We prove a kind of a pumping lemma for languages accepted by one-register alternating finite-memory automata. As a corollary, we obtain that the set of lengths of words in such languages is semi-linear.
Yudai Tanabe, Luthfan Anshar Lubis, Tomoyuki Aotani
et al.
Programming with versions is a paradigm that allows a program to use multiple versions of a module so that the programmer can selectively use functions from both older and newer versions of a single module. Previous work formalized $λ_{\mathrm{VL}}$, a core calculus for programming with versions, but it has not been integrated into practical programming languages. In this paper, we propose VL, a Haskell-subset surface language for $λ_{\mathrm{VL}}$ along with its compilation method. We formally describe the core part of the VL compiler, which translates from the surface language to the core language by leveraging Girard's translation, soundly infers the consistent version of expressions along with their types, and generates a multi-version interface by bundling specific-version interfaces. We conduct a case study to show how VL supports practical software evolution scenarios and discuss the method's scalability.
Jonas Schmidt, Thomas Schwentick, Jennifer Todtenhoefer
Previous work on Dynamic Complexity has established that there exist dynamic constant-time parallel algorithms for regular tree languages and context-free languages under label or symbol changes. However, these algorithms were not developed with the goal to minimise work (or, equivalently, the number of processors). In fact, their inspection yields the work bounds $O(n^2)$ and $O(n^7)$ per change operation, respectively. In this paper, dynamic algorithms for regular tree languages are proposed that generalise the previous algorithms in that they allow unbounded node rank and leaf insertions, while improving the work bound from $O(n^2)$ to $O(n^ε)$, for arbitrary $ε> 0$. For context-free languages, algorithms with better work bounds (compared with $O(n^7)$) for restricted classes are proposed: for every $ε> 0$ there are such algorithms for deterministic context-free languages with work bound $O(n^{3+ε})$ and for visibly pushdown languages with work bound $O(n^{2+ε})$.
Effectful programs interact in ways that go beyond simple input-output, making compositional reasoning challenging. Existing work has shown that when such programs are ``separate'', i.e., when programs do not interfere with each other, it can be easier to reason about them. While reasoning about separated resources has been well-studied, there has been little work on reasoning about separated effects, especially for functional, higher-order programming languages. We propose two higher-order languages that can reason about sharing and separation in effectful programs. Our first language $λ_{\text{INI}}$ has a linear type system and probabilistic semantics, where the two product types capture independent and possibly-dependent pairs. Our second language $λ_{\text{INI}}^2$ is two-level, stratified language, inspired by Benton's linear-non-linear (LNL) calculus. We motivate this language with a probabilistic model, but we also provide a general categorical semantics and exhibit a range of concrete models beyond probabilistic programming. We prove soundness theorems for all of our languages; our general soundness theorem for our categorical models of $λ_{\text{INI}}^2$ uses a categorical gluing construction.
Pumping lemmata are the main tool to prove that a certain language does not belong to a class of languages like the recognizable languages or the context-free languages. Essentially two pumping lemmata exist for the recognizable weighted languages: the classical one for the Boolean semiring (i.e., the unweighted case), which can be generalized to zero-sum free semirings, and the one for fields. A joint generalization of these two pumping lemmata is provided that applies to all Artinian semirings, over which all finitely generated semimodules have a finite bound on the length of chains of strictly increasing subsemimodules. Since Artinian rings are exactly those that satisfy the Descending Chain Condition, the Artinian semirings include all fields and naturally also all finite semirings (like the Boolean semiring). The new pumping lemma thus covers most previously known pumping lemmata for recognizable weighted languages.
COOL is an Object-Oriented programming language used to teach compiler design in many undergraduate and graduate courses. Because most students are unfamiliar with the language and code editors and IDEs often lack the support for COOL, writing code and test programs in COOL are a burden to students, causing them to not fully understand many important and advanced features of the language and compiler. In this tool paper, we describe COOLIO,an extension to support COOL in the popular VSCode IDE. COOLIOprovides (i) syntax highlighting supports for the COOL language through lexing and parsing, (ii) semantics-aware autocompletion features that help students write less code and reduce the burden of having to remember unfamiliar COOL grammar and syntax, and (iii) relevant feedback from the underlying COOL interpreter/compiler (e.g., error messages, typing information) to the students through VSCode editor to aid debugging. We believe that COOLIO will help students enjoy writing COOL programs and consequently learn and appreciate more advanced compiler concepts.
