The document discusses informed search strategies that use problem-specific knowledge to improve problem-solving efficiency over uninformed search methods. Informed search methods, such as best-first search, use an evaluation function to prioritize expanding the most promising branches of the search space first. Heuristics provide estimates of the cost to reach the goal from each node to help identify the most informed search path. An ideal heuristic evaluation function guides the search to find solutions using the fewest nodes explored and calculates heuristic values quickly without much time overhead.

1. Informed Search Strategies
K. HariNath
Assistant Professor,
Department of IT,
MGIT
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2. INFORMED
SEARCH
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3. Informed search
■ We have seen that uninformed search methods that systematically
explore the state space and find the goals.
■ Inefficientin most cases.
■ Informed Search methods use problemspecific knowledge, are
more efficient.
■ Informed Search methodtriesto improveproblemsolving efficiencyby
using problemspecificknowledge.
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4. ■ A search strategy which searches the most promising branches of the
state-space first can:
– find a solution more quickly,
– find solutions even when there is limited time available,
– often find a better solution, since more profitable parts of the
state- space can be examined, while ignoring the unprofitable
parts.
■ A search strategy which is better than another at identifying the most
promising branches of a search-space is said to be more informed.
Continued
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5. ■ The general approach we consider is called best-first search. Best- first
search is an instance of the general TREE-SEARCH or GRAPH- SEARCH
algorithm in which a node is selected for expansion based on an
evaluation function, f(n).
■ The evaluation function is construed as a cost estimate, so the node
with the lowest evaluation is expanded first.
■ The implementation of best-first graph search is identical to that for
uniform-cost search (previous topic), except for the use of f instead of g
to order the priority queue.
Continued
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6. Heuristics
■ Heuristic is a rule of thumb.
■ “Heuristics are criteria, methods or
principles for deciding which
among several alternative courses of
action promises to be the most effective
in order to achieve some goals”,
Judea Pearl.
Can use heuristics to identify the most promising search path.
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7. ■ A heuristic function at a node n is an estimate of the optimum cost
from the current node to a goal. Denoted by h(n).
h(n)=estimated cost of the cheapest path from node n to a goal node.
■ Example
– Want to find the path from Vijayawada to Hyderabad
– Heuristic for Hyderabad may be straight line distance
between Vijayawada and Hyderabad.
– h(Vijayawada)=Euclidian distance(Vijayawada, Hyderabad)
Continued
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8. Heuristics
Example
■ 8-Puzzle: Number of tiles out of place
■ h(n)=5 (1,2,3,4,8 are not in correct location)
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9. Uninformed Search Vs. Informed Search
OR Heuristically Informed Search
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10. Uninformed Search Vs. Informed Search
OR Heuristically Informed Search
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11. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
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12. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
Heuristic
Evaluation
Function
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13. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
Heuristic
Evaluation
Function
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14. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
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15. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
Small Heuristic
Value
Better Path
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16. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
Small Heuristic
Value
Better Path
h(C)
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17. Uninformed Search Vs. Informed Search OR
Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
Small Heuristic
Value
Better Path
h(C) h(B)
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18. Uninformed Search Vs. Informed Search
OR Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
Small Heuristic
Value
Better Path
h(C) h(B)
<
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19. Uninformed Search Vs. Informed Search
OR Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
Small Heuristic
Value
Better Path
h(C) h(B)
C <
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20. Uninformed Search Vs. Informed Search
OR Heuristically Informed Search
Heuristic
Evaluation
Function
Heuristic Value
Small Heuristic
Value
Better Path
) h(B)
C <
Uninformed Search
NO INFORMATION
Direct Search BEST
PATH
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21. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
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22. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏 𝒉𝟐
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
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23. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏 𝒉𝟐
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
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24. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏 𝒉𝟐
𝟓
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
2/20/2021 24
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25. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏 𝒉𝟐
𝟓 𝟕
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
2/20/2021 25
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26. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
2/20/2021 26
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27. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
2/20/2021 27
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28. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝒉𝟏
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
2/20/2021 28
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29. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝒉𝟏 𝒉𝟐
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
𝑻𝒊𝒎𝒆
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30. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝒉𝟏 𝒉𝟐
𝟔𝟎𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
𝑻𝒊𝒎𝒆
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31. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝒉𝟏 𝒉𝟐
𝟔𝟎𝒔 𝟏𝟎𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
𝑻𝒊𝒎𝒆
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32. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝒉𝟐
𝟔𝟎𝒔 𝟏𝟎𝒔
𝒉𝟏 𝒉𝟐
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
𝑻𝒊𝒎𝒆
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33. Heuristic EvaluationFunction
• Good heuristic evaluationfunction is what directs searchto
reach goal with the smallest number of nodes.
• Good heuristic evaluation function is not time consuming in
the heuristic value calculation.
𝒉𝟏
𝟓 𝟕
𝒉𝟏 𝒉𝟐
𝟓
𝒉𝟐
𝟔𝟎𝒔 𝟏𝟎𝒔
𝒉𝟏 𝒉𝟐
𝟏𝟎𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
# 𝒐𝒇𝑵𝒐𝒅𝒆𝒔
𝑯
𝒆
𝒖
𝒓
𝒊
𝒔
𝒕
𝒊
𝒄𝑭𝒖𝒏𝒄𝒕𝒊𝒐𝒏
𝑻𝒊𝒎𝒆
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34. Best First Search
– The generic best-first search algorithm selects a
node for expansion according to an evaluation
function.
– It is a generalization of breadth first search.
– Priority queue of nodes to be explored.
– Cost function f(n) to applied to each node.
– Always choose the node from the frontier that
has lowest f(n) value.
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35. Greedy Search
■ Expand node with the smallest estimated cost to reach the goal.
■ Use heuristic function f(n)=h(n)
– This algorithm is not optimal
– Not complete
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36. Continued….
■ Greedy best-first search tries to expand the node that is closest to the
goal, on the grounds that this is likely to lead to a solution quickly
■ Thus, the evaluation function is f(n) = h(n)
■ E.g. in minimizing road distances a heuristic lower bound for distances
of cities is their straight-line distance
■ Greedy search ignores the cost of the path that has already been
traversed to reach n
■ Therefore, the solution given is not necessarily optimal
■ If repeating states are not detected, greedy best-first search may
oscillate forever between two promising states.
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37. Continued..
■ Because greedy best-first search can start down an infinite path
and never return to try other possibilities, it is incomplete
■ Because of its greediness the search makes choices that can lead to
a dead end; then one backs up in the search tree to the deepest
unexpanded node
■ Greedy best-first search resembles depth-first search in the way it
prefers to follow a single path all the way to the goal, but will back
up when it hits a dead end
■ The worst-case time and space complexity is O(bm)
■ The quality of the heuristic function determines the practical
usability of greedy search.
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38. Continue…
A
B
C
E
F
99
211
G
80
97
38
H
101
Start
75
118
111
D
I
Goal
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
2/20/2021 38
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39. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 39
MGIT-IT-HARINATH

40. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 40
MGIT-IT-HARINATH

41. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue..
2/20/2021 41
MGIT-IT-HARINATH

42. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue..
2/20/2021 42
MGIT-IT-HARINATH

43. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 43
MGIT-IT-HARINATH

44. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 44
MGIT-IT-HARINATH

45. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 45
MGIT-IT-HARINATH

46. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 46
MGIT-IT-HARINATH

47. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
2/20/2021 47
MGIT-IT-HARINATH

48. A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
140
Continue…
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MGIT-IT-HARINATH

49. Greedy Search: Tree
Search
Start
A
2/20/2021 49
MGIT-IT-HARINATH

50. Greedy Search: Tree Search
A
B
C
E
Start
75
118
140 [374]
[329]
[253]
2/20/2021 50
MGIT-IT-HARINATH

51. Greedy Search: Tree Search
A
B
C
E
F
99
G
A
80
Start
75
118
140 [374]
[329]
[253]
[193]
[366]
[178]
2/20/2021 51
MGIT-IT-HARINATH

52. Greedy Search: Tree Search
A
B
C
E
F
I
99
211
G
A
80
Goal
Start
75
118
140 [374]
[329]
[253]
[193]
[366]
[178]
E
[0]
[253]
2/20/2021 52
MGIT-IT-HARINATH

53. Greedy Search: Tree Search
A
B
C
E
F
I
99
211
G
A
80
Goal
Start
75
118
140 [374]
[329]
[253]
[193]
[366]
[178]
E
[0]
[253]
Path cost(A-E-F-I) = 253 + 178 + 0 = 431
dist(A-E-F-I)=140+99+211= 450
2/20/2021 53
MGIT-IT-HARINATH

