TY - GEN
T1 - A* with Lookahead Re-Evaluated
AU - Bu, Zhaoxing
AU - Stern, Roni
AU - Felner, Ariel
AU - Holte, Robert C.
N1 - Publisher Copyright:
Copyright © 2014, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved.
PY - 2014/1/1
Y1 - 2014/1/1
N2 - A* with lookahead (AL*) is a variant of A* that performs a cost-bounded DFS lookahead from a node when it is generated. We show that the original version of AL* (AL∗ 0) can, in some circumstances, fail to return an optimal solution because of the move pruning it does. We present two new versions, AL∗ 1 and ELH, that we prove to always be correct and give conditions in which AL∗ 0 is guaranteed to be correct. In our experiments with unit costs, AL∗ 0 was usually the fastest AL* version, but its advantage was usually small. In our experiments with non-unit costs, AL∗ 0 substantially outperforms both A* and IDA*. We also evaluate the idea of immediately expanding a generated node if it has the same f-value as its parent. We find that doing so causes AL* to require more memory and sometimes slows AL* down.
AB - A* with lookahead (AL*) is a variant of A* that performs a cost-bounded DFS lookahead from a node when it is generated. We show that the original version of AL* (AL∗ 0) can, in some circumstances, fail to return an optimal solution because of the move pruning it does. We present two new versions, AL∗ 1 and ELH, that we prove to always be correct and give conditions in which AL∗ 0 is guaranteed to be correct. In our experiments with unit costs, AL∗ 0 was usually the fastest AL* version, but its advantage was usually small. In our experiments with non-unit costs, AL∗ 0 substantially outperforms both A* and IDA*. We also evaluate the idea of immediately expanding a generated node if it has the same f-value as its parent. We find that doing so causes AL* to require more memory and sometimes slows AL* down.
UR - http://www.scopus.com/inward/record.url?scp=85007246977&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:85007246977
T3 - Proceedings of the 7th Annual Symposium on Combinatorial Search, SoCS 2014
SP - 44
EP - 52
BT - Proceedings of the 7th Annual Symposium on Combinatorial Search, SoCS 2014
A2 - Edelkamp, Stefan
A2 - Bartak, Roman
PB - AAAI press
T2 - 7th Annual Symposium on Combinatorial Search, SoCS 2014
Y2 - 15 August 2014 through 17 August 2014
ER -