Synthesizing minimal programs from traces of observable behaviour

Automatic synthesis of non-recursive flowchart programs from traces of observable behaviour is investigated. Our program synthesis algorithm described here can be applied to sets of sequences of stores yielding minimal programs being capable of reproducing these sequences. An efficient decision procedure for solvability of program synthesis problems is presented. An extension of PA admits four different types of input traces. For all four types program synthesis remains NP-complete even under various constraints

Specification, horizontal composition and parameterization of algebraic implementations

Loose specifications of abstract data types (ADTs) have many non-isomorphic algebras as models. An implementation between two loose Specifications should therefore consider many abstraction functions together with their source and target algebras. Just like specifications are stepwise refined to restrict their class of models, implementations should be stepwise refinable to restrict the class of abstraction functions. In this scenario specifications and implementations can be developed interwovenly. We suggest to have implementation specifications analogously to loose ADT specifications: Implementations have signatures, models, axioms and sentences thus constituting an institution. Implementation specifications are the theories of this institution and refinements between implementation specifications are its theory morphisms. In this framework, implementations between parameterized specifications and horizontal composition of implementations turn out to be special cases of the more powerful concept of parameterized implementations, which allow to instantiate an implementation by substituting a subimplementation by another implementation

Hierarchical structures and dynamic parameterization without parameters

Hierarchical structuring and parameterization concepts are investigated. It is argued that such concepts can be studied independently of a particular domain of application and orthogonally to the design of the ‘flat’ objects. A dynamic parameterization concept which disposes of the static declaration of formal parameters is proposed and realized in a hierarchy definition language. The methods suggested are illustrated by applying them to algebraic specifications, and it is shown how the approach extends the notion of an institution by a general structuring and parameterization concept

Parameterization-by-use for hierarchically structured objects

A formal model for hierarchical objects is presented. The hierarchical structure between objects is defined by a general notion of use relationship. Used objects may be regarded as formal parameters leading to the definition of parameter applications and a new parameterization concept called parameterization-by-use. We study hierarchies with all applications and give a canonical closure construction to generate such hierarchies. We show how these consepts can be incorporated into a specification language for hierarchically structured objects

On implementations of loose abstract data type specifications and their vertical composition

In an approach for the implementation of loose abstract data type specifications that completely distinguishes between the syntactical level of specifications and the semantical level of models, vertical implementation composition is defined compatibly on both levels. Implementations have signatures, models, and sentences where the latter also include hidden components, which allows for useful normal form results. We illustrate the stepwise development of implementations as well as their composition by some examples and describe the incorporation of the concept into an integrated software development and verification system

On the Modelling of an Agent's Epistemic State and its Dynamic Changes

Given a set of unquantified conditionals considered as default rules or a set of quantified conditionals such as probabilistic rules, an agent can build up its internal epistemic state from such a knowledge base by inductive reasoning techniques. Besides certain (logical) knowledge, epistemic states are supposed to allow the representation of preferences, beliefs, assumptions etc. of an intelligent agent. If the agent lives in a dynamic environment, it has to adapt its epistemic state constantly to changes in the surrounding world in order to be able to react adequately to new demands. In this paper, we present a high-level specification of the Condor system that provides powerful methods and tools for managing knowledge represented by conditionals and the corresponding epistemic states of an agent. Thereby, we are able to elaborate and formalize crucial interdependencies between different aspects of knowledge representation, knowledge discovery, and belief revision. Moreover, this specification, using Gurevich's Abstract State Machines, provides the basis for a stepwise refinement development process of the Condor system based on the ASM methodology

Modelling and Implementing a Knowledge Base for Checking Medical Invoices with DLV

Checking medical invoices, done by every health insurance company, is a labor-intensive task. Both speed and quality of executing this task may be increased by the knowledge-based decision support system ACMI which we present in this paper. As the relevant regulations also contain various default rules, ACMI`s knowledge core is modelled using the answer set programming paradigm. It turned out that all relevant rules could be expressed directly in this framework, providing for a declarative and easily extendable and modifiable knowledge base. ACMI is implemented using the DLV system