Session Types with Arithmetic Refinements

Session types statically prescribe bidirectional communication protocols for message-passing processes. However, simple session types cannot specify properties beyond the type of exchanged messages. In this paper we extend the type system by using index refinements from linear arithmetic capturing intrinsic attributes of data structures and algorithms. We show that, despite the decidability of Presburger arithmetic, type equality and therefore also subtyping and type checking are now undecidable, which stands in contrast to analogous dependent refinement type systems from functional languages. We also present a practical, but incomplete algorithm for type equality, which we have used in our implementation of Rast, a concurrent session-typed language with arithmetic index refinements as well as ergometric and temporal types. Moreover, if necessary, the programmer can propose additional type bisimulations that are smoothly integrated into the type equality algorithm

Rast: A Language for Resource-Aware Session Types

Traditional session types prescribe bidirectional communication protocols for concurrent computations, where well-typed programs are guaranteed to adhere to the protocols. However, simple session types cannot capture properties beyond the basic type of the exchanged messages. In response, recent work has extended session types with refinements from linear arithmetic, capturing intrinsic attributes of processes and data. These refinements then play a central role in describing sequential and parallel complexity bounds on session-typed programs. The Rast language provides an open-source implementation of session-typed concurrent programs extended with arithmetic refinements as well as ergometric and temporal types to capture work and span of program execution. To further support generic programming, Rast also enhances arithmetically refined session types with recently developed nested parametric polymorphism. Type checking relies on Cooper's algorithm for quantifier elimination in Presburger arithmetic with a few significant optimizations, and a heuristic extension to nonlinear constraints. Rast furthermore includes a reconstruction engine so that most program constructs pertaining the layers of refinements and resources are inserted automatically. We provide a variety of examples to demonstrate the expressivity of the language

Blockchain-Enabled Authenticated Key Agreement Scheme for Mobile Vehicles-Assisted Precision Agricultural IoT Networks

Precision Farming Has a Positive Potential in the Agricultural Industry Regarding Water Conservation, Increased Productivity, Better Development of Rural Areas, and Increased Income. Blockchain Technology is a Better Alternative for Storing and Sharing Farm Data as It is Reliable, Transparent, Immutable, and Decentralized. Remote Monitoring of an Agricultural Field Requires Security Systems to Ensure that Any Sensitive Information is Exchanged Only among Authenticated Entities in the Network. to This End, We Design an Efficient Blockchain-Enabled Authenticated Key Agreement Scheme for Mobile Vehicles-Assisted Precision Agricultural Internet of Things (IoT) Networks Called AgroMobiBlock. the Limited Existing Work on Authentication in Agricultural Networks Shows Passive Usage of Blockchains with Very High Costs. AgroMobiBlock Proposes a Novel Idea using the Elliptic Curve Operations on an Active Hybrid Blockchain over Mobile Farming Vehicles with Low Computation and Communication Costs. Formal and Informal Security Analysis Along with the Formal Security Verification using the Automated Validation of Internet Security Protocols and Applications (AVISPA) Software Tool Have Shown the Robustness of AgroMobiBlock Against Man-In-The-Middle, Impersonation, Replay, Physical Capture, and Ephemeral Secret Leakage Attacks among Other Potential Attacks. the Blockchain-Based Simulation on Large-Scale Nodes Shows the Computational Time for an Increase in the Network and Block Sizes. Moreover, the Real-Time Testbed Experiments Have Been Performed to Show the Practical Usefulness of the Proposed Scheme

On Petri Nets with Hierarchical Special Arcs

We investigate the decidability of termination, reachability, coverability and deadlock-freeness of Petri nets endowed with a hierarchy of places, and with inhibitor arcs, reset arcs and transfer arcs that respect this hierarchy. We also investigate what happens when we have a mix of these special arcs, some of which respect the hierarchy, while others do not. We settle the decidability status of the above four problems for all combinations of hierarchy, inhibitor, reset and transfer arcs, except the termination problem for two combinations. For both these combinations, we show that deciding termination is as hard as deciding the positivity problem on linear recurrence sequences -- a long-standing open problem

Utilisation of adolescent reproductive and sexual health services in a rural area of West Bengal: A mixed-method study

Introduction: Despite policy actions and strategic efforts for improving the reproductive and sexual health of adolescents by promoting the uptake of adolescent reproductive and sexual health (ARSH) services, the utilisation rate remains significantly low, especially in rural areas of India. This study aimed to assess the utilisation of these services by adolescents in rural West Bengal and its associated determinants. Methods: This mixed-method study was conducted from May to September 2021 in the Gosaba rural block of South 24 Parganas, West Bengal. Quantitative data were collected from 326 adolescents using a pre-tested structured questionnaire. Qualitative data were collected via four focus group discussions among 30 adolescents and key-informant interviews among six healthcare workers. Quantitative data were analysed using SPSS, while qualitative data were analysed thematically. Results: Ninety-six (29.4%) adolescents had utilised ARSH services at least once during adolescence. The factors associated with non-utilisation of ARSH services were younger age, female sex, increasing reproductive health stigma and decreasing parent–adolescent communication related to sexual health. Qualitative exploration revealed that unawareness regarding services, perceived lack of privacy and confidentiality at healthcare facilities and disruption of services post-emergence of the COVID-19 pandemic were some major barriers to ARSH service utilisation. Conclusion: A multi-component strategy, including promotion of adolescent-friendly health clinics, community support interventions associated with motivation and counselling of parents regarding the importance of adolescent reproductive health, is needed to improve the utilisation of ARSH services. Necessary steps to correct the deficiencies at the facility level should also be prioritised