Global Search: A global search algorithm works
by looking for an optimal solution in the complete graph. This can
be differentiated from a local search which just looks for an
optimal solution in a small part of the graph. For example the
Dijkstra's Algorithm is a global search while the Beam Search is a
local search algorithm.
Problems of Global Searches:
Here are some problems associated with global searches:
- Slow: A global search is much slower than a
local search as it has to look for the optimal solution in the
complete graph of choices. Further it has to take action based on a
huge lot of choices at all steps. This makes the algorithm
slow.
- Huge Memory Requirement: A global search has
to keep in its frontier all the nodes that are candidates to an
optimal solution. Since it has to look at the complete graph for
the optimal solution, the frontier becomes a large set. This set
has to be stored in memory (RAM) and requires a lot of memory for
storage.
- Repeated States in Search: If the search is
such that the states may be repeated, the algorithm may get stuck
and may not be able to complete the entire graph.
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