Bidirectional search algorithms interleave two separate searches, a normal search forward
from the start state, and a search backward from the goal. It is well known that adding a …

We present MM, the first bidirectional heuristic search algorithm whose forward and
backward searches are guaranteed to''meet in the middle'', ie never expand a node beyond …

The assessment of bidirectional heuristic search has been incorrect since it was first
published more than a quarter of a century ago. For quite a long time, this search strategy …

We present an intuitive explanation for the limited effectiveness of front-to-end bidirectional
heuristic search, supported with extensive evidence from many commonly-studied domains …

Recent work in bidirectional heuristic search characterize pairs of nodes from which at least
one node must be expanded in order to ensure optimality of solutions. We use these …

Recently there has been renewed interest in bidirectional heuristic search. New algorithms,
eg, MM, MMe, and NBS, have been introduced which seem much closer to refuting the …

In the past few years, new very successful bidirectional heuristic search algorithms have
been proposed. Their key novelty is a lower bound on the cost of a solution that includes …

It is well-known that any admissible unidirectional heuristic search algorithm must expand all
states whose $ f $-value is smaller than the optimal solution cost when using a consistent …

A* is optimal among admissible unidirectional algorithms when searching with a consistent
heuristic. Recently, similar optimality bounds have been established for bidirectional search …

Recently, we showed that for traditional bidirectional search with" front-to-end" evaluations, it
is not the meeting of search fronts but the cost of proving the optimality of a solution that is …