A coordination language for mobile components

Abstract In this paper we present the sigmapi coordination language, a core language for specifying dynamic networks of components. The language is inspired by the Manifold coordination language and by the pi-calculus. The main concepts of the language are components, classes, objects and channels. A program in sigmapi consists of a number of components, where each component is a collection of classes separable from its original context and re-usable in any other context. An object is an instance of a class that executes in parallel with the other objects active in the system. The sigmapi language differs from other models of object-oriented systems mainly in its treatment of communication and mobility: communication is anonymous via synchronous or asynchronous channels, while mobility is obtained by moving channels in the virtual space of linked objects. Thus, a channel is a transferable capability of communication, and objects are mobile in the sense that their communication possibilities may change during a computation. The language sigmapi itself does not impose exogenous coordination, meaning that the coordination primitives affecting each object can be executed within the computation of the object itself. However, only simple restrictions on the class-definitions of a sigmapi program suffice to enforce a separation between computation and coordination. Interaction typically occurs anonymously and under the full control of the objects involved. This make it easier to deal with Internet application where security policies must be enforced in view of the possibilities of attacks

A logical interface description language for components

Motivated by our earlier work on the IWIM model and the Manifold language, in this paper, we attend to some of the basic issues in component-based software. We present a formal model for such systems, a formal-logic-based component interface description language that conveys the observable semantics of components, a formal system for deriving the semantics of a composite system out of the semantics of its constituent components, and the conditions under which this derivation system is sound and complete. Our main results in this paper are the theorems that formulate the notion of compositionality and the completeness of the derivation system that supports this property in a component-based system

Programming and Deployment of Active Objects with Application-Level Scheduling

We extend and implement a modeling language based on concurrent active objects with application-level scheduling policies. The language allows a programmer to assign pri- orities at the application level, for example, to method def- initions and method invocations, and assign corresponding policies to the individual active objects for scheduling the messages. Thus, we leverage scheduling and performance related issues, which are becoming increasingly important in multi-core and cloud applications, from the underlying operating system to the application level. We describe a tool-set to transform models of active objects extended with application-level scheduling policies into Java. This tool-set allows a direct use of Java class libraries; thus, we obtain a full-fledged programming language based on active objects which allows for high-level control of deployment related is- sues

Monitoring method call sequences using annotations

In this paper we introduce JMSeq, a Java-based tool for monitoring sequences of method calls. JMSeq provides a simple but expressive language to specify the observables of a Java program in terms of sequences of possibly nested method calls. Similar to many monitoring-oriented environments, verification in JMSeq is done at run-time; unlike all other approaches based on aspect-oriented programming, JMSeq uses code annotation rather than instrumentation, and therefore is suitable for component-based software verification

Symbolic execution formally explained

In this paper, we provide a formal explanation of symbolic execution in terms of a symbolic transition system and prove its correctness and completeness with respect to an operational semantics which models the execution on concrete values.We first introduce a formalmodel for a basic programming languagewith a statically fixed number of programming variables. This model is extended to a programming language with recursive procedures which are called by a call-by-value parameter mechanism. Finally, we present a more general formal framework for proving the soundness and completeness of the symbolic execution of a basic object-oriented language which features dynamically allocated variables.Computer Science

