Computing Shortest Paths Using A*, Landmarks, and Polygon Inequalities (Abstract)

We introduce a new dual-landmark heuristic for the A* algorithm that references a data structure of size θ(|L| + |V |), where L represents a set of strategically chosen landmark vertices and V the set of vertices in the graph. This heuristic’s benefits are permitted by a new approach for computing lower bounds based on generalized polygon inequalities, in which each landmark stores the distances between it and vertices within its graph partition. In this paper, we demonstrate experimental results that show exemplify the space complexity reduction and speedup in comparison to its single-landmark counterpart for large graphs.