Approximation Algorithms for Route Planning with Nonlinear Objectives

TL;DR

This paper develops approximation algorithms for complex route planning problems involving nonlinear, non-monotonic objectives, enabling efficient near-optimal solutions under certain constraints, with applications to time-sensitive routing.

Contribution

It introduces a fully polynomial approximation scheme for nonlinear route planning with hop constraints, extending to pseudo-polynomial time under linear constraints, addressing a challenging NP-hard problem.

Findings

Efficient approximation algorithms for nonlinear, non-monotonic route planning.

Extension of algorithms to pseudo-polynomial time under linear constraints.

Application of algorithms to time-on-time path problems.

Abstract

We consider optimal route planning when the objective function is a general nonlinear and non-monotonic function. Such an objective models user behavior more accurately, for example, when a user is risk-averse, or the utility function needs to capture a penalty for early arrival. It is known that as nonlinearity arises, the problem becomes NP-hard and little is known about computing optimal solutions when in addition there is no monotonicity guarantee. We show that an approximately optimal non-simple path can be efficiently computed under some natural constraints. In particular, we provide a fully polynomial approximation scheme under hop constraints. Our approximation algorithm can extend to run in pseudo-polynomial time under a more general linear constraint that sometimes is useful. As a by-product, we show that our algorithm can be applied to the problem of finding a path that is most likely to be on time for a given deadline.