147 research outputs found
Neural Semantic Parsing by Character-based Translation: Experiments with Abstract Meaning Representations
We evaluate the character-level translation method for neural semantic
parsing on a large corpus of sentences annotated with Abstract Meaning
Representations (AMRs). Using a sequence-to-sequence model, and some trivial
preprocessing and postprocessing of AMRs, we obtain a baseline accuracy of 53.1
(F-score on AMR-triples). We examine five different approaches to improve this
baseline result: (i) reordering AMR branches to match the word order of the
input sentence increases performance to 58.3; (ii) adding part-of-speech tags
(automatically produced) to the input shows improvement as well (57.2); (iii)
So does the introduction of super characters (conflating frequent sequences of
characters to a single character), reaching 57.4; (iv) optimizing the training
process by using pre-training and averaging a set of models increases
performance to 58.7; (v) adding silver-standard training data obtained by an
off-the-shelf parser yields the biggest improvement, resulting in an F-score of
64.0. Combining all five techniques leads to an F-score of 71.0 on holdout
data, which is state-of-the-art in AMR parsing. This is remarkable because of
the relative simplicity of the approach.Comment: Camera ready for CLIN 2017 journa
Probabilistic Bag-Of-Hyperlinks Model for Entity Linking
Many fundamental problems in natural language processing rely on determining
what entities appear in a given text. Commonly referenced as entity linking,
this step is a fundamental component of many NLP tasks such as text
understanding, automatic summarization, semantic search or machine translation.
Name ambiguity, word polysemy, context dependencies and a heavy-tailed
distribution of entities contribute to the complexity of this problem.
We here propose a probabilistic approach that makes use of an effective
graphical model to perform collective entity disambiguation. Input mentions
(i.e.,~linkable token spans) are disambiguated jointly across an entire
document by combining a document-level prior of entity co-occurrences with
local information captured from mentions and their surrounding context. The
model is based on simple sufficient statistics extracted from data, thus
relying on few parameters to be learned.
Our method does not require extensive feature engineering, nor an expensive
training procedure. We use loopy belief propagation to perform approximate
inference. The low complexity of our model makes this step sufficiently fast
for real-time usage. We demonstrate the accuracy of our approach on a wide
range of benchmark datasets, showing that it matches, and in many cases
outperforms, existing state-of-the-art methods
Wikification of learning objects using metadata as an alternative context for disambiguation
We present a methodology to wikify learning objects. Our proposal is focused on two processes: word sense disambiguation and relevant phrase selection. The disambiguation process involves the use of the learning objects metadata as either additional or alternative context. This increases the probability of success when a learning object has a low quality context. The selection of relevant phrases is perf ormed by identifying the highest values of semantic relat edness between the main subject of a learning object and t he phrases. This criterion is useful for achieving the didactic objectives of the learning object
エンティティ・リンキングのための候補検索とランキング方法に関する研究
Tohoku University乾健太郎課
Neural Collective Entity Linking
Entity Linking aims to link entity mentions in texts to knowledge bases, and
neural models have achieved recent success in this task. However, most existing
methods rely on local contexts to resolve entities independently, which may
usually fail due to the data sparsity of local information. To address this
issue, we propose a novel neural model for collective entity linking, named as
NCEL. NCEL applies Graph Convolutional Network to integrate both local
contextual features and global coherence information for entity linking. To
improve the computation efficiency, we approximately perform graph convolution
on a subgraph of adjacent entity mentions instead of those in the entire text.
We further introduce an attention scheme to improve the robustness of NCEL to
data noise and train the model on Wikipedia hyperlinks to avoid overfitting and
domain bias. In experiments, we evaluate NCEL on five publicly available
datasets to verify the linking performance as well as generalization ability.
We also conduct an extensive analysis of time complexity, the impact of key
modules, and qualitative results, which demonstrate the effectiveness and
efficiency of our proposed method.Comment: 12 pages, 3 figures, COLING201
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