4,338 research outputs found
Software (Re-)Engineering with PSF III: an IDE for PSF
We describe the design of an integrated development environment (IDE) for
PSF. In the software engineering process we used process algebra in the form of
PSF for the specification of the architecture of the IDE. This specification is
refined to a PSF specification of the IDE system as a ToolBus application, by
applying vertical and horizontal implementation techniques. We implemented the
various tools as specified and connected them with a ToolBus script extracted
from the system specification
A Refinement Calculus for Logic Programs
Existing refinement calculi provide frameworks for the stepwise development
of imperative programs from specifications. This paper presents a refinement
calculus for deriving logic programs. The calculus contains a wide-spectrum
logic programming language, including executable constructs such as sequential
conjunction, disjunction, and existential quantification, as well as
specification constructs such as general predicates, assumptions and universal
quantification. A declarative semantics is defined for this wide-spectrum
language based on executions. Executions are partial functions from states to
states, where a state is represented as a set of bindings. The semantics is
used to define the meaning of programs and specifications, including parameters
and recursion. To complete the calculus, a notion of correctness-preserving
refinement over programs in the wide-spectrum language is defined and
refinement laws for developing programs are introduced. The refinement calculus
is illustrated using example derivations and prototype tool support is
discussed.Comment: 36 pages, 3 figures. To be published in Theory and Practice of Logic
Programming (TPLP
Modular Termination Verification
We propose an approach for the modular specification and verification of total correctness properties of object-oriented programs. We start from an existing program logic for partial correctness based on separation logic and abstract predicate families. We extend it with call permissions qualified by an arbitrary ordinal number, and we define a specification style that properly hides implementation details, based on the ideas of using methods and bags of methods as ordinals, and exposing the bag of methods reachable from an object as an abstract predicate argument. These enable each method to abstractly request permission to call all methods reachable by it any finite number of times, and to delegate similar permissions to its callees. We illustrate the approach with several examples
Neural Task Programming: Learning to Generalize Across Hierarchical Tasks
In this work, we propose a novel robot learning framework called Neural Task
Programming (NTP), which bridges the idea of few-shot learning from
demonstration and neural program induction. NTP takes as input a task
specification (e.g., video demonstration of a task) and recursively decomposes
it into finer sub-task specifications. These specifications are fed to a
hierarchical neural program, where bottom-level programs are callable
subroutines that interact with the environment. We validate our method in three
robot manipulation tasks. NTP achieves strong generalization across sequential
tasks that exhibit hierarchal and compositional structures. The experimental
results show that NTP learns to generalize well to- wards unseen tasks with
increasing lengths, variable topologies, and changing objectives.Comment: ICRA 201
Liberating Composition from Language Dictatorship
Historically, programming languages have been—although benevolent—dictators: fixing a lot of semantics into built-in language constructs. Over the years, (some) programming languages have freed the programmers from restrictions to use only built-in libraries, built-in data types, or built-in type checking rules. Even though, arguably, such freedom could lead to anarchy, or people shooting themselves in the foot, the contrary tends to be the case: a language that does not allow for extensibility, is depriving software engineers from the ability to construct proper abstractions and to structure software in the most optimal way. Instead, the software becomes less structured and maintainable than would be possible if the software engineer could express the behavior of the program with the most appropriate abstractions. The new idea proposed by this paper is to move composition from built-in language constructs to programmable, first-class abstractions in the language. As an emerging result, we present the Co-op concept of a language, which shows that it is possible with a relatively simple model to express a wide range of compositions as first-class concepts
Hiding variables when decomposing specifications into GR(1) contracts
We propose a method for eliminating variables from component specifications during the decomposition of GR(1) properties into contracts. The variables that can be eliminated are identified by parameterizing the communication architecture to investigate the dependence of realizability on the availability of information. We prove that the selected variables can be hidden from other components, while still expressing the resulting specification as a game with full information with respect to the remaining variables. The values of other variables need not be known all the time, so we hide them for part of the time, thus reducing the amount of information that needs to be communicated between components. We improve on our previous results on algorithmic decomposition of GR(1) properties, and prove existence of decompositions in the full information case. We use semantic methods of computation based on binary decision diagrams. To recover the constructed specifications so that humans can read them, we implement exact symbolic minimal covering over the lattice of integer orthotopes, thus deriving minimal formulae in disjunctive normal form over integer variable intervals
Modular specifications in process algebra
In recent years a wide variety of process algebras has been proposed in the literature. Often these process algebras are closely related: they can be viewed as homomorphic images, submodels or restrictions of each other. The aim of this paper is to show how the semantical reality, consisting of a large number of closely related process algebras, can be reflected, and even used, on the level of algebraic specifications and in process verifications. This is done by means of the notion of a module. The simplest modules are building blocks of operators and axioms, each block describing a feature of concurrency in a certain semantical setting. These modules can then be combined by means of a union operator +, an export operator â–ˇ, allowing to forget some operators in a module, an operator H, changing semantics by taking homomorphic images, and an operator S which takes subalgebras. These operators enable us to combine modules in a subtle way, when the direct combination would be inconsistent. We show how auxiliary process algebra operators can be hidden when this is needed. Moreover it is demonstrated how new process combinators can be defined in terms of the more elementary ones in a clean way. As an illustration of our approach, a methodology is presented that can be used to specify FIFO-queues, and that facilitates verification of concurrent systems containing these queues
- …