Incremental Confined Types Analysis

Research related to alias protection and related concepts, such as, confined types and ownership types has a long tradition and is a promising concept for the design and implementation of more reliable and secure software. Unfortunately, the use of these concepts is not widespread as most implementations are proofs of concept and fall short with respect to the integration with standard software development tools and processes. In this paper, we discuss an implementation of confined types based on Java 5 annotations. The contribution of this paper is twofold: First, we discuss the incrementalization of the confined types analysis and second, we present the integration of the analysis into Eclipse using the static analysis platform Magellan

Untyped Confluence in Dependent Type Theories

International audienceWe investigate techniques based on van Oostrom's decreasing diagrams that reduce confluence proofs to the checking of critical pairs in the absence of termination properties, which are useful in dependent type calculi to prove confluence on untyped terms. These techniques are applied to a complex example originating from practice: a faithful encoding, in an extension of LF with rewrite rules on objects and types, of a subset of the calculus of inductive constructions with a cumulative hierarchy of predicative universes above Prop. The rules may be first-order or higher-order, plain or modulo, non-linear on the right or on the left. Variables which occur non-linearly in lefthand sides of rules must take their values in confined types: in our example, the natural numbers. The first-order rules are assumed to be terminating and confluent modulo some theory: in our example, associativity, commutativity and identity. Critical pairs involving higher-order rules must satisfy van Oostrom's decreasing diagram condition wrt their indexes taken as labels

Assessing the impact of anthropogenic activities on groundwater quality in Maiduguri, Nigeria

This study investigates the impact of anthropogenic activities on groundwater quality; this was achieved by determining the concentration of potential anthropogenic contaminant indicator parameters such as nitrate, chloride, phosphate, and sulphate in the groundwater samples of the study area. A total of 30groundwater samples,15 each from the northern and southern partsof Maiduguri where obtained across a period of 2 months. Results ofthe groundwater analysesshowed that nitrate (NO3-) has mean concentration of 13.7mg/l in the northern part (site A), and 15.53 mg/l in the southern part (site B).Chloride (Cl-)has a mean concentration of 10.62 and 13.33 mg/l respectively in sites A and B. Sulphate (SO4-) has mean concentration of 3.52 mg/l in site A and 1.46 mg/l in site B. Lastly,phosphate (PO4-) has mean concentration of 1.39 and 1.52 mg/l in sites A and B respectively. The Mean concentrations were tested for their significant difference (p <0.05) across the boreholes of the two sites.Water quality results indicate that the impact of anthropogenic activities in the study area is low to moderate currently. The outcome of this paper will be useful in planning for sustainable groundwater management strategy

Regulating Data Exchange in Service Oriented Applications

We define a type system for COWS, a formalism for specifying and combining services, while modelling their dynamic behaviour. Our types permit to express policies constraining data exchanges in terms of sets of service partner names attachable to each single datum. Service programmers explicitly write only the annotations necessary to specify the wanted policies for communicable data, while a type inference system (statically) derives the minimal additional annotations that ensure consistency of services initial configuration. Then, the language dynamic semantics only performs very simple checks to authorize or block communication. We prove that the type system and the operational semantics are sound. As a consequence, we have the following data protection property: services always comply with the policies regulating the exchange of data among interacting services. We illustrate our approach through a simplified but realistic scenario for a service-based electronic marketplace

Featherweight Generic Confinement

Existing approaches to object encapsulation either rely on ad hoc syntactic restrictions or require the use of specialised type systems. Syntactic restrictions are difficult to scale and to prove correct, while specialised type systems require extensive changes to programming languages. We demonstrate that confinement can be enforced cheaply in Featherweight Generic Java, with no essential change to the underlying language or type system. This result demonstrates that polymorphic type parameters can simultaneously act as ownership parameters and should facilitate the adoption of confinement and ownership type systems in general-purpose programming languages

A relational model for confined separation logic

Confined separation logic is a new extension to separation logic designed to deal with problems involving dangling references within shared mutable structures. In par- ticular, it allows for reasoning about confinement in object- oriented programs. In this paper, we discuss the semantics of such an extension by defining a relational model for the overall logic, parametric on the shapes of both the store and the heap. This model provides a simple and elegant interpretation of the new confinement connectives and helps in seeking for duals. A number of properties of this logic are proved calculationally.Supported by NNSFC (No. 60573081