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Formal Methods in System Design

, Volume 6, Issue 2, pp 147–189 | Cite as

Formal verification by symbolic evaluation of partially-ordered trajectories

  • Carl-Johan H. Seger
  • Randal E. Bryant
Article

Abstract

Symbolic trajectory evaluation provides a means to formally verify properties of a sequential system by a modified form of symbolic simulation. The desired system properties are expressed in a notation combining Boolean expressions and the temporal logic “next-time” operator. In its simplest form, each property is expressed as an assertion [A⇒C], where the antecedentA expresses some assumed conditions on the system state over a bounded time period, and the consequentC expresses conditions that should result. A generalization allows simple invariants to be established and proven automatically.

The verifier operates on system models in which the state space is ordered by “information content”. By suitable restrictions to the specification notation, we guarantee that for every trajectory formula, there is a unique weakest state trajectory that satisfies it. Therefore, we can verify an assertion [A⇒C] by simulating the system over the weakest trajectory forA and testing adherence toC. Also, establishing invariants correspond to simple fixed point calculations.

This paper presents the general theory underlying symbolic trajectory evaluation. It also illustrates the application of the theory to the taks of verifying switch-level circuits as well as more abstract implementations.

Keywords

Temporal Logic System Property Point Calculation State Trajectory Sequential System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Carl-Johan H. Seger
    • 1
  • Randal E. Bryant
    • 2
  1. 1.Department of Computer ScienceUniversity of British ColumbiaVancouverCanada
  2. 2.School of Computer ScienceCarnegie Mellon UniversityPittsburghUSA

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