UNIMIB@NEEL-IT: Named Entity Recognition and Linking of Italian Tweets

Questo articolo descrive il sistema proposto dal gruppo UNIMIB per il task di Named Entity Recognition and Linking applicato a tweet in lingua italiana (NEEL-IT). Il sistema, che rappresenta un approccio iniziale al problema, \ue8 costituito da tre passaggi fondamentali: (1) Named Entity Recognition tramite l\u2019utilizzo di Conditional Random Fields, (2) Named Entity Linking considerando sia approcci supervisionati sia modelli di linguaggio basati su reti neurali, e (3) NIL clustering tramite un approccio basato su grafi.This paper describes the framework proposed by the UNIMIB Team for the task of Named Entity Recognition and Linking of Italian Tweets (NEEL-IT). The proposed pipeline, which represents an entry level system, is composed of three main steps: (1) Named Entity Recognition using Conditional Random Fields, (2) Named Entity Linking by considering both Supervised and Neural-Network Language models, and (3) NIL clustering byusing a graph-based approach

Speaker-independent emotion recognition exploiting a psychologically-inspired binary cascade classification schema

In this paper, a psychologically-inspired binary cascade classification schema is proposed for speech emotion recognition. Performance is enhanced because commonly confused pairs of emotions are distinguishable from one another. Extracted features are related to statistics of pitch, formants, and energy contours, as well as spectrum, cepstrum, perceptual and temporal features, autocorrelation, MPEG-7 descriptors, Fujisakis model parameters, voice quality, jitter, and shimmer. Selected features are fed as input to K nearest neighborhood classifier and to support vector machines. Two kernels are tested for the latter: Linear and Gaussian radial basis function. The recently proposed speaker-independent experimental protocol is tested on the Berlin emotional speech database for each gender separately. The best emotion recognition accuracy, achieved by support vector machines with linear kernel, equals 87.7%, outperforming state-of-the-art approaches. Statistical analysis is first carried out with respect to the classifiers error rates and then to evaluate the information expressed by the classifiers confusion matrices. © Springer Science+Business Media, LLC 2011

EVALITA Evaluation of NLP and Speech Tools for Italian - December 17th, 2020

Welcome to EVALITA 2020! EVALITA is the evaluation campaign of Natural Language Processing and Speech Tools for Italian. EVALITA is an initiative of the Italian Association for Computational Linguistics (AILC, http://www.ai-lc.it) and it is endorsed by the Italian Association for Artificial Intelligence (AIxIA, http://www.aixia.it) and the Italian Association for Speech Sciences (AISV, http://www.aisv.it)

Word Sense Discrimination: A Gangplank Algorithm

L\u2019obiettivo di questo articolo \ue8 descrivere un approccio di clustering non supervisionato e basato su grafi per individuare e discriminare i differenti sensi che un termine pu\uf2 assumere all\u2019interno di un testo. Partendo da un grafo di cooccorrenze, vi definiamo una distanza fra nodi e applichiamo un algoritmo basato sulle \u201cpasserelle\u201d, cio\ue8 archi che separano regioni dense (\u201cisole\u201d) all\u2019interno del grafo. Discutiamo i risultati ottenuti su un insieme di dati composto da tweet.In this paper we present an unsupervised, graph-based approach for Word Sense Discrimination. Given a set of text sentences, a word co-occurrence graph is derived and a distance based on Jaccard index is defined on it; subsequently, the new distance is used to cluster the neighbour nodes of ambiguous terms using the concept of \u201cgangplanks\u201d as edges that separate denser regions (\u201cislands\u201d) in the graph. The proposed approach has been evaluated on a real data set, showing promising performance in Word Sense Discrimination

Relational Bayesian Model Averaging for Sentiment Analysis in Social Networks

Nowadays, the exponential diffusion of information forces Machine Learning algorithms to take relations into account in addition to data, which are no longer independent. We propose a Bayesian ensemble learning methodology named Relational Bayesian Model Averaging (RBMA) which, in addition to a probabilistic ensemble voting, takes relations into account. We tested the RBMA on a benchmark dataset for Sentiment Analysis in social networks and we compared it with its previous non-relational variant and we show that the introduction of relations significantly improves the performance of classification. Moreover, we propose a model for making predictions when new data becomes available modifying and increasing the underneath graph of relations on which the RBMA was trained

Word sense discrimination on tweets: A graph-based approach

In this paper we are going to detail an unsupervised, graph-based approach for word sense discrimination on tweets. We deal with this problem by constructing a word graph of co-occurrences. By defining a distance on this graph, we obtain a word metric space, on which we can apply an aggregative algorithm for word clustering. As a result, we will get word clusters representing contexts that discriminate the possible senses of a term. We present some experimental results both on a data set consisting of tweets we collected and on the data set of task 14 at SemEval-2010

Ensemble learning on visual and textual data for social image emotion classification

Texts, images and other information are posted everyday on the social network and provides a large amount of multimodal data. The aim of this work is to investigate if combining and integrating both visual and textual data permits to identify emotions elicited by an image. We focus on image emotion classification within eight emotion categories: amusement, awe, contentment, excitement, anger, disgust, fear and sadness. Within this classification task we here propose to adopt ensemble learning approaches based on the Bayesian model averaging method, that combine five state-of-the-art classifiers. The proposed ensemble approaches consider predictions given by several classification models, based on visual and textual data, through respectively a late and an early fusion schemes. Our investigations show that an ensemble method based on a late fusion of unimodal classifiers permits to achieve high classification performance within all of the eight emotion classes. The improvement is higher when deep image representations are adopted as visual features, compared with hand-crafted ones

Computers & operations research

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