In this paper we consider the problem of verifying trace-based information flow properties for different classes of system models. We begin by proposing an automata-theoretic technique for model-checking trace-based information flow properties for finite-state systems. We do this by showing that Mantel's Basic Security Predicates (BSPs), which were shown to be the building blocks of most trace-based properties in the literature, can be verified in an automated way for finite-state system models. We also consider the problem for the class of pushdown system models, and show that it is undecidable to check such systems for any of the trace-based information flow properties. Finally we consider a simple trace-based property we call "weak non-inference" and show that it is undecidable even for finite-state systems.

We present an automated verification technique to verify trace based information flow properties for finite state systems. We show that the Basic Security Predicates (BSPs) defined by Mantel in [5], which are shown to be the building blocks of known trace based information flow properties, can be characterised in terms of regularity preserving language theoretic operations. This leads to a decision procedure for checking whether a finite state system satisfies a given BSP. Verification techniques in the literature (e.g. unwinding) are based on the structure of the transition system and are incomplete in some cases. In contrast, our technique is language based and complete for all information flow properties that can be expressed in terms of BSPs.

No abstract

Background: Sweet's syndrome (SS) is a classical representative of neutrophilic dermatosis characterized by the abrupt onset of fever, erythematous tender plaques and nodules on exposed parts, and histopathological reaction in response to different external and internal stimuli. Objectives: The aim of this study was to assess the clinical, epidemiological, histological features and therapeutic outcomes of SS. Materials and Methods: A retrospective study of all patients diagnosed with SS over a 4-year period (2016–2020) was conducted. Results: Over a period of 4 years, a total number of cases of SS were 16. Female patients were predominant around 13 (81.25%), and male patients were 3 (18.75%). The most common site affected was face in 87.5% (14), followed by upper limb in 50% (8) and lower limb in 25% (4). Among the systemic manifestations, fever was there in all cases. The associated causes were infectious conditions in 6 (37.5%) cases, among which five cases were upper respiratory tract infection, hematological malignancy in three cases, one case with solid tumors, one case was associated with acquired cutis laxa (Marshall' s syndrome), one was drug induced (diclofenac sodium), one case was pregnancy associated, and other three cases were idiopathic. Conclusion: SS can be diagnosed based on clinical and laboratory findings. In all atypical and recurrent SS cases, thorough evaluation for malignancy is essential. Dapsone can be considered a concomitant therapy along with steroids and also a steroid-sparing agent.

Abstract. Bisimulation-based information flow properties were introduced by Focardi and Gorrieri [6] as a way of specifying security properties for transition system models. These properties were shown to be decidable for finite-state systems. In this paper, we study the problem of verifying these properties for some well-known classes of infinite state systems. We show that all the properties are undecidable for each of these classes of systems.