Online List Access with Precedence Constraints

TL;DR

This paper introduces constant-competitive online algorithms for list access problems with precedence constraints, extending classic algorithms to handle dependencies, motivated by packet classification applications.

Contribution

It develops deterministic and randomized algorithms with constant competitiveness for the generalized list access problem with precedence constraints, using a novel Move-Recursively-Forward procedure.

Findings

Algorithms achieve constant competitiveness.

The approach generalizes Move-To-Front for dependencies.

Addresses challenges of insertions and deletions.

Abstract

This paper considers a natural generalization of the online list access problem in the paid exchange model, where additionally there can be precedence constraints ("dependencies") among the nodes in the list. For example, this generalization is motivated by applications in the context of packet classification. Our main contributions are constant-competitive deterministic and randomized online algorithms, designed around a procedure Move-Recursively-Forward, a generalization of Move-To-Front tailored to handle node dependencies. Parts of the analysis build upon ideas of the classic online algorithms Move-To-Front and BIT, and address the challenges of the extended model. We further discuss the challenges related to insertions and deletions.