William Klieber

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We propose two novel approaches for using CounterexampleGuided Abstraction Refinement (CEGAR) in Quantified Boolean Formula (QBF) solvers. The first approach develops a recursive algorithm whose search is driven by CEGAR (rather than by DPLL). The second approach employs CEGAR as an additional learning technique in an existing DPLL-based QBF solver.(More)
One approach to defending against malicious Android applications has been to analyze them to detect potential information leaks. This paper describes a new static taint analysis for Android that combines and augments the FlowDroid and Epicc analyses to precisely track both inter-component and intra-component data flow in a set of Android applications. The(More)
We describe a DPLL-based solver for the problem of quantified boolean formulas (QBF) in non-prenex, non-CNF form. We make two contributions. First, we reformulate clause/cube learning, extending it to non-prenex instances. We call the resulting technique game-state learning. Second, we introduce a propagation technique using ghost literals that exploits the(More)
Model checking is an automatic verification technique for hardware and software systems that are finite state or have finite state abstractions. It has been used successfully to verify computer hardware, and it is beginning to be used to verify computer software as well. As the number of state variables in the system increases, the size of the system state(More)
An open quantified boolean formula (QBF) is a QBF that contains free (unquantified) variables. A solution to such a QBF is a quantifier-free formula that is logically equivalent to the given QBF. Although most recent QBF research has focused on closed QBF, there are a number of interesting applications that require one to consider formulas with free(More)
In this paper we present and compare primal discontinuous Galerkin formulations of the two-phase flow equations. The wetting phase pressure and saturation equations are decoupled and solved sequentially. Proposed adaptivity in space and time techniques yield accurate and efficient solutions. Slope limiters valid on non-conforming meshes are also presented.(More)