LL(1) Parsing with Derivatives and Zippers

In this paper, we present an efficient, functional, and formally verified parsing algorithm for LL(1) context-free expressions based on the concept of derivatives of formal languages. Parsing with derivatives is an elegant parsing technique, which, in the general case, suffers from cubic worst-case time complexity and slow performance in practice. We specialise the parsing with derivatives algorithm to LL(1) context-free expressions, where alternatives can be chosen given a single token of lookahead. We formalise the notion of LL(1) expressions and show how to efficiently check the LL(1) property. Next, we present a novel linear-time parsing with derivatives algorithm for LL(1) expressions operating on a zipper-inspired data structure. We prove the algorithm correct in Coq and present an implementation as a parser combinators framework in Scala, with enumeration and pretty printing capabilities.Comment: Appeared at PLDI'20 under the title "Zippy LL(1) Parsing with Derivatives

A Typed, Algebraic Approach to Parsing

In this paper, we recall the definition of the context-free expressions (or µ-regular expressions), an algebraic presentation of the context-free languages. Then, we define a core type system for the context-free expressions which gives a compositional criterion for identifying those context-free expressions which can be parsed unambiguously by predictive algorithms in the style of recursive descent or LL(1). Next, we show how these typed grammar expressions can be used to derive a parser combinator library which both guarantees linear-time parsing with no backtracking and single-token lookahead, and which respects the natural denotational semantics of context-free expressions. Finally, we show how to exploit the type information to write a staged version of this library, which produces dramatic increases in performance, even outperforming code generated by the standard parser generator tool ocamlyacc

The political geography of religious radicalism. A compendium of selected case studies from around the globe

Religion has neither gone away nor remained irrelevant in our world today. There is no day that we do not hear news about religion in the media. The news we hear about religion and violence, however, appears to dominate the headlines. Although the history of religions and violence is not a new one, since September 11, 2001 there has been a growing concern about religious extremism and terrorism. At the same time, there is a corresponding interest in the subject of religion and violence among many disciplines. In the course GEO-83 “Political Geography of Religious Radicalism”, we offered students an excursion into the ambivalent world of religion and conflict through an exploration of different theoretical perspectives and approaches, case studies, seminal and class discussions and extensive literature review. The unique angle of interrogation that political geography offers in terms of the spatial dimensions and the power relations between different actors as well as the discursive aspects of interreligious conflicts and extremism has proved very valuable in generating insights on this subject matter. This volume is an attempt by students of the M.A. “Human Geography – Global Studies” programme of the University of Tübingen to demonstrate acquaintance with the approach of political geography to the study of religious violence and extremism. The students took on some of the most challenging conflicts and religious insurgencies confronting the world and offered insights using diverse theoretical and analytical frameworks. The analysis contained in each chapter was based on secondary data. Thus, limitations are set based on the availability of and access to data. Given the contested nature of religious conflicts and extremism, the reader is invited to consider all the articles in this volume as primarily an academic exercise with no intention to promote a certain narrative or to take sides. Knowledge is always incremental. Therefore, what is presented here is intended to increase our understanding of the phenomenon and to stimulate further research and efforts at finding solutions to the various conflicts. No doubt, this exercise has exposed the students to the rigour of scientific writing. This experience will remain invaluable to them in their continuing academic pursuit as well as in their future endeavours. The lecturers also found this experience to be highly rewarding. The process was quite daunting, but the commitment and the dedication of the students paid off

Context-Free Languages, Coalgebraically

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Promotion of dialog- spech skills of 3- to 4 year old children through dramatization games

