Nested Search versus Limited Discrepancy Search

TL;DR

This paper compares Nested Search and Limited Discrepancy Search, arguing that following the best heuristic playout as in NS often yields better search efficiency than LDS, which emphasizes the best heuristic move.

Contribution

The paper provides a comparative analysis of NS and LDS, highlighting the advantages of NS in focusing on the best heuristic playout for improved search performance.

Findings

NS spends more time on the best heuristic playout

LDS emphasizes the best heuristic move

Following the best heuristic playout can be more effective

Abstract

Limited Discrepancy Search (LDS) is a popular algorithm to search a state space with a heuristic to order the possible actions. Nested Search (NS) is another algorithm to search a state space with the same heuristic. NS spends more time on the move associated to the best heuristic playout while LDS spends more time on the best heuristic move. They both use similar times for the same level of search. We advocate in this paper that it is often better to follow the best heuristic playout as in NS than to follow the heuristic as in LDS.