Sokolsky, Oleg

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Computer Sciences
Software Engineering
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Research Professor
Introduction
My main research interest is the application of formal methods to design and verification of cyber-physical systems. Other interests, all related to the main one, include on-line monitoring of embedded systems and formal foundations for it, hybrid systems, automated extraction of specifications from source code, and formal methods in software engineering in general and in embedded software in particular.
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Now showing 1 - 10 of 171
  • Publication
    Generic Infusion Pump Hazard Analysis and Safety Requirements Version 1.0
    (2009-02-06) Arney, David E.; Jetley, Raoul; Lee, Insup; Jones, Paul; Sokolsky, Oleg; Ray, Arnab; Zhang, Yi
    The Generic Infusion Pump (or GIP) project is an effort to make generic formal models of infusion pump systems. Our process of building these formal models started with requirements elicitation and hazard analysis. This document contains the informal requirements and hazard analysis used to create a generic pump model. We plan to use these models and properties to generate tests which can be used for conformance testing infusion pump implementations. Our future work will focus on extending these pump models with additional safety requirements and exploring the use of test generation for conformance testing real pump implementations.
  • Publication
    R-Charon, a Modeling Language for Reconfigurable Hybrid Systems
    (2006-03-29) Sokolsky, Oleg; Pappas, George; Kratz, Fabian; Lee, Insup
    This paper describes the modeling language as an extension for architectural reconfiguration to the existing distributed hybrid system modeling language Charon. The target application domain of R-Charon includes but is not limited to modular reconfigurable robots and large-scale transportation systems. While largely leaving the Charon syntax and semantics intact, R-Charon allows dynamic creation and destruction of components (agents) as well as of links (references) between the agents. As such, R-Charon is the first formal, hybrid automata based modeling language which also addresses dynamic reconfiguration. We develop and present the syntax and operational semantics for R-Charon on three levels: behavior (modes), structure (agents) and configuration (system).
  • Publication
    QuanTM: A Quantitative Trust Management System
    (2009-03-01) West, Andrew G; Aviv, Adam J; Chang, Jian; Prabhu, Vinayak S; Blaze, Matthew A; Kannan, Sampath; Lee, Insup; Smith, Jonathan M; Sokolsky, Oleg
    Quantitative Trust Management (QTM) provides a dynamic interpretation of authorization policies for access control decisions based on upon evolving reputations of the entities involved. QuanTM, a QTM system, selectively combines elements from trust management and reputation management to create a novel method for policy evaluation. Trust management, while effective in managing access with delegated credentials (as in PolicyMaker and KeyNote), needs greater flexibility in handling situations of partial trust. Reputation management provides a means to quantify trust, but lacks delegation and policy enforcement. This paper reports on QuanTM’s design decisions and novel policy evaluation procedure. A representation of quantified trust relationships, the trust dependency graph, and a sample QuanTM application specific to the KeyNote trust management language, are also proposed.
  • Publication
    A Compositional Framework for Avionics (ARINC-653) Systems
    (2009-01-01) Lee, Insup; Easwaran, Arvind; Sokolsky, Oleg; Vestal, Steve
    Cyber-physical systems (CPSs) are becoming all-pervasive, and due to increasing complexity they are designed using component-based approaches. Temporal constraints of such complex CPSs can then be modeled using hierarchical scheduling frameworks. In this paper, we consider one such avionics CPS described by ARINC specification 653-2. The real-time workload in this system comprises of partitions, where each partition consists of one or more processes. Processes incur blocking and preemption overheads, and can communicate with other processes in the system. In this work, we develop techniques for automated scheduling of such partitions. At present, system designers manually schedule partitions based on interactions they have with application vendors. This approach is not only time consuming, but can also result in under utilization of resources. Hence, in this work we propose compositional analysis based scheduling techniques for partitions.
