Relating Church-Style and Curry-Style Subtyping

Type theories with higher-order subtyping or singleton types are examples of systems where computation rules for variables are affected by type information in the context. A complication for these systems is that bounds declared in the context do not interact well with the logical relation proof of completeness or termination. This paper proposes a natural modification to the type syntax for F-Omega-Sub, adding variable's bound to the variable type constructor, thereby separating the computational behavior of the variable from the context. The algorithm for subtyping in F-Omega-Sub can then be given on types without context or kind information. As a consequence, the metatheory follows the general approach for type systems without computational information in the context, including a simple logical relation definition without Kripke-style indexing by context. This new presentation of the system is shown to be equivalent to the traditional presentation without bounds on the variable type constructor.Comment: In Proceedings ITRS 2010, arXiv:1101.410

TDOA--based localization in two dimensions: the bifurcation curve

In this paper, we complete the study of the geometry of the TDOA map that encodes the noiseless model for the localization of a source from the range differences between three receivers in a plane, by computing the Cartesian equation of the bifurcation curve in terms of the positions of the receivers. From that equation, we can compute its real asymptotic lines. The present manuscript completes the analysis of [Inverse Problems, Vol. 30, Number 3, Pages 035004]. Our result is useful to check if a source belongs or is closed to the bifurcation curve, where the localization in a noisy scenario is ambiguous.Comment: 11 pages, 3 figures, to appear in Fundamenta Informatica

D-Branes on C^3_6 part I: prepotential and GW-invariants

This is the first of a set of papers having the aim to provide a detailed description of brane configurations on a family of noncompact threedimensional Calabi-Yau manifolds. The starting point is the singular manifold C^3/Z_6, which admits five distinct crepant resolutions. Here we apply local mirror symmetry to partially determine the prepotential encoding the GW-invariants of the resolved varieties. It results that such prepotential provides all numbers but the ones corresponding to curves having null intersection with the compact divisor. This is realized by means of a conjecture, due to S. Hosono, so that our results provide a check confirming at least in part the conjecture.Comment: 66 pages, 18 figures, 15 tables; added reference

A comprehensive analysis of the geometry of TDOA maps in localisation problems

In this manuscript we consider the well-established problem of TDOA-based source localization and propose a comprehensive analysis of its solutions for arbitrary sensor measurements and placements. More specifically, we define the TDOA map from the physical space of source locations to the space of range measurements (TDOAs), in the specific case of three receivers in 2D space. We then study the identifiability of the model, giving a complete analytical characterization of the image of this map and its invertibility. This analysis has been conducted in a completely mathematical fashion, using many different tools which make it valid for every sensor configuration. These results are the first step towards the solution of more general problems involving, for example, a larger number of sensors, uncertainty in their placement, or lack of synchronization.Comment: 51 pages (3 appendices of 12 pages), 12 figure

Developing Multiliteracies Through Digital Storytelling. A Case Study of Learners of Italian as a Foreign Language

Multiliteracy approaches are based on enhancing students’ agency and participation, which can be fostered by integrating digital storytelling into linguistic activities. However, literature lacks practical examples of how students can develop multiliteracies in learning Italian as a foreign language with digital storytelling. This article attempts to fill this gap by presenting the results of task-based language learning activities conducted on students of Italian as a foreign language with the digital storytelling platforms Wakelet and izi.Travel. Evidence will show how multiliteracies manifested in agency, creativity and social engagement

Higher-order subtyping and its decidability

AbstractWe define the typed lambda calculus Fω∧ (F-omega-meet), a natural generalization of Girard's system Fω (F-omega) with intersection types and bounded polymorphism. A novel aspect of our presentation is the use of term rewriting techniques to present intersection types, which clearly splits the computational semantics (reduction rules) from the syntax (inference rules) of the system. We establish properties such as Church-Rosser for the reduction relation on types and terms, and strong normalization for the reduction on types. We prove that types are preserved by computation (subject reduction), and that the system satisfies the minimal types property. We define algorithms for type checking and subtype checking. The development culminates with the proof of decidability of typing in Fω∧, containing the first proof of decidability of subtyping of a higher-order lambda calculus with subtyping