54. Greedy Search: Complete ?
A
B
C
E
F
I
99
211
G
80
Goal
97
H
101
Start
75
118
111
D
f(n)= h(n) = straight-line distance heuristic
State Heuristic: h(n)
A 366
B 374
** C 250
D 244
E 253
F 178
G 193
H 98
I 0
140
2/20/2021 54
MGIT-IT-HARINATH

55. Greedy Search: Tree Search
Start
A
2/20/2021 55
MGIT-IT-HARINATH

56. Greedy Search: Tree Search
A
B
C
E
Start
75
MGIT-IT-HARINATH 56
118
140 [374]
[250]
[253]
2/20/2021

57. Greedy Search: Tree Search
A
B
C
E
D
Start
75
118
140 [374]
[250]
[253]
111
[244]
2/20/2021 57
MGIT-IT-HARINATH

58. Greedy Search: Tree Search
A
B
C
E
D
Start
75
118
140 [374]
[250]
[253]
111
[244]
C
[250]
Infinite Branch !
2/20/2021 58
MGIT-IT-HARINATH

59. Greedy Search: Tree Search
A
B
C
E
D
Start
75
118
140 [374]
[250]
[253]
111
[244]
C
D
[250]
[244]
Infinite Branch !
2/20/2021 59
MGIT-IT-HARINATH

60. Greedy Search: Tree Search
A
B
C
E
D
Start
75
118
140 [374]
[250]
[253]
111
[244]
C
D
[250]
[244]
Infinite Branch !
2/20/2021 60
MGIT-IT-HARINATH

61. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
2/20/2021 61
MGIT-IT-HARINATH

62. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎
2/20/2021 62
MGIT-IT-HARINATH

63. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎
𝒂𝟏𝟎
2/20/2021 63
MGIT-IT-HARINATH

64. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
2/20/2021 64
MGIT-IT-HARINATH

65. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕
𝒂𝟏𝟎
2/20/2021 65
MGIT-IT-HARINATH

66. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
2/20/2021 66
MGIT-IT-HARINATH

67. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
2/20/2021 67
MGIT-IT-HARINATH

68. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕
𝒂𝟏𝟎
𝒇𝟕
2/20/2021 68
MGIT-IT-HARINATH

69. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
2/20/2021 69
MGIT-IT-HARINATH

70. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑
2/20/2021 70
MGIT-IT-HARINATH

71. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
2/20/2021 71
MGIT-IT-HARINATH

72. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆𝟓
𝒈𝟑
2/20/2021 72
MGIT-IT-HARINATH

73. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
2/20/2021 73
MGIT-IT-HARINATH

74. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆𝟓
𝒈𝟑
2/20/2021 74
MGIT-IT-HARINATH

75. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
2/20/2021 75
MGIT-IT-HARINATH

76. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
2/20/2021 76
MGIT-IT-HARINATH

77. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓
2/20/2021 77
MGIT-IT-HARINATH

78. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
2/20/2021 78
MGIT-IT-HARINATH

79. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
2/20/2021 79
MGIT-IT-HARINATH

80. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
2/20/2021 80
MGIT-IT-HARINATH

81. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
2/20/2021 81
MGIT-IT-HARINATH

82. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔
2/20/2021 82
MGIT-IT-HARINATH

83. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
2/20/2021 83
MGIT-IT-HARINATH

84. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
2/20/2021 84
MGIT-IT-HARINATH

85. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
2/20/2021 85
MGIT-IT-HARINATH

86. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
2/20/2021 86
MGIT-IT-HARINATH

87. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒇
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝒇𝟕
𝒈𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝟓 𝒋𝟖,𝒃𝟏𝟎
𝒈𝟑
𝒆𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
2/20/2021 87
MGIT-IT-HARINATH

88. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Cost: Node to Node
Heuristic: Node to
Goal
2/20/2021 88
MGIT-IT-HARINATH

89. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristic
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 89
MGIT-IT-HARINATH

90. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristic 5
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 90
MGIT-IT-HARINATH

91. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 91
MGIT-IT-HARINATH

92. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 92
MGIT-IT-HARINATH

93. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost 3
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 93
MGIT-IT-HARINATH

94. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost 3 9
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 94
MGIT-IT-HARINATH

95. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost 3 9
Total
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 95
MGIT-IT-HARINATH

96. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost 3 9
Total 8
Cost: Node to
Node Heuristic:
Node to Goal
2/20/2021 96
MGIT-IT-HARINATH

97. Greedy Best-First
Search Goal – Node
K
𝒂𝟏𝟎 ---
Current Children
𝒂𝟏𝟎 𝒇𝟕, 𝒋𝟖,𝒃𝟏𝟎
𝒂𝟏𝟎
𝟓 𝟖 𝟏𝟎
𝒇
𝒇
𝟕
𝟕 𝒋𝟖,𝒃𝟏𝟎
𝒇𝟕 𝒈𝟑,𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒈
𝒈
𝟑
𝟑 𝒆𝟓, 𝒋𝟖,𝒃𝟏𝟎
𝒆
𝒆 𝒋 ,𝒃
𝟓
𝒆𝟓 𝒊𝟔,𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔 𝒋𝟖,𝒃𝟏𝟎
𝒊
𝟔
𝒊
𝟔 𝒌𝟎,𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎 𝒋𝟖,𝒃𝟏𝟎
𝒌𝟎
Similar to Uniform
Cost Just use
Heuristic
& Avoids Cost
Heuristi
c
5 2
Cost 3 9
Total 8 11
Cost: Node to Node
Heuristic: Node to
Goal
2/20/2021 97
MGIT-IT-HARINATH

98. Continue…
■ Greedy search is not optimal
■ Greedy search is incomplete without systematic
checking of repeated states.
■ In the worst case, the Time and Space
Complexity of Greedy Search are both O(bm ),
Where b is the branching factor and m the
maximum path length.
2/20/2021 98
MGIT-IT-HARINATH

99. A* Search
■ Greedy Search minimizes a heuristic h(n) which is an estimated cost
from a node n to the goal state. Greedy Search is efficient but it is not
optimal nor complete.
■ Uniform Cost Search minimizes the cost g(n) from the initial state to n.
UCS is optimal and complete but not efficient.
■ New Strategy: Combine Greedy Search and UCSto get an efficient
algorithm which is complete and optimal.
2/20/2021 99
MGIT-IT-HARINATH

100. Continue…
■ A* uses a heuristic function which f(n) = g(n) + h(n)
■ g(n) is the exact cost to reach node n from the initial state.
■ h(n) is an estimation of the remaining cost to reach the goal.
2/20/2021 100
MGIT-IT-HARINATH

101. n
g(n)
h(n)
f(n) = g(n)+h(n)
2/20/2021 101
MGIT-IT-HARINATH

102. A* Search
f(n)= g(n)+ h (n)
State Heuristic: h(n)
A 366
B 374
C 329
D 244
E 253
F 178
G 193
H 98
I 0
A
B
C
E
F
I
99
211
G
80
Start
Goal
97
H
101
75
118
111
D
140
g(n): is the exact cost to reach node n from the initial state.
2/20/2021 102
MGIT-IT-HARINATH

103. A* Search: Tree Search
A Start
2/20/2021 103
MGIT-IT-HARINATH

104. A* Search: Tree Search
A
B
E
Start
75
118
140
[393] [449]
[447] C
2/20/2021 104
MGIT-IT-HARINATH

105. A* Search: Tree Search
A
B
E
F
80
Start
75
118
140
[393]
99
[449]
[447] C
[417]
[413] G
2/20/2021 105
MGIT-IT-HARINATH

106. A* Search: Tree Search
A
B
E
F
80
Start
75
118
140
[393]
99
[449]
[447] C
[417]
H
[413] G
97
[415]
2/20/2021 106
MGIT-IT-HARINATH

107. A* Search: Tree Search
A
B
E
F
H
80
Start
97
75
118
140
[393]
99
[449]
[447] C
[417]
[413] G
[415]
Goal
101
I
[418]
2/20/2021 107
MGIT-IT-HARINATH

108. A* Search: Tree Search
A
B
E
F
H
80
Start
97
75
118
140
[393]
99
[449]
[447] C
[417]
[413] G
[415]
Goal
101
I
[418]
I [450]
2/20/2021 108
MGIT-IT-HARINATH