Language-dependency of /m/ in L1 Dutch and L2 English

NWO276-75-010Theoretical and Experimental Linguistic

Individual variation in filled pauses in the native and second language

Individual variation in filled pauses in the native and second language Meike de Boer & Willemijn Heeren Leiden University Centre for Linguistics Hesitation behavior is a relatively unconscious part of language [1], which shows much between-speaker variation [2−4]. Furthermore, individuals are rather consistent in how they hesitate in their native language [2, 5]. This study investigates between-speaker variation in hesitation behavior in the first (L1) and second (L2) language, and within-speaker consistency of filled pauses across languages. In Dutch and English, two fillers are mainly used to express hesitation: uh and um. However, their exact phonetic realization and the ratio between the two are different for these languages [6, 7]. Flege’s Speech Learning Model [8] says that L2 learners only adapt their pronunciation when they perceive a difference between the L1 and L2. Therefore, we expect that Dutch speakers of English more clearly adapt their uh:um proportions than their vowel formants of the uh/um vowels. For other pronunciation features of uh and um, e.g. duration and fundamental frequency (F0), we expect speakers to be consistent across languages [9, 2]. We investigated the speech of 40 Dutch students of University College Utrecht (20 females; 20 males). The speakers were selected from the Longitudinal Corpus of University College English Accents (LUCEA), collected by Orr and Quené [10]. Students from University Colleges have advanced L2 proficiency. Preliminary results show substantial between-speaker variation in the filled pauses uh and um in both Dutch and English. The within-speaker consistency was low where expected: when speaking English, students used the um variant more often than in Dutch. Also, the vowel quality of their filled pauses was pronounced more open and more backwards in English than in Dutch. According to the SLM, this suggests that differences in vowel realization between Dutch and English were sufficiently salient to these speakers, as were the different uh:um ratios. As expected, filled pauses’ durations and F0 remained relatively stable across languages. References [1] Clark, H. H., & Fox Tree, J. E. (2002). Using uh and um in spontaneous speaking. Cognition, 84, 73−111. [2] Braun, A., Rosin, A. (2015). On the speaker-specificity of hesitation markers. Proc. 18th ICPhS Glasgow, 731−736. [3] Hughes, V., Wood, S., & Foulkes, P. (2016). Filled pauses as variables in forensic voice comparison. Int. J. Speech Lang. Law, 23, 99−132. [4] McDougall, K., & Duckworth, M. (2017). Profiling fluency: An analysis of individual variation in disfluencies in adult males. Speech Comm., 95, 16−27. [5] Künzel, H. F. (1997). Some general phonetic and forensic aspects of speaking tempo. For. Linguist., 4, 48−83. [6] De Leeuw, E. (2007). Hesitation markers in English, German, and Dutch. J. Germ. Ling. 19, 85–114. [7] Wieling, M., Grieve, J., Bouma, G., Fruehwald, J., Coleman, J., & Liberman, M. (2016). Variation and change in the use of hesitation markers in Germanic languages. Language Dynamics and Change, 6, 199−234. [8] Flege, J. E. (1995). Second language speech learning: Theory, findings, and problems. In: Strange, W. (Ed.), Speech Perception and Linguistic Experience: Issues in Cross-Language Research. York: York Press, 233−277. [9] Kolly, M. J., Leemann, A., De Mareüil, P. B., & Dellwo, V. (2015). Speaker-idiosyncrasy in pausing behavior: Evidence from a cross-linguistic study. Proc. 18th ICPhS Glasgow, 294−299. [10] Orr, R., & Quené, H. (2017). D-LUCEA: Curation of the UCU Accent Project data. In: Odijk, J., & Van Hessen, A. (Eds.), CLARIN in the Low Countries. London: Ubiquity Press, 177–190. NWOTheoretical and Experimental Linguistic

Cross-linguistic filled pause realization: the acoustics of uh and um in native Dutch and non-native English

It has been claimed that filled pauses are transferred from the first (L1) into the second language (L2), suggesting that they are not directly learned by L2 speakers. This would make them usable for cross-linguistic forensic speaker comparisons. However, under the alternative hypothesis that vowels in the L2 are learnable, L2 speakers adapt their pronunciation. This study investigated whether individuals remain consistent in their filled pause realization across languages, by comparing filled pauses (uh, um) in L1 Dutch and L2 English by 58 females. Next to the effect of language, effects of the filled pauses' position in the utterance were considered, as these are expected to affect acoustics and also relate to fluency. Mixed-effects models showed that, whereas duration and fundamental frequency remained similar across languages, vowel realization was language-dependent. Speakers used um relatively more often in English than Dutch, whereas previous research described speakers to be consistent in their um:uh ratio across languages. Results furthermore showed that filled-pause acoustics in the L1 and L2 depend on the position in the utterance. Because filled pause realization is partially adapted to the L2, their use as a feature for cross-linguistic forensic speaker comparisons may be restricted.NWO276-75-010Theoretical and Experimental Linguistic

The speaker-specificity of filled pauses: A cross-linguistic study

We investigated the speaker-specificity of filled pauses across languages and time. The filled pauses uh and um contain speaker-specific information in a speaker’s native language. Since speakers are relatively unaware of their hesitation behavior, it might transfer from their first (L1) to their second language (L2). We examined filled pauses using several phonetic-acoustic features in spontaneous  L1 Dutch and L2 English speech of 20 female speakers, recorded at two times, three years apart.Using linear mixed-effects models, we found that speakers differ in their first and second formants of uh and um in L1 versus L2, while duration and fundamental frequency remain stable. Speaker classification models trained on filled pauses in one language perform worse – but still relatively well – on the other language. With the exception of a few speakers, hesitation behavior remained stable over time. In spite of L1-L2 differences, some speaker characteristics of filled pauses remain.NWO276-75-010Theoretical and Experimental Linguistic