Semester7

Notes of courses done/attended in semester 7 in college

Evaluation function f(n) = h(n) (heuristic)
- = estimate of cost from n to goal
eg hSLD(n) = straight-line distance from n to Bucharest
Greedy best first search expands the node that appears to be closest to goal
at the goal node, heuristic fn ki value is 0 (woh best node hai jaha se I can reach goal node)

any heuristics designed should be admissible
for every node n, h(n) <= h(n), h is true cost to reach goal state from n
it never overestimates the cost to reach the goal, i.e. it is optimistic
eg: hsld(n) never overestimates the actual road distance
thm: if h(n) is admissible, A* using TREE-SEARCH is optimal
for romania example, SLD is admissible
for 8-puzzle
- h1 = number of misplaced pieces
- h2 = manhattan distance
- both are admissible
  - manhattan is admissible bcz u cannot move diagonally in the grid