arXiv subjects

Lucas Peña

Publications and source records attributed to Lucas Peña.

5 recordsLinked to original sources

arXiv2026

Complete first-order reasoning for functional programs

Several practical tools for automatically verifying functional programs (e.g., Liquid Haskell and Leon for Scala programs) rely on a heuristic based on unrolling recursive function definitions followed by quantifier-free reasoning using SMT solvers. We uncover foundational theoretical properties of this heuristic, revealing that it can be generalized and formalized as a technique that is in fact complete for reasoning with combined First-Order theories of algebraic datatypes and background theories, where background theories support decidable quantifier-free reasoning. The theory developed in this paper explains the efficacy of these heuristics when they succeed, explains why they fail when they fail, and the precise role that user help plays in making proofs succeed.

cs.LO↗

arXiv2022

A First-Order Logic with Frames

We propose a novel logic, called Frame Logic (FL), that extends first-order logic (with recursive definitions) using a construct Sp(.) that captures the implicit supports of formulas -- the precise subset of the universe upon which their meaning depends. Using such supports, we formulate proof rules that facilitate frame reasoning elegantly when the underlying model undergoes change. We show that the logic is expressive by capturing several data-structures and also exhibit a translation from a precise fragment of separation logic to frame logic. Finally, we design a program logic based on frame logic for reasoning with programs that dynamically update heaps that facilitates local specifications and frame reasoning. This program logic consists of both localized proof rules as well as rules that derive the weakest tightest preconditions in FL.

cs.LO↗

arXiv2022

Model-Guided Synthesis of Inductive Lemmas for FOL with Least Fixpoints

Recursively defined linked data structures embedded in a pointer-based heap and their properties are naturally expressed in pure first-order logic with least fixpoint definitions (FO+lfp) with background theories. Such logics, unlike pure first-order logic, do not admit even complete procedures. In this paper, we undertake a novel approach for synthesizing inductive hypotheses to prove validity in this logic. The idea is to utilize several kinds of finite first-order models as counterexamples that capture the non-provability and invalidity of formulas to guide the search for inductive hypotheses. We implement our procedures and evaluate them extensively over theorems involving heap data structures that require inductive proofs and demonstrate the effectiveness of our methodology.

cs.LO↗

arXiv2022

Mechanizing Matching Logic In Coq

Matching logic is a formalism for specifying, and reasoning about, mathematical structures, using patterns and pattern matching. Growing in popularity, it has been used to define many logical systems such as separation logic with recursive definitions and linear temporal logic. In addition, it serves as the logical foundation of the K semantic framework, which was used to build practical verifiers for a number of real-world languages. Despite being a fundamental formal system accommodating substantial theories, matching logic lacks a general-purpose, machine-checked formalization. Hence, we formalize matching logic using the Coq proof assistant. Specifically, we create a new representation of matching logic that uses a locally nameless encoding, and we formalize the syntax, semantics, and proof system of this representation in the Coq proof assistant. Crucially, we prove the soundness of the formalized proof system and provide a means to carry out interactive matching logic reasoning in Coq. We believe this work provides a previously unexplored avenue for reasoning about matching logic, its models, and the proof system.

cs.LO↗

arXiv2020

Towards a Verified Model of the Algorand Consensus Protocol in Coq

The Algorand blockchain is a secure and decentralized public ledger based on pure proof of stake rather than proof of work. At its core it is a novel consensus protocol with exactly one block certified in each round: that is, the protocol guarantees that the blockchain does not fork. In this paper, we report on our effort to model and formally verify the Algorand consensus protocol in the Coq proof assistant. Similar to previous consensus protocol verification efforts, we model the protocol as a state transition system and reason over reachable global states. However, in contrast to previous work, our model explicitly incorporates timing issues (e.g., timeouts and network delays) and adversarial actions, reflecting a more realistic environment faced by a public blockchain. Thus far, we have proved asynchronous safety of the protocol: two different blocks cannot be certified in the same round, even when the adversary has complete control of message delivery in the network. We believe that our model is sufficiently general and other relevant properties of the protocol such as liveness can be proved for the same model.

cs.CR↗