA}}Comment: ACL 2017 (short
Machine Learning with World Knowledge: The Position and Survey
Machine learning has become pervasive in multiple domains, impacting a wide
variety of applications, such as knowledge discovery and data mining, natural
language processing, information retrieval, computer vision, social and health
informatics, ubiquitous computing, etc. Two essential problems of machine
learning are how to generate features and how to acquire labels for machines to
learn. Particularly, labeling large amount of data for each domain-specific
problem can be very time consuming and costly. It has become a key obstacle in
making learning protocols realistic in applications. In this paper, we will
discuss how to use the existing general-purpose world knowledge to enhance
machine learning processes, by enriching the features or reducing the labeling
work. We start from the comparison of world knowledge with domain-specific
knowledge, and then introduce three key problems in using world knowledge in
learning processes, i.e., explicit and implicit feature representation,
inference for knowledge linking and disambiguation, and learning with direct or
indirect supervision. Finally we discuss the future directions of this research
topic
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