We present Quickstrom, a property-based testing system for acceptance testing of interactive applications. Using Quickstrom, programmers can specify the behaviour of web applications as properties in our testing-oriented dialect of Linear Temporal Logic (LTL) called QuickLTL, and then automatically test their application against the given specification with hundreds of automatically generated interactions. QuickLTL extends existing finite variants of LTL for the testing use-case, determining likely outcomes from partial traces whose minimum length is itself determined by the LTL formula. This temporal logic is embedded in our specification language, Specstrom, which is designed to be approachable to web programmers, expressive for writing specifications, and easy to analyse. Because Quickstrom tests only user-facing behaviour, it is agnostic to the implementation language of the system under test. We therefore formally specify and test many implementations of the popular TodoMVC benchmark, used for evaluation and comparison across various web frontend frameworks and languages. Our tests uncovered bugs in almost half of the available implementations.
Kaja Borthen, Åshild Søfteland, Perlaug Marie Kveen
et al.
Denne artikkelen rapporterer om ein studie av geografiske og demografiske trekk ved 46 etterstilte uttrykk i norske talemål, mellom anna gitt, sant og kan du skjønne. I fyrste del av studien er spørjeskjema nytta som metode. Resultata frå denne undersøkinga viser i kva grad informantar frå ulike stader i Noreg rapporterer om bruk av dei etterstilte uttrykka. Andre del av studien er ei undersøking av førekomstar av etterstilte uttrykk i korpusa Nordisk dialektkorpus og LIA norsk. Samla viser studien at i) mange av dei 46 etterstilte uttrykka er avgrensa geografisk, ii) ein del av uttrykka blir nytta i større grad av dei eldre informantane enn av dei yngre, og omvendt, iii) nokre få uttrykk har ein meir frekvent bruk hos menn enn hos kvinner, og omvendt, og iv) yngre språkbrukarar ser ut til å plassere uttrykk i den etterstilte posisjonen meir hyppig enn eldre når fleire posisjonar er mogleg. I tillegg gjev undersøkinga auka innsikt om dei to metodane som vart nytta.
Philology. Linguistics, Germanic languages. Scandinavian languages
Studiar av genusendring i norsk har jamt over brukt mykje plass på inventaret i kategorien «ubestemt artikkel», som fleire stader viser teikn til å skrøkke frå tre til to typar. I dei fleste samanhengar vert dei tre typane refererte til som ein (m.), ei (f.) og eit (n.). Faktiske realiseringar som er subsumerte under desse typane, kan vere avgjerande i jakta på endringsforklaringar. Denne artikkelen undersøkjer korleis hokjønnsartikkelen har vore realisert i Oslo gjennom dei siste par hundre åra. Kjeldematerialet er eit breitt utval av litterære framstillingar og vitskaplege skildringar av oslomålet, og korpusdata frå nyare tid. Variasjonen som vert avdekt, er sjeldan tematisert i nyare framstillingar av genustilhøva i Oslo. Den tilsløringa som ei slik subsumering inneber, treng ikkje å ha uheldige konsekvensar for analysane av genussystemet i Oslo, men artikkelen argumenterer likevel for at eit meir nyansert medvit om variasjon i dei språklege realiseringane av artiklane er viktig for vidare genusforsking i andre dialektområde.
Philology. Linguistics, Germanic languages. Scandinavian languages
Andrespråksforskning er et komplekst forskningsområde, siden mange faktorer spiller inn i prosessen med å lære et nytt språk. Noen av faktorene kan ikke uten videre måles. Særlig vanskelig er det å måle subjektive faktorer, som innlærernes egne reaksjoner, holdninger og følelser. En måte å få innsikt i slike subjektive aspekter ved andrespråkslæring på, er å studere narrativer. Narrativer er personlige fortellinger, gjerne med et tidsaspekt eller en vending, der fortelleren deler erfaringer, opplevelser, vurderinger og følelser. I og med at individer er ulike og opplever språkopplæring ulikt, kan man ikke generalisere ut fra enkeltindividets opplevelser slik de formidles gjennom narrativer, men snarere erkjenne at disse gir innsikt i det mangfoldet av opplevelser som finnes.
I denne artikkelen presenterer vi ulike aspekter ved bruk av narrativer som metode i andrespråksforskning i norsk kontekst. Vi diskuterer fenomener man kan studere gjennom bruk av narrativ metode (f.eks. identitet, aktørskap og investeringer), ulike definisjoner av narrativer (sjanger versus tankeredskap), valg angående innhenting og klargjøring av narrativer til bruk i forskning, samt måter å analysere narrativer på. Vi konkluderer ved å peke på forskningshull i andrespråksfeltet i Norge som vi mener kan fylles ved bruk av narrativ metode.