Kvalifācijas darba temats: ir 3 – 4 gadus vecu bērnu dialogrunas sekmēšana dramatizācijas rotaļās. Pētījuma mērķis: teorētiski un praktiski izzināt 3 – 4 gadus vecu bērnu dialogrunas sekmēšanas nosacījumus. Kvalifikācijas darbu veido ievads, divas nodaļas ar apakšnodaļām, ieteikumi un secinājumi par teorētiskās literatūras analīzi un pētījuma praktisko daļu, izmantoto avotu saraksts un pielikumi. Teorētiskajā pētījumā analizētas autoru atziņas pedagoģijas un psiholoģijas teorijā. Pētīti veiksmīgi dialogrunas veidošanās nosacījumi, kā arī aplūkots dialogrunas terminu skaidrojums. Balstoties uz pedagoģijas un psiholoģijas teoriju, tika izstrādāti 3- 4 gadus vecu bērnu dialogrunas sekmēšanas kritēriji, rādītāji un līmeņi. Pētījuma teorētiskā daļa balstās uz D. Lieģenieces, I. Miltiņas, G. Svences, H. Gudjona, Ļ. Vigotska, K. Dēķena, E. Eriksona, D. Dzinteres, I. Stangaines u.c. autoru atziņām. Empīriskajām pētījumā raksturotas pētījumā izmantotās metodes un paņēmieni. Aprakstīta pētījuma vides organizēšana un dialogrunas veicināšanas saturs. Pētījumā veikta 20 bērnu dialogrunas attīstības novērošana. Empīriskajā pētījumā iegūtie dati analizēti un vizuāli attēloti tabulās un shēmās, kā arī veikta iegūto datu salīdzināšana un interpretācija. Balstoties uz pedagoģijas, psiholoģijas teoriju un empīriskajā pētījumā iegūtajiem datiem ir izstrādāti ieteikumi vecākiem, lai sekmētu 3 – 4 gadus vecu bērnu dialogrunu dramatizācijas rotaļās. Pētījuma rezultāti apstiprina hipotēzi, ka 3 – 4 gadus vecu bērnu dialogrunas veidošanās process būs sekmīgs, ja: tas notiks ciešā sadarbībā ar ģimeni; tiks nodrošināta rotaļdarbībai nepieciešamā materiālā vide; skolotāja darbība būs sistemātiska un mērķtiecīga. Kvalifikācijas darbā izmantoti 43 literatūras avoti latviešu, angļu un krievu valodā, ietverti 29 attēli, 2 tabulas un pievienoti 9 pielikumi. Kvalifikācijas darba apjoms 65 lapas. Atslēgas vārdi: runa, valoda, dialogruna, dramatizācijas rotaļas, pirmsskola, pedagoģiskais process.The subject of the qualification work is “Promotion of Dialog-speech Skills of 3 to 4 year-old Children Through Dramatization Games”. The aim of the research is to explore conditions of promoting dialog-speech skills of three to four-year-old children. The study consists of an introduction, two chapters with subdivisions, suggestions and conclusions of the analysis of theoretical literature and the practical part of the research, the list of used sources and attachments. The knowledge of authors in the theory of pedagogy and psychology have been analyzed in the theoretical research. Successful conditions for the development of the dialogue and an explanation of the terms of the dialogue have been researched. The criteria and indicators for promoting dialog-speech skills of three to four-year-old have been developed based on the theory of pedagogy and psychology. The theoretical analysis is based on thoughts of such authors as D. Lieģeniece, I. Miltiņa, G. Svence, H. Gudjona, Ļ. Vigotska, K. Dēķena, E. Eriksona, D. Dzintere, I. Stangaine and others, etc. The empirical research describes the methods used in the study. Organization of the study environment and the content of the promotion of dialog-speech skills. Dialogue-speech development observation of 20 children has been made during the research. Data collected in the empirical research are analyzed and visually displayed in tables and diagrams. The collected data have been compared and interpreted. Based on the data from pedagogy, psychology theory and empirical study, recommendations have been made for parents to promote dialog-speech skills of three to four-year-old children through dramatization games. The hypothesis has been confirmed by the results of the study – the process of dialog-speech development of three to four-year-old children will be successful if it will happen in a close cooperation with the family, the material environment requested for playing games will be ensured and the teacher’s activities will be systematic and purposeful. The qualification work is based on 43 Latvian, English and Russian language sources of literature have been used, 29 images, 2 tables and 9 attachments have been included in the study. The study work consists of 65 pages. Key words: speech, language, dialogue, dramatizing games, preschool, pedagogical process.

A Generalisation of Pre-logical Predicates to Simply Typed Formal Systems

We generalise the notion of pre-logical predicates [HS02] to arbitrary simply typed formal systems and their categorical models. We establish the basic lemma of pre-logical predicates and composability of binary pre-logical relations in this generalised setting. This generalisation takes place in a categorical framework for typed higher-order abstract syntax and semantics [Fio02,MS03]