2. 2
8 puzzle problem
What is 8 puzzle Problem?
The 8-puzzle problem is a puzzle invented and popularized by
Noyes Palmer Chapman in the 1870s. It is played on a 3-by-3
grid with 8 square blocks labeled 1 through 8 and a blank
square.
4. Before we talk about the A* algorithm, we need to discussHeuristic Search
A Heuristic is a technique to
solve a problem faster than
classic methods, or to find an
approximate solution when
classic methods cannot. This is
a kind of a shortcut as we
often trade one of optimality,
completeness, accuracy, or
precision for speed.
5. How it works?
1. A* Algorithm maintains a tree of
paths originating at the initial state.
2. It extends those paths one edge at a
time.
3. It continues until final state is
reached.
11. Pros
&
Cons
Pros:
It is complete and optimal.
It is the best one from other techniques. It is used to solve very complex problems.
It is optimally efficient, i.e. there is no other optimal algorithm guaranteed to expand fewer nodes than A*.
Cons:
This algorithm is complete if the branching factor is finite and every action has fixed cost.
The speed execution of A* search is highly dependent on the accuracy of the heuristic algorithm that is used to compute h (n).
It has complexity problems.
12. Important Note
A* Algorithm
is one of the
best path
finding
algorithms.
.
But it does
not
produce the
shortest
path
always.
This is
because it
heavily
depends on
heuristics.