Logarithmic Approximation for Road Pricing on Grids

Fuente: arXiv
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Autori principali: Constantinescu, Andrei, Turko, Andrzej, Wattenhofer, Roger
Natura: Preprint
Pubblicazione: 2025
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author Constantinescu, Andrei
Turko, Andrzej
Wattenhofer, Roger
author_facet Constantinescu, Andrei
Turko, Andrzej
Wattenhofer, Roger
contents Consider a graph $G = (V, E)$ and some commuters, each specified by a tuple $(u, v, b)$ consisting of two nodes in the graph $u, v \in V$ and a non-negative real number $b$, specifying their budget. The goal is to find a pricing function $p$ of the edges of $G$ that maximizes the revenue generated by the commuters. Here, each commuter $(u, v, b)$ either pays the lowest-cost of a $u$-$v$ path under the pricing $p$, or 0, if this exceeds their budget $b$. We study this problem for the case where $G$ is a bounded-width grid graph and give a polynomial-time approximation algorithm with approximation ratio $O(\log |E|)$. Our approach combines existing ideas with new insights. Most notably, we employ a rather seldom-encountered technique that we coin under the name 'assume-implement dynamic programming.' This technique involves dynamic programming where some information about the future decisions of the dynamic program is guessed in advance and 'assumed' to hold, and then subsequent decisions are forced to 'implement' the guess. This enables computing the cost of the current transition by using information that would normally only be available in the future.
format Preprint
id arxiv_https___arxiv_org_abs_2502_11979
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Logarithmic Approximation for Road Pricing on Grids
Constantinescu, Andrei
Turko, Andrzej
Wattenhofer, Roger
Data Structures and Algorithms
Computer Science and Game Theory
Consider a graph $G = (V, E)$ and some commuters, each specified by a tuple $(u, v, b)$ consisting of two nodes in the graph $u, v \in V$ and a non-negative real number $b$, specifying their budget. The goal is to find a pricing function $p$ of the edges of $G$ that maximizes the revenue generated by the commuters. Here, each commuter $(u, v, b)$ either pays the lowest-cost of a $u$-$v$ path under the pricing $p$, or 0, if this exceeds their budget $b$. We study this problem for the case where $G$ is a bounded-width grid graph and give a polynomial-time approximation algorithm with approximation ratio $O(\log |E|)$. Our approach combines existing ideas with new insights. Most notably, we employ a rather seldom-encountered technique that we coin under the name 'assume-implement dynamic programming.' This technique involves dynamic programming where some information about the future decisions of the dynamic program is guessed in advance and 'assumed' to hold, and then subsequent decisions are forced to 'implement' the guess. This enables computing the cost of the current transition by using information that would normally only be available in the future.
title Logarithmic Approximation for Road Pricing on Grids
topic Data Structures and Algorithms
Computer Science and Game Theory
url https://arxiv.org/abs/2502.11979