SemEval-2017 Task 1: semantic textual similarity - multilingual and cross-lingual focused evaluation

Semantic Textual Similarity (STS) measures the meaning similarity of sentences. Applications include machine translation (MT), summarization, generation, question answering (QA), short answer grading, semantic search, dialog and conversational systems. The STS shared task is a venue for assessing the current state-of-the-art. The 2017 task focuses on multilingual and cross-lingual pairs with one sub-track exploring MT quality estimation (MTQE) data. The task obtained strong participation from 31 teams, with 17 participating in all language tracks. We summarize performance and review a selection of well performing methods. Analysis highlights common errors, providing insight into the limitations of existing models. To support ongoing work on semantic representations, the STS Benchmark is introduced as a new shared training and evaluation set carefully selected from the corpus of English STS shared task data (2012-2017)

Exploiting Background Knowledge and Inference for Scientific Relation Extraction

Tohoku University乾健太郎課

A Heuristic Based Pre-processing Methodology for Short Text Similarity Measures in Microblogs

Short text similarity measures have lots of applications in online social networks (OSN), as they are being integrated in machine learning algorithms. However, the data quality is a major challenge in most OSNs, particularly Twitter. The sparse, ambiguous, informal, and unstructured nature of the medium impose difficulties to capture the underlying semantics of the text. Therefore, text pre-processing is a crucial phase in similarity identification applications, such as clustering and classification. This is because selecting the appropriate data processing methods contributes to the increase in correlations of the similarity measure. This research proposes a novel heuristicdriven pre-processing methodology for enhancing the performance of similarity measures in the context of Twitter tweets. The components of the proposed pre-processing methodology are discussed and evaluated on an annotated dataset that was published as part of SemEval-2014 shared task. An experimental analysis was conducted using the cosine angle as a similarity measure to assess the effect of our method against a baseline (C-Method). Experimental results indicate that our approach outperforms the baseline in terms of correlations and error rates

Hizkuntza-ulermenari ekarpenak: N-gramen arteko atentzio eta lerrokatzeak antzekotasun eta inferentzia interpretagarrirako.

148 p.Hizkuntzaren Prozesamenduaren bitartez hezkuntzaren alorreko sistemaadimendunak hobetzea posible da, ikasleen eta irakasleen lan-karganabarmenki arinduz. Tesi honetan esaldi-mailako hizkuntza-ulermena aztertueta proposamen berrien bitartez sistema adimendunen hizkuntza-ulermenaareagotzen dugu, sistemei erabiltzailearen esaldiak modu zehatzagoaninterpretatzeko gaitasuna emanez. Esaldiak modu finean interpretatzekogaitasunak feedbacka modu automatikoan sortzeko aukera ematen baitu.Tesi hau garatzeko hizkuntza-ulermenean sakondu dugu antzekotasunsemantikoari eta inferentzia logikoari dagokien ezaugarriak eta sistemakaztertuz. Bereziki, esaldi barneko hitzak multzotan egituratuz eta lerrokatuzesaldiak hobeto modelatu daitezkeela erakutsi dugu. Horretarako, hitz solteaklerrokatzen dituen aurrekarien egoerako neurona-sare sistema batinplementatu eta n-grama arbitrarioak lerrokatzeko moldaketak egin ditugu.Hitzen arteko lerrokatzea aspalditik ezaguna bada ere, tesi honek, lehen aldiz,n-grama arbitrarioak atentzio-mekanismo baten bitartez lerrokatzekoproposamenak plazaratzen ditu.Gainera, esaldien arteko antzekotasunak eta desberdintasunak moduzehatzean identifikatzeko, esaldien interpretagarritasuna areagotzeko etaikasleei feedback zehatza emateko geruza berri bat sortu dugu: iSTS.Antzekotasun semantikoa eta inferentzia logikoa biltzen dituen geruzahorrekin chunkak lerrokatu ditugu, eta ikasleei feedback zehatza emateko gaiizan garela frogatu dugu hezkuntzaren testuinguruko bi ebaluazioeszenariotan.Tesi honekin batera hainbat sistema eta datu-multzo argitaratu diraetorkizunean komunitate zientifikoak ikertzen jarrai dezan

Deep learning based semantic textual similarity for applications in translation technology

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy.Semantic Textual Similarity (STS) measures the equivalence of meanings between two textual segments. It is a fundamental task for many natural language processing applications. In this study, we focus on employing STS in the context of translation technology. We start by developing models to estimate STS. We propose a new unsupervised vector aggregation-based STS method which relies on contextual word embeddings. We also propose a novel Siamese neural network based on efficient recurrent neural network units. We empirically evaluate various unsupervised and supervised STS methods, including these newly proposed methods in three different English STS datasets, two non- English datasets and a bio-medical STS dataset to list the best supervised and unsupervised STS methods. We then embed these STS methods in translation technology applications. Firstly we experiment with Translation Memory (TM) systems. We propose a novel TM matching and retrieval method based on STS methods that outperform current TM systems. We then utilise the developed STS architectures in translation Quality Estimation (QE). We show that the proposed methods are simple but outperform complex QE architectures and improve the state-of-theart results. The implementations of these methods have been released as open source

Gaussian Processes for Text Regression

Text Regression is the task of modelling and predicting numerical indicators or response variables from textual data. It arises in a range of different problems, from sentiment and emotion analysis to text-based forecasting. Most models in the literature apply simple text representations such as bag-of-words and predict response variables in the form of point estimates. These simplifying assumptions ignore important information coming from the data such as the underlying uncertainty present in the outputs and the linguistic structure in the textual inputs. The former is particularly important when the response variables come from human annotations while the latter can capture linguistic phenomena that go beyond simple lexical properties of a text. In this thesis our aim is to advance the state-of-the-art in Text Regression by improving these two aspects, better uncertainty modelling in the response variables and improved text representations. Our main workhorse to achieve these goals is Gaussian Processes (GPs), a Bayesian kernelised probabilistic framework. GP-based regression models the response variables as well-calibrated probability distributions, providing additional information in predictions which in turn can improve subsequent decision making. They also model the data using kernels, enabling richer representations based on similarity measures between texts. To be able to reach our main goals we propose new kernels for text which aim at capturing richer linguistic information. These kernels are then parameterised and learned from the data using efficient model selection procedures that are enabled by the GP framework. Finally we also capitalise on recent advances in the GP literature to better capture uncertainty in the response variables, such as multi-task learning and models that can incorporate non-Gaussian variables through the use of warping functions. Our proposed architectures are benchmarked in two Text Regression applications: Emotion Analysis and Machine Translation Quality Estimation. Overall we are able to obtain better results compared to baselines while also providing uncertainty estimates for predictions in the form of posterior distributions. Furthermore we show how these models can be probed to obtain insights about the relation between the data and the response variables and also how to apply predictive distributions in subsequent decision making procedures

Textual entailment from image caption denotations

Understanding the meaning of linguistic expressions is a fundamental task of natural language processing. While distributed representations have become a powerful technique for modeling lexical semantics, but they have traditionally relied on ungrounded text corpora to identify semantically similar words. In contrast, this thesis explicitly models the denotation of linguistic expressions by building representations from grounded image captions. This allows us to use descriptions of the world to learn connections that would be difficult to identify in text-based corpora. In particular, we explore novel approaches to entailment that capture everyday world knowledge missing from other NLP tasks, on both existing datasets and our own new dataset. We also present a novel embedding model that produces phrase representations that are informed by our grounded representation. We conclude with an analysis of how grounded embeddings differ from standard distributional embeddings and suggestions for future refinement of this approach