El presente artículo explora una novela olvidada en la producción literaria de Hans Fallada: Der Alpdruck. Esta novela, testimonio del sufrimiento y la esperanza de la sociedad alemana en los primeros años posteriores a la Segunda Guerra Mundial, indaga en la herencia del nacionalsocialismo en la vida individual y colectiva. Conceptos centrales como el arraigo, la identidad y el lenguaje se transforman en elementos centrales para comprender las consecuencias del terror político y el dolor de una existencia desprovista de horizontes afectivos y reflexivos. El artículo se detiene en dichos conceptos tomando algunos capítulos de la novela para evidenciar la permanencia del nacionalsocialismo en diversos aspectos de los sujetos y el intento de lidiar con dicha herencia para pensar Alemania.
German literature, Germanic languages. Scandinavian languages
Any class of languages $\mathbf{L}$ accepted in time $\mathbf{T}$ has a counterpart $\mathbf{NL}$ accepted in nondeterministic time $\mathbf{NT}$. It follows from the definition of nondeterministic languages that $\mathbf{L} \subseteq \mathbf{NL}$. This work shows that every sufficiently powerful language in $\mathbf{L}$ contains a string corresponding to Gödel's undecidable proposition, but this string is not contained in its nondeterministic counterpart. This inconsistency in the definition of nondeterministic languages shows that certain questions regarding nondeterministic time complexity equivalences are irrevocably ill-posed.
This study focuses on a particular use of the interrogative pronoun hvað ‘what’ in Icelandic conversation. Besides occurring in open questions (e.g. hvað er þetta ‘what is this’), hvað can also be used as a discourse particle in repair sequences. Such occurrences typically occur in turns that contain either numeral information (time,
number or quantity) or names and other specific labels. The following two examples are drawn from the the spoken corpus ÍSTAL: (1) en ég hef einmitt er með hvað tuttuguogeinstommu skjá niðri í vinnu ‘but I have just have hvað twenty one inch screen down at work’, and (2) það heitir (þa-) (m-) eða þarna (niðr-) (það) sem var niðri í bæ hvað þarna Mjölnisholt ‘it is called (i-) (m-) or there (do-) (it) which was downtown hvað there Mjölnisholt’. In (1) and (2), hvað is used to structure a repair sequence that aims at solving problems that have arisen in the flow of the conversation. To be more specific, hvað functions as a repair initiator in self-initiated self-repairs. It is argued, on one hand, that the main role of the particle is to mark a minor inconsistency that may exist between what is said and what is actually the case (1), and, on the other, that the speaker is doing a word-search (2). The empirical data comprises around 20 hours of naturally occurring conversation from the ÍSTAL database recorded in 2000. In total, there are 25 sequences that contain an occurance of hvað as a discourse particle. The theoretical and methodological framework is conversation analysis and interactional linguistics.
Dictionaries and other general reference works, North Germanic. Scandinavian
Formal languages are sets of strings of symbols described by a set of rules specific to them. In this note, we discuss a certain class of formal languages, called regular languages, and put forward some elementary results. The properties of these languages are then employed to prove that there are infinitely many prime numbers.
We investigate certain word-construction games with variable turn orders. In these games, Alice and Bob take turns on choosing consecutive letters of a word of fixed length, with Alice winning if the result lies in a predetermined target language. The turn orders that result in a win for Alice form a binary language that is regular whenever the target language is, and we prove some upper and lower bounds for its state complexity based on that of the target language.
This paper proposes a new model for exploring the properties of English lexical affixes, based on exploiting the resources of English general-purpose dictionaries. Developed primarily for EFL university students and motivated by the highly inconsistent treatment of affixes in those dictionaries, this model builds around a heuristic self-study method and its accompanying bare-bones inferential dictionary (BBID), purposefully designed, produced and distributed as a guide to students' discoveries. The model has been devised so as to direct students away from affix entries in general-purpose dictionaries towards word entries which contain specific affixes and to lead students to discover the properties of target affixes by analysing corresponding source words provided in BBID. The exposition is divided into four parts, as follows: Section 1 brings some introductory, scene-setting remarks; in Section 2, essential and relational affixal properties are presented; in Section 3, the five major aspects of the new model are explained and exemplified: pragmatic reasons, main objectives, underlying principles, instructional material and real-life functioning; finally, Section 4 offers a summary and a critical assessment of the model and its BBID, together with a glimpse into their future.
Philology. Linguistics, Languages and literature of Eastern Asia, Africa, Oceania