A Framework for State and Trace Interpolation

We address the problem of reasoning about interleavings in safety verification of concurrent processes. In the literature, there are two prominent techniques for pruning the search space. First, there is state-based interpolation where a collection of formulas can be generalized by taking into account the property to be verified. Second, there are trace-based methods, collectively known as “Partial Order Reduction”, which operate by weakening the concept of a trace by abstracting the total order in the trace into a partial order. We first contribute by further weakening the concept of Partial Order Reduction to Trace Interpolation, in order to adapt it for a symbolic execution framework with abstraction. The main contribution of this paper, however, is a framework that synergistically combines state and trace interpolation so that the sum is more than its parts.