Fast Query Answering by Labeling Index on Uncertain Graphs

Given the ubiquity of Uncertain Graphs (UGs), the field of UG mining has garnered increasing attention. Among various mining tasks, query processing stands out as the most fundamental and crucial. Current methods for query answering on UGs primarily rely on Monte-Carlo sampling and heuristic approaches. However, these techniques either struggle with a significant efficiency-accuracy trade-off or lack generalization over different graphs and queries. To circumvent these limitations, this work proposes a novel index-based method for query answering on UGs. We construct a labeling index framework, which can answer queries by pre-computed and stored operators. To the best of our knowledge, this is the first index frame-work that can deal with reliability, expected reliable distance and distance-constrained reliability queries, providing lower or upper bounded query answer results. By transferring the time consuming sampling process into the offline index operator computation, the query answering only needs to traverse a limited number of operators, which accelerates the response time of query answering with several orders of magnitude. We further utilize the vertex cover and its h-hop extension to prune the index structure, thereby reducing the space complexity. Experimental results on five real-world datasets demonstrate that the proposed index framework is both effective and efficient.

I. Introduction

Uncertain graphs (UGs) represent a specific type of graph wherein the existence of each edge is associated with a specific probability [1], [2]. UGs find extensive application in numerous real-world scenarios. For instance, in social network analyses, the influence between socially-connected users is often modeled using an influence probability [3]; in bioinformatics, interactions between proteins are frequently depicted with an uncertain model [4].