Online Selection with Uncertain Disruption

TL;DR

This paper introduces the OS-UD problem, addressing online resource allocation under uncertain disruptions, and proposes algorithms with optimal competitive ratios for maximizing expected value in such scenarios.

Contribution

It formulates the novel OS-UD problem and develops threshold-based online algorithms with proven optimal competitive ratios under uncertainty.

Findings

Single-threshold algorithm achieves a competitive ratio of at least 1-1/e.

Adaptive threshold algorithm attains an asymptotic ratio of at least 0.745.

Both algorithms are worst-case optimal within their classes.

Abstract

In numerous online selection problems, decision-makers (DMs) must allocate on the fly limited resources to customers with uncertain values. The DM faces the tension between allocating resources to currently observed values and saving them for potentially better, unobserved values in the future. Addressing this tension becomes more demanding if an uncertain disruption occurs while serving customers. Without any disruption, the DM gets access to the capacity information to serve customers throughout the time horizon. However, with uncertain disruption, the DM must act more cautiously due to risk of running out of capacity abruptly or misusing the resources. Motivated by this tension, we introduce the Online Selection with Uncertain Disruption (OS-UD) problem. In OS-UD, a DM sequentially observes n non-negative values drawn from a common distribution and must commit to select or reject each value in real time, without revisiting past values. The disruption is modeled as a Bernoulli random variable with probability p each time DM selects a value. We aim to design an online algorithm that maximizes the expected sum of selected values before a disruption occurs, if any. We evaluate online algorithms using the competitive ratio. Using a quantile-based approach, we devise a non-adaptive single-threshold algorithm that attains a competitive ratio of at least 1-1/e, and an adaptive threshold algorithm characterized by a sequence of non-increasing thresholds that attains an asymptotic competitive ratio of at least 0.745. Both of these results are worst-case optimal within their corresponding class of algorithms.