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...ing solver. Hampi’s source code, documentation, and the experimental data are available at http://people.csail.mit. edu/akiezun/hampi. 1. INTRODUCTION Many automatic testing [7, 20, 36, 42], analysis =-=[22]-=-, and verification [9, 10] techniques for programs can be effectively reduced to a constraint-generation phase followed by a constraint-solving phase. This separation of concerns often leads to more e...

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...t only for linear systems, using interesting techniques [28, 29]. In software program analysis, constraint based techniques have been successfully applied for discovering linear arithmetic invariants =-=[7, 21, 23, 10]-=-, non-linear polynomial invariants [12] and invariants in the combined theory of linear arithmetic and uninterpreted functions [4]. 7 Conclusion The verification technique based on guessing the form o...

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...ms which the tool needs to search in order to find one that is equivalent to the reference implementation and that requires minimum number of corrections. We use constraint-based synthesis technology =-=[16, 37, 40]-=- to efficiently search over this large space of programs. Specifically, we use the SKETCH synthesizer that uses a SAT-based algorithm to complete program sketches (programs with holes) so that they me...

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...uired two iterations.6 Related Work Constraint-based techniques have been recently used for discovering linear arithmetic invariants (conjunctive invariants [12–15] as well as disjunctive invariants =-=[16]-=- in the context of verifying safety properties as well as discovering ranking functions for proving termination [17, 18]). Constraint-based techniques have also been applied for discovering non-linear...

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...purious counterexamples produced by model checking to dynamically discover new predicates that serve as building blocks for the proof of program correctness. Finally, in the constraint-based approach =-=[5,14,27]-=-, a parametric representation of an invariant map serves a starting point. Then, inductiveness and safety conditions are encoded as constraints on the parameters. Once these constraints have been dete...

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...for concurrent programs than conditional termination. Related work Until now few papers have directly addressed the problem of automatically underapproximating weakest preconditions. One exception is =-=[18]-=-, which yields constraint systems that are non-linear. The constraint-based technique in [9] could also be modified to find preconditions, but again at the cost of non-linear constraints. The synthesi...

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... was recently introduced by Vechev, Yahav and Yorsh [31], as a follow up to earlier work on synthesis of concurrent datastructures [30]. Their system is designed to synthesize efficient synchronization for concurrent programs, and is very different from ours, both in its scope and in the algorithms it uses. Unlike their system, our synthesizer is based on a more general constraint-based approach that allows us to handle extremely large search spaces with no apparent structure. The idea of using a constraint-based approach for abstract interpretation was previously introduced by Gulwani et al. [10]. Recently, their group has used similar techniques to synthesize invariants [11] and even complete programs [29]. Some important distinctions between their work and ours are the use of storyboards to capture insights, as well as our path-based representation of the constraints to support a very large and complex abstract domain. The idea of using a sketch to define the structure of the implementation was adapted from the original work on sketch based synthesis [25]. The idea was originally applied to the domain of bit-stream manipulations [27], such as ciphers and error correction codes, and ...