The Effects of Virtual Museums on Students’ Positive Interdependence in learning Italian as a Foreign Language

Evidence suggests that positive interdependence is the foundation of language learning and task-based interactions, linking museums to educational institutions in fostering visitor communication with artwork through Foreign Language (FL) use. Despite the increasing adoption of digital resources in education, little research has yet been devoted to the effects of virtual museums on language students’ positive interdependence. This paper discusses the results of interventions conducted on 15 students of Italian as a FL with the digital collection of Palazzo Ducale in Venice. By assessing their impact on learners’ interactions, virtual museums are shown to increase positive interdependence through cooperation, turn-taking, negotiation and role-assignment during task-based language activities

THE IMPACT OF A POST-PANDEMIC EDUCATIONAL TECHNOLOGY TRAINING ON USABILITY AND ACCEPTANCE BY TEACHERS OF ITALIAN AS A FOREIGN LANGUAGE

The implementation of technologies in language learning classrooms has been accelerated by the Covid-19 pandemic, with a consequential boost in the evolution of educational methodologies towards blending in-person with remote teaching. Consequently, it is necessary that teachers are given opportunities to train their technological competences to conduct and manage an increasingly digitalized language learning environment. Despite the importance of digital approaches to language education, research on the impact of technologies on the teachers’ acceptance and endorsement of digital tools in educational settings are limited, especially with regards to teaching Italian as an L2. Therefore, this article bridges this gap by analyzing the potential implications of a technology-based methodological training on teachers’ adoption and implementation of technologies in educational contexts. It presents the results of a mixed-methods investigation conducted on a group of Italian L2 teachers taking a four-weeks training course on educational technology. Teachers took pre- and post-course TAM tests (Davis, 1989) and participated to online focus groups. Results confirmed the successful impact of the training course on teachers’ acceptance of digital tools and practices. However, the positive effects of technology use on the linguistic competence of Italian L2 students was debated by the teachers. By further investigating survey and focus group responses, this article provides evidence for encouraging teachers’ integrations of technologies in Italian L2 educational contexts. L’impatto sulla loro usabilità e accettazione da parte degli insegnanti di italiano come lingua straniera di una formazione post-pandemica sulle tecnologie didattiche L’uso delle tecnologie digitali nelle classi di lingua straniera ha subito un’accelerazione con la pandemia di Covid-19, con una conseguente evoluzione di metodologie glottodidattiche ibride che combinano l’insegnamento da remoto con quello in presenza. È diventato dunque necessario sostenere la formazione tecnologica di insegnanti per permettere loro di gestire e condurre lezioni di lingua. Nonostante l’importanza di approcci digitali alla didattica linguistica, poche ricerche sono state dedicate all’impatto delle tecnologie sull’accettazione e l’utilizzo di strumenti digitali da parte di docenti, specialmente per quanto riguarda l’insegnamento dell’italiano L2. Per cercare di colmare tali lacune, questo articolo presenta i risultati di un’indagine sull’accettazione e l’applicazione di strumenti digitali da parte di un gruppo di insegnanti di italiano L2 iscritti ad un corso di formazione sulle tecnologie educative. I docenti hanno risposto a questionari TAM (Davis, 1989) e partecipato a focus groups online. I risultati hanno dimostrato l’impatto positivo del corso sui livelli di accettazione e di pratica didattica con le tecnologie da parte degli insegnanti, che hanno però aperto un dibattito riguardo ai benefici delle tecnologie digitali sulle competenze linguistiche di studenti di italiano L2. Attraverso l’analisi delle risposte degli insegnanti ai questionari e alle interviste, l’articolo evidenzierà l’importanza di favorire l’integrazione delle tecnologie digitali in contesti di glottodidattica dell’italiano L2

The algebro-geometric study of range maps

Localizing a radiant source is a widespread problem to many scientific and technological research areas. E.g. localization based on range measurements stays at the core of technologies like radar, sonar and wireless sensors networks. In this manuscript we study in depth the model for source localization based on range measurements obtained from the source signal, from the point of view of algebraic geometry. In the case of three receivers, we find unexpected connections between this problem and the geometry of Kummer's and Cayley's surfaces. Our work gives new insights also on the localization based on range differences.Comment: 38 pages, 18 figure