arXiv subjects

Francesca Scozzari

Publications and source records attributed to Francesca Scozzari.

6 recordsLinked to original sources

arXiv2026

Experimental evaluation of optimal abstract operators for sharing and linearity analysis

In the field of static analysis of logic programs, the optimality of abstract operators is a valuable theoretical property, as it provides insight into the structure of abstract domains and the maximum precision that can be achieved. However, implementing optimal operators is often complex and may significantly impact performance, giving rise to a trade-off between precision and efficiency. We experimentally investigate this trade-off in the context of sharing and linearity analysis of logic programs. Our experiments build on previous work that proposed several optimal operators for unification and matching. We have implemented these abstract operators and the corresponding abstract domains within the PLAI analyzer, part of the CiaoPP preprocessor, and we report the impact of increasing operator precision on the accuracy and performance of the overall analysis.

cs.LO↗

arXiv2024

Optimal matching for sharing and linearity analysis

Static analysis of logic programs by abstract interpretation requires designing abstract operators which mimic the concrete ones, such as unification, renaming and projection. In the case of goal-driven analysis, where goal-dependent semantics are used, we also need a backward-unification operator, typically implemented through matching. In this paper we study the problem of deriving optimal abstract matching operators for sharing and linearity properties. We provide an optimal operator for matching in the domain ${\mathtt{ShLin}^ω}$, which can be easily instantiated to derive optimal operators for the domains ${\mathtt{ShLin}^{2}}$ by Andy King and the reduced product $\mathtt{Sharing} \times \mathtt{Lin}$.

cs.PL↗

arXiv2015

Efficiently intertwining widening and narrowing

Non-trivial analysis problems require posets with infinite ascending and descending chains. In order to compute reasonably precise post-fixpoints of the resulting systems of equations, Cousot and Cousot have suggested accelerated fixpoint iteration by means of widening and narrowing. The strict separation into phases, however, may unnecessarily give up precision that cannot be recovered later, as over-approximated interim results have to be fully propagated through the equation the system. Additionally, classical two-phased approach is not suitable for equation systems with infinitely many unknowns---where demand driven solving must be used. Construction of an intertwined approach must be able to answer when it is safe to apply narrowing---or when widening must be applied. In general, this is a difficult problem. In case the right-hand sides of equations are monotonic, however, we can always apply narrowing whenever we have reached a post-fixpoint for an equation. The assumption of monotonicity, though, is not met in presence of widening. It is also not met by equation systems corresponding to context-sensitive inter-procedural analysis, possibly combining context-sensitive analysis of local information with flow-insensitive analysis of globals. As a remedy, we present a novel operator that combines a given widening operator with a given narrowing operator. We present adapted versions of round-robin as well as of worklist iteration, local and side-effecting solving algorithms for the combined operator and prove that the resulting solvers always return sound results and are guaranteed to terminate for monotonic systems whenever only finitely many unknowns (constraint variables) are encountered. Practical remedies are proposed for termination in the non-monotonic case.

cs.PL↗

arXiv2013

Optimal multi-binding unification for sharing and linearity analysis

In the analysis of logic programs, abstract domains for detecting sharing properties are widely used. Recently the new domain $\Linp$ has been introduced to generalize both sharing and linearity information. This domain is endowed with an optimal abstract operator for single-binding unification. The authors claim that the repeated application of this operator is also optimal for multi-binding unification. This is the proof of such a claim.

cs.PL↗

arXiv2009

On the interaction between sharing and linearity

In the analysis of logic programs, abstract domains for detecting sharing and linearity information are widely used. Devising abstract unification algorithms for such domains has proved to be rather hard. At the moment, the available algorithms are correct but not optimal, i.e., they cannot fully exploit the information conveyed by the abstract domains. In this paper, we define a new (infinite) domain ShLin-w which can be thought of as a general framework from which other domains can be easily derived by abstraction. ShLin-w makes the interaction between sharing and linearity explicit. We provide a constructive characterization of the optimal abstract unification operator on ShLin-w and we lift it to two well-known abstractions of ShLin-w. Namely, to the classical Sharing X Lin abstract domain and to the more precise ShLin-2 abstract domain by Andy King. In the case of single binding substitutions, we obtain optimal abstract unification algorithms for such domains. To appear in Theory and Practice of Logic Programming (TPLP).

cs.PL↗

arXiv2009

Optimality in Goal-Dependent Analysis of Sharing

We face the problems of correctness, optimality and precision for the static analysis of logic programs, using the theory of abstract interpretation. We propose a framework with a denotational, goal-dependent semantics equipped with two unification operators for forward unification (calling a procedure) and backward unification (returning from a procedure). The latter is implemented through a matching operation. Our proposal clarifies and unifies many different frameworks and ideas on static analysis of logic programming in a single, formal setting. On the abstract side, we focus on the domain Sharing by Jacobs and Langen and provide the best correct approximation of all the primitive semantic operators, namely, projection, renaming, forward and backward unification. We show that the abstract unification operators are strictly more precise than those in the literature defined over the same abstract domain. In some cases, our operators are more precise than those developed for more complex domains involving linearity and freeness. To appear in Theory and Practice of Logic Programming (TPLP)

cs.PL↗