Validating specifications of dynamic systems using automated reasoning techniques

In this paper, we propose a new approach to validating formal specifications of observable behavior of discrete dynamic systems. By observable behavior we mean system behavior as observed by users or other systems in the environment of the system. Validation of a formal specification of an informal domain tries to answer the question whether the specification actually describes the intended domain. This differs from the verification problem, which deals with the correspondence between formal objects, e.g. between a formal specification of a system and an implementation of it. We consider formal specifications of object-oriented dynamic systems that are subject to static and dynamic integrity constraints. To validate that such a specification expresses the intended behavior, we propose to use a tool that can answer reachability queries. In a reachability query we ask whether the system can evolve from one state into another without violating the integrity constraints. If the query is answered positively, the system should exhibit an example path between the states; if the answer is negative, the system should explain why this is so. An example path produced by the tool can be used to produce scenarios for presentations of system behavior, but can also be used as a basis for acceptance testing. In this paper, we discuss the use of planning and theoremproving techniques to answer such queries, and illustrate the use of reachability queries in the context of information system development

LCM 3.0: A Language for describing Conceptual Models

The syntax of the conceptual model specification language LCM is defined. LCM uses equational logic to specify data types and order-sorted dynamic logic to specify objects with identity and mutable state. LCM specifies database transactions as finite sets of atomic object transitions

The university library document circulation system specified in LCM

The specification language LCM (Conceptual Modeling Language) is used to specify part of the university library document circulation system of the Free University. LCM was previously called CMSL

Validating database constraints and updates using automated reasoning techniques

In this paper, we propose a new approach to the validation of formal specifications of integrity constraints. The validation problem of fornmal specifications consists of assuring whether the formal specification corresponds with what the domain specialist intends. This is distinct from the verification problem, which is the problem whether an implementation (which is a formal object) corresponds with a specification (which is also a formal object). We consider formal specifications of object-oriented database systems that are subject to static and dynamic integrity constraints. To validate that such a specification expresses what we intend, we propose a system that can answer reachability queries, in which it is asked whether the system can evolve from one state into another without violating the integirty constraints. If the query is answered positively, the system should exhibit an example path between the two states; if the answer is negative, the system should explain why this is so. We discuss the use of planning and theorem-proving techniques to answer such queries, illustrating their application to reachability queries relevant for database system validation

Second virial coefficient at the critical point in a fluid of colloidal spheres plus depletants

Vliegenthart-Lekkerkerker (VL) criterion B2 = 6vc for second virial coefficient B2 at the critical (colloidal) gas-liquid point is considered for a mixture of spheres with volume vc plus depletants. For the onset of fluid-phase instability, the VL criterion holds for a wide range of shapes of direct attractive forces between hard-core spheres (Vliegenthart, G. A.; Lekkerkerker, H. N. W. J. Chem. Phys. 2000, 112, 5364). In the case of long-ranged attractions imposed indirectly via depletants, it is found that the VL relation fails. Instead, B2/vc at the critical point depends strongly on the sphere/depletant size ratio. By making the hard spheres sticky, we find that B2 moves gradually toward the VL criterion upon increasing the stickiness

Second virial coefficient at the critical point in a fluid of colloidal spheres plus depletants

Vliegenthart-Lekkerkerker (VL) criterion B2 = 6vc for second virial coefficient B2 at the critical (colloidal) gas-liquid point is considered for a mixture of spheres with volume vc plus depletants. For the onset of fluid-phase instability, the VL criterion holds for a wide range of shapes of direct attractive forces between hard-core spheres (Vliegenthart, G. A.; Lekkerkerker, H. N. W. J. Chem. Phys. 2000, 112, 5364). In the case of long-ranged attractions imposed indirectly via depletants, it is found that the VL relation fails. Instead, B2/vc at the critical point depends strongly on the sphere/depletant size ratio. By making the hard spheres sticky, we find that B2 moves gradually toward the VL criterion upon increasing the stickiness

Minimal Semantics for Action Specifications in PDL

In this paper we investigate minimal semantics for Propositional Dynamic Logic formulas. The goal is to be able to write action specifications in a declarative pre/post condition style. The declarative specification of actions comes with some well known problems: the frame problem, the qualification problem and the ramification problem. We incorporate the assumptions that are inherent to both the frame and the qualification problem into the semantics of Dynamic Logic by defining preferences over Dynamic logic models. This gives us an intended semantics that, for each declarative action specification, selects a unique meaning for each action

Minimal Semantics for Transaction Specifications in a Multi-modal Logic

This paper presents an extension of propositional dynamic database logic in which the specification writer can specify arbitrary database transactions declaratively. Since declaratively specified transactions are under-specified, the specification must be supplemented with a frame assumption about what does not change as the result of a transaction. In addition, static database constraints imply preconditions, also called qualifications , that must be satisfied for a transaction to occur and static constraints may imply derived updates for a transaction (also called ramifications). We solve these problems by defining preferences over Kripke structures and showing how these can be used to define an intended semantics that, for each declarative transaction specification, selects a unique meaning for each transaction. In particular, the intended semantics formalizes a frame assumption and selects qualifications and ramifications for each specification. The notion of preferential entailmen..