A Robust Transformation-Based Learning Approach Using Ripple Down Rules for Part-of-Speech Tagging

In this paper, we propose a new approach to construct a system of transformation rules for the Part-of-Speech (POS) tagging task. Our approach is based on an incremental knowledge acquisition method where rules are stored in an exception structure and new rules are only added to correct the errors of existing rules; thus allowing systematic control of the interaction between the rules. Experimental results on 13 languages show that our approach is fast in terms of training time and tagging speed. Furthermore, our approach obtains very competitive accuracy in comparison to state-of-the-art POS and morphological taggers.Comment: Version 1: 13 pages. Version 2: Submitted to AI Communications - the European Journal on Artificial Intelligence. Version 3: Resubmitted after major revisions. Version 4: Resubmitted after minor revisions. Version 5: to appear in AI Communications (accepted for publication on 3/12/2015

Frequency vs. Association for Constraint Selection in Usage-Based Construction Grammar

A usage-based Construction Grammar (CxG) posits that slot-constraints generalize from common exemplar constructions. But what is the best model of constraint generalization? This paper evaluates competing frequency-based and association-based models across eight languages using a metric derived from the Minimum Description Length paradigm. The experiments show that association-based models produce better generalizations across all languages by a significant margin

UniBA @ KIPoS: A Hybrid Approach for Part-of-Speech Tagging

The Part of Speech tagging operation is becoming increasingly important as it represents the starting point for other high-level operations such as Speech Recognition, Machine Translation, Parsing and Information Retrieval. Although the accuracy of state-of-the-art POS-taggers reach a high level of accuracy (around 96-97%) it cannot yet be considered a solved problem because there are many variables to take into account. For example, most of these systems use lexical knowledge to assign a tag to unknown words. The task solution proposed in this work is based on a hybrid tagger, which doesn’t use any prior lexical knowledge, consisting of two different types of POS-taggers used sequentially: HMM tagger and RDRPOSTagger [(Nguyen et al., 2014), (Nguyen et al., 2016)]. We trained the hybrid model using the Development set and the combination of Development and Silver sets. The results have shown an accuracy of 0,8114 and 0,8100 respectively for the main task.L’operazione di Part of Speech tagging sta diventando sempre più importante in quanto rappresenta il punto di partenza per altre operazioni di alto livello come Speech Recognition, Machine Translation, Parsing e Information Retrieval. Sebbene l’accuratezza dei POS tagger allo stato dell’arte raggiunga un alto livello di accuratezza (intorno al 96-97%), esso non può ancora essere considerato un problema risolto perché ci sono molte variabili da tenere in considerazione. Ad esempio, la maggior parte di questi sistemi utilizza della conoscenza linguistica per assegnare un tag alle parole sconosciute. La soluzione proposta in questo lavoro si basa su un tagger ibrido, che non utilizza alcuna conoscenza linguistica pregressa, costituito da due diversi tipi di POS-tagger usati in sequenza: HMM tagger e RDRPOSTagger [(Nguyen et al., 2014), (Nguyen et al., 2016)]. Abbiamo addestrato il modello ibrido utilizzando il Development Set e la combinazione di Silver e Development Sets. I risultati hanno mostrato un’accuratezza pari a 0,8114 e 0,8100 rispettivamente per il task main

Learnability and falsifiability of Construction Grammars

The strength of Construction Grammar (CxG) is its descriptive power; its weakness is the learnability and falsifiability of its unconstrained representations. Learnability is the degree to which the optimum set of constructions can be consistently selected from the large set of potential constructions; falsifiability is the ability to make testable predictions about the constructions present in a dataset. This paper uses grammar induction to evaluate learnability and falsifiability: given a discovery-device CxG and a set of observed utterances, its learnability is its stability over sub-sets of data and its falsifiability is its ability to predict a CxG

Exposure and Emergence in Usage-Based Grammar: Computational Experiments in 35 Languages

This paper uses computational experiments to explore the role of exposure in the emergence of construction grammars. While usage-based grammars are hypothesized to depend on a learner's exposure to actual language use, the mechanisms of such exposure have only been studied in a few constructions in isolation. This paper experiments with (i) the growth rate of the constructicon, (ii) the convergence rate of grammars exposed to independent registers, and (iii) the rate at which constructions are forgotten when they have not been recently observed. These experiments show that the lexicon grows more quickly than the grammar and that the growth rate of the grammar is not dependent on the growth rate of the lexicon. At the same time, register-specific grammars converge onto more similar constructions as the amount of exposure increases. This means that the influence of specific registers becomes less important as exposure increases. Finally, the rate at which constructions are forgotten when they have not been recently observed mirrors the growth rate of the constructicon. This paper thus presents a computational model of usage-based grammar that includes both the emergence and the unentrenchment of constructions