Filip Klubička


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English WordNet Random Walk Pseudo-Corpora
Filip Klubička | Alfredo Maldonado | Abhijit Mahalunkar | John Kelleher
Proceedings of the 12th Language Resources and Evaluation Conference

This is a resource description paper that describes the creation and properties of a set of pseudo-corpora generated artificially from a random walk over the English WordNet taxonomy. Our WordNet taxonomic random walk implementation allows the exploration of different random walk hyperparameters and the generation of a variety of different pseudo-corpora. We find that different combinations of parameters result in varying statistical properties of the generated pseudo-corpora. We have published a total of 81 pseudo-corpora that we have used in our previous research, but have not exhausted all possible combinations of hyperparameters, which is why we have also published a codebase that allows the generation of additional WordNet taxonomic pseudo-corpora as needed. Ultimately, such pseudo-corpora can be used to train taxonomic word embeddings, as a way of transferring taxonomic knowledge into a word embedding space.


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Synthetic, yet natural: Properties of WordNet random walk corpora and the impact of rare words on embedding performance
Filip Klubička | Alfredo Maldonado | Abhijit Mahalunkar | John Kelleher
Proceedings of the 10th Global Wordnet Conference

Creating word embeddings that reflect semantic relationships encoded in lexical knowledge resources is an open challenge. One approach is to use a random walk over a knowledge graph to generate a pseudo-corpus and use this corpus to train embeddings. However, the effect of the shape of the knowledge graph on the generated pseudo-corpora, and on the resulting word embeddings, has not been studied. To explore this, we use English WordNet, constrained to the taxonomic (tree-like) portion of the graph, as a case study. We investigate the properties of the generated pseudo-corpora, and their impact on the resulting embeddings. We find that the distributions in the psuedo-corpora exhibit properties found in natural corpora, such as Zipf’s and Heaps’ law, and also observe that the proportion of rare words in a pseudo-corpus affects the performance of its embeddings on word similarity.


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Is it worth it? Budget-related evaluation metrics for model selection
Filip Klubička | Giancarlo D. Salton | John D. Kelleher
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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ADAPT at SemEval-2018 Task 9: Skip-Gram Word Embeddings for Unsupervised Hypernym Discovery in Specialised Corpora
Alfredo Maldonado | Filip Klubička
Proceedings of The 12th International Workshop on Semantic Evaluation

This paper describes a simple but competitive unsupervised system for hypernym discovery. The system uses skip-gram word embeddings with negative sampling, trained on specialised corpora. Candidate hypernyms for an input word are predicted based based on cosine similarity scores. Two sets of word embedding models were trained separately on two specialised corpora: a medical corpus and a music industry corpus. Our system scored highest in the medical domain among the competing unsupervised systems but performed poorly on the music industry domain. Our system does not depend on any external data other than raw specialised corpora.


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Producing Monolingual and Parallel Web Corpora at the Same Time - SpiderLing and Bitextor’s Love Affair
Nikola Ljubešić | Miquel Esplà-Gomis | Antonio Toral | Sergio Ortiz Rojas | Filip Klubička
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

This paper presents an approach for building large monolingual corpora and, at the same time, extracting parallel data by crawling the top-level domain of a given language of interest. For gathering linguistically relevant data from top-level domains we use the SpiderLing crawler, modified to crawl data written in multiple languages. The output of this process is then fed to Bitextor, a tool for harvesting parallel data from a collection of documents. We call the system combining these two tools Spidextor, a blend of the names of its two crucial parts. We evaluate the described approach intrinsically by measuring the accuracy of the extracted bitexts from the Croatian top-level domain “.hr” and the Slovene top-level domain “.si”, and extrinsically on the English-Croatian language pair by comparing an SMT system built from the crawled data with third-party systems. We finally present parallel datasets collected with our approach for the English-Croatian, English-Finnish, English-Serbian and English-Slovene language pairs.

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New Inflectional Lexicons and Training Corpora for Improved Morphosyntactic Annotation of Croatian and Serbian
Nikola Ljubešić | Filip Klubička | Željko Agić | Ivo-Pavao Jazbec
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

In this paper we present newly developed inflectional lexcions and manually annotated corpora of Croatian and Serbian. We introduce hrLex and srLex - two freely available inflectional lexicons of Croatian and Serbian - and describe the process of building these lexicons, supported by supervised machine learning techniques for lemma and paradigm prediction. Furthermore, we introduce hr500k, a manually annotated corpus of Croatian, 500 thousand tokens in size. We showcase the three newly developed resources on the task of morphosyntactic annotation of both languages by using a recently developed CRF tagger. We achieve best results yet reported on the task for both languages, beating the HunPos baseline trained on the same datasets by a wide margin.

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Dealing with Data Sparseness in SMT with Factured Models and Morphological Expansion: a Case Study on Croatian
Victor M. Sánchez-Cartagena | Nikola Ljubešić | Filip Klubička
Proceedings of the 19th Annual Conference of the European Association for Machine Translation

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Collaborative Development of a Rule-Based Machine Translator between Croatian and Serbian
Filip Klubička | Gema Ramírez-Sánchez | Nikola Ljubešić
Proceedings of the 19th Annual Conference of the European Association for Machine Translation

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Language Related Issues for Machine Translation between Closely Related South Slavic Languages
Maja Popović | Mihael Arčan | Filip Klubička
Proceedings of the Third Workshop on NLP for Similar Languages, Varieties and Dialects (VarDial3)

Machine translation between closely related languages is less challenging and exibits a smaller number of translation errors than translation between distant languages, but there are still obstacles which should be addressed in order to improve such systems. This work explores the obstacles for machine translation systems between closely related South Slavic languages, namely Croatian, Serbian and Slovenian. Statistical systems for all language pairs and translation directions are trained using parallel texts from different domains, however mainly on spoken language i.e. subtitles. For translation between Serbian and Croatian, a rule-based system is also explored. It is shown that for all language pairs and translation systems, the main obstacles are differences between structural properties.


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Predicting Inflectional Paradigms and Lemmata of Unknown Words for Semi-automatic Expansion of Morphological Lexicons
Nikola Ljubešić | Miquel Esplà-Gomis | Filip Klubička | Nives Mikelić Preradović
Proceedings of the International Conference Recent Advances in Natural Language Processing


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{bs,hr,sr}WaC - Web Corpora of Bosnian, Croatian and Serbian
Nikola Ljubešić | Filip Klubička
Proceedings of the 9th Web as Corpus Workshop (WaC-9)

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Comparing two acquisition systems for automatically building an English—Croatian parallel corpus from multilingual websites
Miquel Esplà-Gomis | Filip Klubička | Nikola Ljubešić | Sergio Ortiz-Rojas | Vassilis Papavassiliou | Prokopis Prokopidis
Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14)

In this paper we compare two tools for automatically harvesting bitexts from multilingual websites: bitextor and ILSP-FC. We used both tools for crawling 21 multilingual websites from the tourism domain to build a domain-specific English―Croatian parallel corpus. Different settings were tried for both tools and 10,662 unique document pairs were obtained. A sample of about 10% of them was manually examined and the success rate was computed on the collection of pairs of documents detected by each setting. We compare the performance of the settings and the amount of different corpora detected by each setting. In addition, we describe the resource obtained, both by the settings and through the human evaluation, which has been released as a high-quality parallel corpus.