@conference {424,
	title = { PyCHC: a Framework for Certified Horn Solving and CHC-based Design},
	booktitle = {CAV 2026},
	year = {2026},
	abstract = {We present PyCHC, a solver-agnostic framework aimed at systems of constrained Horn clauses (CHC). PyCHC provides intuitive Python APIs to create and manipulate CHC systems programmatically and solve them using different backend solvers. Furthermore, PyCHC offers a certification pipeline to validate the correctness of results reported by the CHC solvers, via the use of independent satisfiability modulo theories (SMT) solvers and proof checkers. We present our framework{\textquoteright}s architecture and features, and demonstrate how it enables rapid prototyping of new CHC-based algorithms and experimentation with novel strategies for cooperative solving. We used PyCHC to validate the results of the Eldarica, Golem, and Spacer solvers on CHC-COMP benchmarks, finding several issues across different tool versions.
},
	author = {Anna Becchi and Martin Blicha and Rodrigo Otoni and Natasha Sharygina}
}
@conference {403,
	title = {Unsatisfiability Proofs for Horn Solving},
	booktitle = {TACAS},
	year = {2025},
	abstract = {Many verification tools currently rely on logic solvers as backend reasoning engines. Despite playing such a pivotal role, bugs are not uncommon in the complex codebases of these solvers. Validating their results is thus critical, with correctness witnesses often being used for this end. Output validation for constrained Horn clauses (CHC) solvers is not a well explored topic though, especially in regards to unsatisfiability results. This is a significant issue, given that CHC solvers are being increasingly employed in verification tooling. To address it, we propose an approach to validate CHC unsatisfiability results based on independently checkable proofs. Our approach is generic in regards to the solving algorithm, preprocessing steps, and exact proof format used, and works by first producing a coarse-grained proof during solving and then instantiating it into a suitable proof format by adding missing details, at which point the instantiated proof can be checked by an independent proof checker. We instrumented a state-of-the-art CHC solver to generate proofs in the Alethe format and performed a large-scale evaluation. Our results indicate that proofs can be produced with minimal overhead, can be efficiently checked, and have tractable sizes.
},
	doi = {10.1007/978-3-031-90653-4_4},
	author = {Rodrigo Otoni and Martin Blicha and Matias Barandiaran Rivera and Patrick Eugster and Jan Kofron and Natasha Sharygina}
}
@conference {383,
	title = {CHC Model Validation with Proof Guarantees},
	booktitle = {18th International Conference on integrated Formal Methods (iFM23)},
	year = {2023},
	url = {https://doi.org/10.1007/978-3-031-47705-8_4},
	author = {Rodrigo Otoni and Martin Blicha and Patrick Eugster and Natasha Sharygina}
}
@conference {375,
	title = {Symbolic Model Checking for TLA+ Made Faster},
	booktitle = {TACAS - 29th International Conference on Tools and Algorithms for the Construction and Analysis of Systems},
	year = {2023},
	address = {Paris},
	url = {https://doi.org/10.1007/978-3-031-30823-9_7},
	author = {Rodrigo Otoni and Igor Konnov and Jure Kukovec and Patrick Eugster and Natasha Sharygina}
}
@article {373,
	title = {A Solicitous Approach to Smart Contract Verification},
	journal = {ACM Transactions on Privacy and Security},
	year = {2022},
	type = {Full-Length Research Paper},
	url = {https://dl.acm.org/doi/10.1145/3564699},
	author = {Rodrigo Otoni and Matteo Marescotti and Leonardo Alt and Patrick Eugster and Antti E. J. Hyv{\"a}rinen and Natasha Sharygina}
}
@conference {334,
	title = {Theory-Specific Proof Steps Witnessing Correctness of SMT Executions},
	booktitle = {DAC 2021 - 58th Design Automation Conference},
	year = {2021},
	month = {11/2021},
	publisher = {IEEE},
	organization = {IEEE},
	address = {San Francisco, CA, USA},
	doi = {10.1109/DAC18074.2021.9586272},
	author = {Rodrigo Otoni and Martin Blicha and Patrick Eugster and Antti E. J. Hyv{\"a}rinen and Natasha Sharygina}
}
@conference {319,
	title = {Accurate Smart Contract Verification through Direct Modelling},
	booktitle = {ISoLA 2020 - 9th International Symposium On Leveraging Applications of Formal Methods, Verification and Validation},
	year = {2020},
	publisher = {Springer International Publishing},
	organization = {Springer International Publishing},
	isbn = {978-3-030-61467-6},
	doi = {doi.org/10.1007/978-3-030-61467-6_12},
	url = {https://link.springer.com/chapter/10.1007\%2F978-3-030-61467-6_12},
	author = {Matteo Marescotti and Rodrigo Otoni and Leonardo Alt and Patrick Eugster and Antti E. J. Hyv{\"a}rinen and Natasha Sharygina}
}
@conference {165,
	title = {PINCETTE - Validating Changes and Upgrades in Networked Software},
	booktitle = {17th European Conference on Software Maintenance and Reengineering},
	year = {2013},
	author = {Chockler, H. and Denaro, G. and Ling, M. and Grigory Fedyukovich and Antti E. J. Hyv{\"a}rinen and Mariani, L. and Muhammad, A. and Oriol, M. and Rajan, A. and Sery, O. and Natasha Sharygina and Tautschnig, M.}
}
