Bounded Depth-First Search

Depth-first search can spend much time (perhaps infinite time) exploring a very deep path that does not contain a solution, when a shallow solution exists.

An easy way to solve this problem is to put a maximum depth bound on the search. Beyond the depth bound , a failure is generated automatically without exploring any deeper.

Problems:

1. It's hard to guess how deep the solution lies.

2. If the estimated depth is too deep (even by 1) the computer time used is significantly increased, by a factor of b^extra.

3. If the estimated depth is too shallow, the search fails to find a solution; all that computer time is wasted.