of applying arbitrary action models to the Kripke model [10]. Refinement modal logics add quantifiers over such refinements to existing modal logics. Work by van Ditmarsch, French and Pinchinat [11] gave an axiomatisation for the refinement modal logic over the class of unrestricted Kripke models, for a

Map interpretation remains a critical step in solving the structure of a macromolecule. Errors introduced at this early stage may persist throughout crystallo-graphic refinement and result in an incorrect struc-ture. The normally quoted crystallographic residual is often a poor description

We present an abstraction refinement technique for the verification of universally quantified array assertions such as “all elements in the array are sorted”. Our technique can be seamlessly combined with existing software model checking algorithms. We implemented our technique in the ACSAR

overhead is small. OCB refines a scheme, IAPM, suggested by Jutla [20]. Desirable properties of OCB include: the ability to encrypt a bit string of arbitrary length into a ciphertext of minimal length; cheap o#set calculations; cheap session setup, a single underlying cryptographic key; no extended

STP is a decision procedure for the satisfiability of quantifier-free formulas in the theory of bit-vectors and arrays that has been optimized for large problems encountered in software analysis applications. The basic architecture of the procedure consists of word-level pre-processing algorithms

Cell cloning by limiting dilution in 96-well microtiter plates has been employed to isolate colonies of human T-lympho-cytes resistant to the purine analogue, 6-thioguanine (TG). These colonies show stability of the TG-resistant (TG1) phenotype, lack hypoxanthine guanine phosphoribosyl trans-ferase (HPRT) activity and thus appear to be the result of in vivo somatic cell mutation events. In order to employ this T-lymphocyte cloning assay for quantitative determination of the in vivo TGr mutant frequency in humans, we have defined the optimal conditions for T-cell colony formation with both nonselected and TG-selected cells. The parameters investigated include medium, serum, amount of the mitogen phytohaemagghitinin, amount of T-cell growth factor (TCGF) and the number of irradiated feeder or accessory ceils. Under the optimal conditions, the fraction of positive wells is pro-portional to the number of cells plated per well with both nonselection and TG selection conditions. T-cell cloning ef-ficiencies therefore are independent of inoculum size. There was some evidence for a decline in TGr mutant cell cloning at densities> 2 X 104 cells per round-bottom well, possibly due to metabolic cooperation between wild-type and mutant cells. The conditions defined in this study appear to provide a quantitative measurement of the in vivo TGr mutant fre-quency in human T-lymphocytes.

Abstract. Interpolating provers have a variety of applications in verification, including invariant generation and abstraction refinement. Here, we extended these methods to produce universally quantified interpolants and invariants, allowing the verification of programs manipulating arrays

Abstract. We investigate the complexity of satisfiability for one-agent Refinement Modal Logic (RML), a known extension of basic modal logic (ML) obtained by adding refinement quantifiers on structures. It is known that RML has the same expressiveness as ML, but the translation of RML into ML

An approach for automatically generating loop invariants using quantifier-elimination is proposed. An invariant of a loop is hypothesized as a parameterized formula. Parameters in the invariant are discovered by generating constraints on the parameters by ensuring that the formula is indeed

verification reduces to solving such clauses. In this paper we present a method for solving forall-exists quantified Horn clauses extended with well-foundedness conditions. Our method is based on a counterexample-guided abstraction refinement scheme to discover witnesses for existentially quantified variables