Energy Mean-Payoff Games

In this paper, we study one-player and two-player energy mean-payoff games. Energy mean-payoff games are games of infinite duration played on a finite graph with edges labeled by 2-dimensional weight vectors. The objective of the first player (the protagonist) is to satisfy an energy objective on the first dimension and a mean-payoff objective on the second dimension. We show that optimal strategies for the first player may require infinite memory while optimal strategies for the second player (the antagonist) do not require memory. In the one-player case (where only the first player has choices), the problem of deciding who is the winner can be solved in polynomial time while for the two-player case we show co-NP membership and we give effective constructions for the infinite-memory optimal strategies of the protagonist

Non-Deterministic Functions as Non-Deterministic Processes

We study encodings of the ?-calculus into the ?-calculus in the unexplored case of calculi with non-determinism and failures. On the sequential side, we consider ?^?_?, a new non-deterministic calculus in which intersection types control resources (terms); on the concurrent side, we consider ??, a ?-calculus in which non-determinism and failure rest upon a Curry-Howard correspondence between linear logic and session types. We present a typed encoding of ?^?_? into ?? and establish its correctness. Our encoding precisely explains the interplay of non-deterministic and fail-prone evaluation in ?^?_? via typed processes in ??. In particular, it shows how failures in sequential evaluation (absence/excess of resources) can be neatly codified as interaction protocols

Non-Deterministic Functions as Non-Deterministic Processes

We study encodings of the λ-calculus into the π-calculus in the unexplored case of calculi with non-determinism and failures. On the sequential side, we consider λ^↯_⊕, a new non-deterministic calculus in which intersection types control resources (terms); on the concurrent side, we consider sπ, a π-calculus in which non-determinism and failure rest upon a Curry-Howard correspondence between linear logic and session types. We present a typed encoding of λ^↯_⊕ into sπ and establish its correctness. Our encoding precisely explains the interplay of non-deterministic and fail-prone evaluation in λ^↯_⊕ via typed processes in sπ. In particular, it shows how failures in sequential evaluation (absence/excess of resources) can be neatly codified as interactio

Types and Terms Translated:Unrestricted Resources in Encoding Functions as Processes

Type-preserving translations are effective rigorous tools in the study of core programming calculi. In this paper, we develop a new typed translation that connects sequential and concurrent calculi; it is governed by type systems that control resource consumption. Our main contribution is the source language, a new resource λ-calculus with non-collapsing non-determinism and failures, dubbed uλ^{↯}_{⊕}. In uλ^{↯}_{⊕}, resources are split into linear and unrestricted; failures are explicit and arise from this distinction. We define a type system based on intersection types to control resources and fail-prone computation. The target language is 𝗌π, an existing session-typed π-calculus that results from a Curry-Howard correspondence between linear logic and session types. Our typed translation subsumes our prior work; interestingly, it treats unrestricted resources in uλ^{↯}_{⊕} as client-server session behaviours in 𝗌π

A framework for providing mobile centric services to students at higher education institutions : the case of open distance learning

In developing countries, the mobile phone market has matured in terms of subscription, penetration and mobile centric1 services. In turn, people have integrated mobile phones into their daily lives. The interaction opportunities that have evolved in business and social life have given students at Higher Educational Institutions (HEIs) grounds to anticipate similar opportunities within their learning environments. In the context of developing countries, students primarily access information through mobile phones and there seems to be a disconnection between how HEI provide informational services and how students want to access the services. Therefore, HEIs are challenged with shifting from their traditional information distribution practices into integrating mobile centric services. Literature describes several models of providing mobile centric services in learning settings but there is a paucity of research that address the disconnection between students’ mobile centric needs and expectations against the HEIs’ provision of such services. Therefore, this study proposes a Framework for providing mobile centric services to students at HEIs in Open Distance e-Learning (ODeL) context in South Africa. The potential contribution of the framework is that it can facilitate strategic planning and implementation of mobile centric services whilst ensuring the needed synergies with students and academics. The research is grounded in interpretive philosophy and was undertaken as a single case study. The case study employed mixed method design for data collection. The advantage of mixed method design is that it enables both qualitative and quantitative data to be collected from a variety of sources and triangulation of results to get a complete picture of the phenomenon under study. The research was undertaken in four phases. Phase 1 of the study was a literature analysis carried out to identify the components for providing mobile centric services that facilitate students with information access and interaction. The objective was to provide a conceptual framework that would direct the search for evidence and organise the results. Phase 2 of the study employed the conceptual framework developed in Phase 1 to identify the units of analysis and to design the data collection instruments. Phase 3 of the study focused on collecting data within a single case study with embedded units of analysis. Data collection included Policy document analysis, Tool observation analysis, Student surveys and Lecturer interviews. The data collected from the case study was analysed with the view of enhancing the components of the conceptual framework developed in Phase 1. The enhancement of the components of the conceptual framework carried out in Phase 3 directed the development of the Framework for providing mobile centric services to students at HEIs in ODeL context in South Africa as presented in Phase 4. This adds new knowledge in addressing the literature gap between the mobile centric needs and expectations of students and the provision of mobile centric services at HEIs. The framework has practical value in that its components can guide HEIs in determining the mobile centric readiness of their institutions, the needs of the stakeholders, the context of use, the identification of mobile centric resources and the managing of constraints. Mobile centric refers to the preference of accessing and interacting with information services through a mobile device such as a mobile phone.ComputingPh. D. (Information Systems