  • Publication
    Process Algebraic Modeling and Analysis of Power-Aware Real-Time Systems
    (2002-08-01) Lee, Insup; Sokolsky, Oleg; Philippou, Anna
    The paper describes a unified formal framework for designing and reasoning about power-constrained, real-time systems. The framework is based on process algebra, a formalism which has been developed to describe and analyze communicating, concurrent systems. The proposed extension allows the modeling of probabilistic resource failures, priorities of resource usages, and power consumption by resources within the same formalism. Thus, it is possible to evaluate alternative power-consumption behaviors and tradeoffs under different real-time schedulers, resource limitations, resource failure probabilities, etc. This paper describes the modeling and analysis techniques, and illustrates them with examples, including a dynamic voltage-scaling algorithm.
  • Publication
    Schedulability Analysis of AADL models
    (2006-04-29) Sokolsky, Oleg; Lee, Insup; Clark, Duncan
    The paper discusses the use of formal methods for the analysis of architectural models expressed in the modeling language AADL. AADL describes the system as a collection of interacting components. The AADL standard prescribes semantics for the thread components and rules of interaction between threads and other components in the system. We present a semantics-preserving translation of AADL models into the real-time process algebra ACSR, allowing us to perform schedulability analysis of AADL models.
  • Publication
    Towards Synthesis of Platform-Aware Attack-Resilient Control Systems: Extended Abstract
    (2013-04-09) Pajic, Miroslav; Bezzo, Nicola; Weimer, James; Alur, Rajeev; Mangharam, Rahul; Michael, Nathan; Pappas, George J; Sokolsky, Oleg; Tabuada, Paulo; Weirich, Stephanie; Lee, Insup
  • Publication
    Compositional Modeling for Refinement for Heirarchical Hybrid Systems
    (2006-07-01) Alur, Rajeev; Lee, Insup; Sokolsky, Oleg; Grosu, Radu
    In this paper,we develop a theory of modular design and refinement of hierarchical hybrid systems. In particular, we present compositional trace-based semantics for the language CHARON that allows modular specification of interacting hybrid systems. For hierarchical description of the system architecture, CHARON supports building complex agents via the operations of instantiation, hiding, and parallel composition. For hierarchical description of the behavior of atomic components, CHARON supports building complex modes via the operations of instantiation, scoping, and encapsulation. We develop an observational trace semantics for agents as well as for modes, and define a notion of refinement for both, based on trace inclusion. We show this semantics to be compositional with respect to the constructs in the language.
  • Publication
    A Modal Specification Approach for On-Demand Medical Systems
    (2013-08-21) King, Andrew L.; Sokolsky, Oleg; Lee, Insup; Feng, Lu
    The on-demand approach, where systems are assembled from components by lay users, has seen success in the consumer electronics industry. Currently, there is growing demand for on-demand capabilities in medical systems so caregivers can create larger medical systems from smaller medical devices. Unlike consumer electronics, medical systems pose challenges for the on-demand approach due to attributes such as device complexity, device variability and safety requirements. In this paper, we propose a formal specification language for on-demand (medical) systems. Our approach is based on the formalism of Modal I/O Automata, which allows system designers to express complex device requirements and can be used to reason about safety and liveness properties of on-demand medical systems directly from their specifications. We illustrate the applicability of our approach through a case study of a closed-loop patient controlled analgesia system.
  • Publication
    On Effective Testing of Health Care Simulation Software
    (2011-01-01) Murphy, Christian; Raunak, M. S.; King, Andrew; Chen, Sanjian; Imbraino, Christopher; Lee, Insup; Kaiser, Gail; Sokolsky, Oleg; Clarke, Lori; Osterweil, Leon
    Health care professionals rely on software to simulate anatomical and physiological elements of the human body for purposes of training, prototyping, and decision making. Software can also be used to simulate medical processes and protocols to measure cost effectiveness and resource utilization. Whereas much of the software engineering research into simulation software focuses on validation (determining that the simulation accurately models real-world activity), to date there has been little investigation into the testing of simulation software itself, that is, the ability to effectively search for errors in the implementation. This is particularly challenging because often there is no test oracle to indicate whether the results of the simulation are correct. In this paper, we present an approach to systematically testing simulation software in the absence of test oracles, and evaluate the effectiveness of the technique.