18 research outputs found
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Neural Sequence-Labelling Models for Grammatical Error Correction
We propose an approach to N-best list reranking
using neural sequence-labelling
models. We train a compositional model
for error detection that calculates the probability
of each token in a sentence being
correct or incorrect, utilising the full sentence
as context. Using the error detection
model, we then re-rank the N best
hypotheses generated by statistical machine
translation systems. Our approach
achieves state-of-the-art results on error
correction for three different datasets, and
it has the additional advantage of only using
a small set of easily computed features
that require no linguistic input
Correcting Preposition Errors in Learner English Using Error Case Frames and Feedback Messages
Abstract This paper presents a novel framework called error case frames for correcting preposition errors. They are case frames specially designed for describing and correcting preposition errors. Their most distinct advantage is that they can correct errors with feedback messages explaining why the preposition is erroneous. This paper proposes a method for automatically generating them by comparing learner and native corpora. Experiments show (i) automatically generated error case frames achieve a performance comparable to conventional methods; (ii) error case frames are intuitively interpretable and manually modifiable to improve them; (iii) feedback messages provided by error case frames are effective in language learning assistance. Considering these advantages and the fact that it has been difficult to provide feedback messages by automatically generated rules, error case frames will likely be one of the major approaches for preposition error correction
Grammatical error correction using hybrid systems and type filtering
This paper describes our submission to the CoNLL 2014 shared task on grammatical error correction using a hybrid approach, which includes both a rule-based and an SMT system augmented by a large webbased
language model. Furthermore, we demonstrate that correction type estimation can be used to remove unnecessary corrections, improving precision without harming recall. Our best hybrid system achieves state of-the-art results, ranking first on the original test set and second on the test set with alternative annotations.[We would like to thank] Cambridge English Language Assessment, a division of Cambridge Assessment, for supporting this research
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Automatic annotation of error types for grammatical error correction
Grammatical Error Correction (GEC) is the task of automatically detecting and correcting
grammatical errors in text. Although previous work has focused on developing systems that
target specific error types, the current state of the art uses machine translation to correct all error
types simultaneously. A significant disadvantage of this approach is that machine translation
does not produce annotated output and so error type information is lost. This means we can only
evaluate a system in terms of overall performance and cannot carry out a more detailed analysis
of different aspects of system performance.
In this thesis, I develop a system to automatically annotate parallel original and corrected
sentence pairs with explicit edits and error types. In particular, I first extend the Damerau-
Levenshtein alignment algorithm to make use of linguistic information when aligning parallel
sentences, and supplement this alignment with a set of merging rules to handle multi-token
edits. The output from this algorithm surpasses other edit extraction approaches in terms of
approximating human edit annotations and is the current state of the art. Having extracted the
edits, I next classify them according to a new rule-based error type framework that depends only
on automatically obtained linguistic properties of the data, such as part-of-speech tags. This
framework was inspired by existing frameworks, and human judges rated the appropriateness
of the predicted error types as ‘Good’ (85%) or ‘Acceptable’ (10%) in a random sample of 200
edits. The whole system is called the ERRor ANnotation Toolkit (ERRANT) and is the first
toolkit capable of automatically annotating parallel sentences with error types.
I demonstrate the value of ERRANT by applying it to the system output produced by the participants of the CoNLL-2014 shared task, and carry out a detailed error type analysis of
system performance for the first time. I also develop a simple language model based approach
to GEC, that does not require annotated training data, and show how it can be improved using
ERRANT error types
Grammatical Error Correction: A Survey of the State of the Art
Grammatical Error Correction (GEC) is the task of automatically detecting and
correcting errors in text. The task not only includes the correction of
grammatical errors, such as missing prepositions and mismatched subject-verb
agreement, but also orthographic and semantic errors, such as misspellings and
word choice errors respectively. The field has seen significant progress in the
last decade, motivated in part by a series of five shared tasks, which drove
the development of rule-based methods, statistical classifiers, statistical
machine translation, and finally neural machine translation systems which
represent the current dominant state of the art. In this survey paper, we
condense the field into a single article and first outline some of the
linguistic challenges of the task, introduce the most popular datasets that are
available to researchers (for both English and other languages), and summarise
the various methods and techniques that have been developed with a particular
focus on artificial error generation. We next describe the many different
approaches to evaluation as well as concerns surrounding metric reliability,
especially in relation to subjective human judgements, before concluding with
an overview of recent progress and suggestions for future work and remaining
challenges. We hope that this survey will serve as comprehensive resource for
researchers who are new to the field or who want to be kept apprised of recent
developments
Robust Text Correction for Grammar and Fluency
Grammar is one of the most important properties of natural language. It is a set of structural (i.e., syntactic and morphological) rules that are shared among native speakers in order to engage smooth communication. Automated grammatical error correction (GEC) is a natural language processing (NLP) application, which aims to correct grammatical errors in a given source sentence by computational models.
Since the data-driven statistical methods began in 1990s and early 2000s, the GEC com- munity has worked on establishing a common framework for its evaluation (i.e., dataset and metric for benchmarking) in order to compare GEC models’ performance quantitatively. A series of shared tasks since early 2010s is a good example of this.
In the first half of this thesis, I propose character-level and token-level error correction algorithms. For the character-level error correction, I introduce a semi-character recurrent neural network, which is motivated by a finding in psycholinguistics, called the Cmabrigde Uinervtisy (Cambridge University) effect or typoglycemia. For word-level error correc- tion, I propose an error-repair dependency parsing algorithm for ungrammatical texts. The algorithm can parse sentences and correct grammatical errors simultaneously.
However, it is important to note that grammatical errors are not usually limited to mor- phological or syntactic errors. For example, collocational errors such as *quick/fast food and *fast/quick meal are not fully explained by only syntactic rules. This is another im- portant property of natural language, called fluency (or acceptability). Fluency is a level of mastery that goes beyond knowledge of how to follow the rules, and includes know- ing when they can be broken or flouted. In fact, the GEC community has also extended the scope of error types from closed class errors (e.g., noun numbers, verb forms) to the fluency-oriented errors.
The second half of this thesis investigates GEC while considering fluency as well as grammaticality. When it comes to “whole-sentence” correction, by extending the scope of errors considering fluency as well as grammaticality, the GEC community has overlooked the reliability and validity of the task scheme (i.e., evaluation metric and dataset for bench- marking). Thus, I reassess the goals of GEC as a “whole-sentence” rewriting task while considering fluency. Following the fluency-oriented GEC framework, I introduce a new benchmark corpus that is more diverse in various aspects such as proficiency, topics, and learners’ native languages.
Based on the fluency-oriented metric and dataset, I propose a new “whole-sentence” error correction model with neural reinforcement learning. Unlike conventional maximum likelihood estimation (MLE), the model directly optimizes toward an objective that consid- ers a sentence-level, task-specific evaluation metric. I demonstrate that the proposed model outperforms MLE in human and automated evaluation metrics.
Finally, I conclude the thesis and outline ideas and suggestions for future GEC research