We give an overview of the enhanced VSE system which is a tool to formally specify and verify systems. It provides means for struc-turing speciications and it supports the development process from the speciication of a system to the code generation. Formal developments following this method are stored and maintained in an administration system that guides the user and maintains a consistent sta...

Deduction chains represent a syntactic and in a certain sense constructive method for proving completeness of a formal system. Given a formula φ, the deduction chains of φ are built up by systematically decomposing φ into its subformulae. In the case where φ is a valid formula, the decomposition yields a (usually cut-free) proof of φ. If φ is not valid, the decomposition produces a countermodel...

We prove in HOL that three proof systems for classical rst-order predicate logic, the Hilbertian axiomatization, the system of natural deduction, and a variant of sequent calculus, are isomorphic. The isomorphism is in the sense that provability of a conclusion from hypotheses in one of these proof systems is equivalent to provability of this conclusion from the same hypotheses in the others. P...

In context-aware systems, one of the main challenges is how to tackle context uncertainty well, since perceived context always yields uncertainty and ambiguity with consequential effect on the performance of context-aware systems. We argue that uncertainty is mainly generated by two sources. One is sensor’s inherent inaccuracy and unreliability. The other source is deduction process from low-le...

GLD's eight deduction operations consist of six inference operations extension, unit subsumed extension, A-reduction, identical A-reduction, C-reduction, and identical C-reduction; and two bookkeeping operations A-truncation and C-truncation. The extension operations are, in combination, equivalent to the extension operations of other chain format systems. GLD's reduction operations combine fea...