Improvements to Korektor: A Case Study with Native and Non-Native Czech

Abstract: We present recent developments of Korektor, a statistical spell checking system. In addition to lexicon, Korektor uses language models to find real-word errors, detectable only in context. The models and error probabilities, learned from error corpora, are also used to suggest the most likely corrections. Korektor was originally trained on a small error corpus and used language models extracted from an in-house corpus WebColl. We show two recent improvements: • We built new language models from freely available (shuffled) versions of the Czech National Corpus and show that these perform consistently better on texts produced both by native speakers and nonnative learners of Czech. • We trained new error models on a manually annotated learner corpus and show that they perform better than the standard error model (in error detection) not only for the learners' texts, but also for our standard evaluation data of native Czech. For error correction, the standard error model outperformed non-native models in 2 out of 3 test datasets. We discuss reasons for this not-quite-intuitive improvement. Based on these findings and on an analysis of errors in both native and learners' Czech, we propose directions for further improvements of Korektor

Compiling and annotating a learner corpus for a morphologically rich language: CzeSL, a corpus of non-native Czech

Learner corpora, linguistic collections documenting a language as used by learners, provide an important empirical foundation for language acquisition research and teaching practice. This book presents CzeSL, a corpus of non-native Czech, against the background of theoretical and practical issues in the current learner corpus research. Languages with rich morphology and relatively free word order, including Czech, are particularly challenging for the analysis of learner language. The authors address both the complexity of learner error annotation, describing three complementary annotation schemes, and the complexity of description of non-native Czech in terms of standard linguistic categories. The book discusses in detail practical aspects of the corpus creation: the process of collection and annotation itself, the supporting tools, the resulting data, their formats and search platforms. The chapter on use cases exemplifies the usefulness of learner corpora for teaching, language acquisition research, and computational linguistics. Any researcher developing learner corpora will surely appreciate the concluding chapter listing lessons learned and pitfalls to avoid

Grammar and Corpora 2016

In recent years, the availability of large annotated corpora, together with a new interest in the empirical foundation and validation of linguistic theory and description, has sparked a surge of novel work using corpus methods to study the grammar of natural languages. This volume presents recent developments and advances, firstly, in corpus-oriented grammar research with a special focus on Germanic, Slavic, and Romance languages and, secondly, in corpus linguistic methodology as well as the application of corpus methods to grammar-related fields. The volume results from the sixth international conference Grammar and Corpora (GaC 2016), which took place at the Institute for the German Language (IDS) in Mannheim, Germany, in November 2016.Die Verfügbarkeit großer annotierter und durchsuchbarer Korpora, verbunden mit einem neuerwachten Interesse an der empirischen Grundlegung und Validierung linguistischer Theorie und Beschreibung hat in letzter Zeit zu einer regelrechten Welle interessanter Arbeiten zur Grammatik natürlicher Sprachen geführt. Dieser Band präsentiert zum einen neuere Entwicklungen in der korpusorientierten Forschung zur Grammatik germanischer, romanischer und slawischer Sprachen und zum anderen innovative Ansätze in der einschlägigen korpuslinguistischen Methodologie, die auch Anwendung im Umfeld der Grammatik finden. Der Band fasst die Beiträge der sechsten internationalen Konferenz Grammar and Corpora zusammen, die im November 2016 am Institut für Deutsche Sprache (IDS) in Mannheim stattfand