Provenance Circuits for Trees and Treelike Instances (Extended Version)

TL;DR

This paper introduces a linear-time method to construct provenance circuits for MSO queries on trees and treelike instances, connecting automata-based provenance with semiring frameworks and enabling applications in counting and probabilistic query evaluation.

Contribution

It presents a novel linear-time construction of provenance circuits for MSO queries on trees, bridging automata-based and semiring provenance frameworks.

Findings

Provenance circuits can be constructed in linear time for MSO queries on trees.

The framework connects automata-based provenance with semiring provenance.

Applications include improved counting and probabilistic query evaluation.

Abstract

Query evaluation in monadic second-order logic (MSO) is tractable on trees and treelike instances, even though it is hard for arbitrary instances. This tractability result has been extended to several tasks related to query evaluation, such as counting query results [3] or performing query evaluation on probabilistic trees [10]. These are two examples of the more general problem of computing augmented query output, that is referred to as provenance. This article presents a provenance framework for trees and treelike instances, by describing a linear-time construction of a circuit provenance representation for MSO queries. We show how this provenance can be connected to the usual definitions of semiring provenance on relational instances [20], even though we compute it in an unusual way, using tree automata; we do so via intrinsic definitions of provenance for general semirings, independent of the operational details of query evaluation. We show applications of this provenance to capture existing counting and probabilistic results on trees and treelike instances, and give novel consequences for probability evaluation.