Developments from enquiries into the learnability of the pattern languages from positive data

AbstractThe pattern languages are languages that are generated from patterns, and were first proposed by Angluin as a non-trivial class that is inferable from positive data [D. Angluin, Finding patterns common to a set of strings, Journal of Computer and System Sciences 21 (1980) 46–62; D. Angluin, Inductive inference of formal languages from positive data, Information and Control 45 (1980) 117–135]. In this paper we chronologize some results that developed from the investigations on the inferability of the pattern languages from positive data

Bad news on decision problems for patterns

We study the inclusion problem for pattern languages, which is shown to be undecidable by Jiang et al. (J. Comput. System Sci. 50, 1995). More precisely, Jiang et al. demonstrate that there is no effective procedure deciding the inclusion for the class of all pattern languages over all alphabets. Most applications of pattern languages, however, consider classes over fixed alphabets, and therefore it is practically more relevant to ask for the existence of alphabet-specific decision procedures. Our first main result states that, for all but very particular cases, this version of the inclusion problem is also undecidable. The second main part of our paper disproves the prevalent conjecture on the inclusion of so-called similar E-pattern languages, and it explains the devastating consequences of this result for the intensive previous research on the most prominent open decision problem for pattern languages, namely the equivalence problem for general E-pattern languages

Developing arabic usability guidelines for e-learning websites in higher education

Despite the widespread availability of e-learning websites in the Arab world, the link between Arabic culture, Arabic language and the usability of e-learning websites has been researched very little. Moreover, the Arab world lacks usability guidelines to support the creation of effective Arabic e-learning websites. Poor usability often means poor user interaction and hence reduced user acceptance and satisfaction.This research undertakes an experiment with 50 Arab participants to investigate their judgement of an Arabic and English e-learning website. The participants completed seven e-learning tasks and completed an e-learning, evaluation, usability, and aesthetics questionnaire. The participants gave their feedback on the positive and negative features of each e-learning website following the experiment. This experiment was followed by a case study and fuzzy set theory analysis to validate the results. The findings are summarised in nine Arabic usability guidelines. This thesis contributes to the body of knowledge in various ways. Firstly, it establishes the differences between Arabic and English languages and their effects on usability. Secondly, it identifies the design elements and barriers that affect the usability of Arabic websites. Thirdly, it produces nine usability guidelines for improving the usability of Arabic e-learning websites. In particular, these guidelines suggest using appropriate images and contents, which respect cultural and religious values, by using blue as a main colour, 12/13-point font size and Arabic Traditional font type, and that the written content should be written by an native Arabic-speaking writer. These guidelines contribute towards creating e-learning systems that have high learnability and high efficiency. However, aesthetics may not have a strong influence on the judgement of Arab users

The Typological Diversity of Morphomes: A Cross-Linguistic Study of Unnatural Morphology

This is the first typologically-oriented book-length treatment of morphomes, systematic morphological identities, usually within inflectional paradigms, that do not map onto syntactic or semantic natural classes. In the first half of the book, Borja Herce outlines the theoretical and empirical challenges associated with the identification and definition of morphomes, and surveys their links with related notions such as syncretism, homophony, segmentation, and economy, among others. He also presents the different ways in which morphomic structures in a language have been observed to emerge, change, and disappear. The second part of the book contains its core contribution: a database of 120 morphomes across 79 languages from a range of families, which are presented and analysed in detail. A range of findings emerge as a result, including the idiosyncratic nature of morphomes in the Romance languages, the existence of cross-linguistically recurrent unnatural patterns, and the preference for more natural structures even among morphomes. The database also allows further explorations of other issues such as the effect of learnability and communicative efficiency on morphological structures, and the lexical and grammatical informativity of morphs and their distribution