109. A* Search: Tree Search
A
B
E
F
H
80
Start
97
75
118
140
[393]
99
[449]
[447] C
[417]
[413] G
[415]
Goal
101
I [418]
I [450]
2/20/2021 109
MGIT-IT-HARINATH

110. A* Search: Tree Search
A
B
E
F
H
80
Start
97
75
118
140
[393]
99
[449]
[447] C
[417]
[413] G
[415]
Goal
101
I [418]
I [450]
2/20/2021 110
MGIT-IT-HARINATH

111. A* Search – Combines Heuristic &
Cost Goal - Bucharest
2/20/2021 111
MGIT-IT-HARINATH

112. A* Search –
Continue Goal -
Bucharest
2/20/2021 112
MGIT-IT-HARINATH

113. Arad
2/20/2021 113
MGIT-IT-HARINATH

114. Ara
d
Arad
2/20/2021 114
MGIT-IT-HARINATH

115. Ara
d
Arad
Arad
Children

116. Sibiu
Ara
d
Arad
Arad
Children
2/20/2021 116
MGIT-IT-HARINATH

117. Sibiu
Timisoara
Ara
d
Arad
Arad
Children
2/20/2021 117
MGIT-IT-HARINATH

118. Sibiu
Timisoara
Zerind
Ara
d
Arad
Arad
Children
2/20/2021 118
MGIT-IT-HARINATH

119. Sibiu
Timisoara
Zerind
Ara
d
Arad
Arad
Children
Calculate
Total Cost
2/20/2021 119
MGIT-IT-HARINATH

120. Sibiu
Timisoara
Zerind
Ara
d
Arad
Arad
Children
Calculate
Total Cost
Order
Asc.
2/20/2021 120
MGIT-IT-HARINATH

121. Sibiu
Timisoara
Zerind
Ara
d
Arad
Arad
Children
Calculate
Total Cost
Order
Asc.
Select
Min. Cost
2/20/2021 121
MGIT-IT-HARINATH

122. Sibiu
Timisoara
Zerind
Sibiu
Arad
Children
2/20/2021 122
MGIT-IT-HARINATH

123. Heuristic
Sibiu
Timisoara
Zerind
Sibiu
Arad
Children
2/20/2021 123
MGIT-IT-HARINATH

124. Heuristic Cost
Sibiu
Timisoara
Zerind
Sibiu
+
Arad
Children
2/20/2021 124
MGIT-IT-HARINATH

125. Heuristic Cost Total
Sibiu
Timisoara
Zerind
Sibiu
+
Arad
Children
=
2/20/2021 125
MGIT-IT-HARINATH

126. Heuristic Cost
253
Total
Sibiu
Timisoara
Zerind
Sibiu
+
Arad
Children
=
2/20/2021 126
MGIT-IT-HARINATH

127. Heuristic Cost
253 140
Total
Sibiu
Timisoara
Zerind
Sibiu
+ =
Arad
Children
+
2/20/2021 127
MGIT-IT-HARINATH

128. Heuristic Cost
253 140
Total
393
+
Sibiu
Timisoara
Zerind
Sibiu
+ =
Arad
Children
=
2/20/2021 128
MGIT-IT-HARINATH

129. Heuristic Cost
253 140
Total
393
+ =
Sibiu
Timisoara
Zerind
Sibiu
+ =
Arad
Children
2/20/2021 129
MGIT-IT-HARINATH

130. Heuristic Cost
253 140
Total
393
+ =
Sibiu
Timisoara
Zerind
Sibiu
+ =
Arad
Children
393
2/20/2021 130
MGIT-IT-HARINATH

131. Heuristic Cost Total
Sibiu
Timisoara
Zerind
Timisoara
+ =
Arad
Children
393
2/20/2021 131
MGIT-IT-HARINATH

132. Heuristic Cost
329
Total
Sibiu
Timisoara
Zerind
Timisoara
+ =
Arad
Children
393
2/20/2021 132
MGIT-IT-HARINATH

133. Heuristic Cost
329 118
Total
+
Sibiu
Timisoara
Zerind
Timisoara
+ =
Arad
Children
393
2/20/2021 133
MGIT-IT-HARINATH

134. Heuristic Cost
329 118
Total
447
+ =
Sibiu
Timisoara
Zerind
Timisoara
+ =
Arad
Children
393
2/20/2021 134
MGIT-IT-HARINATH

135. Heuristic Cost
329 118
Total
447
+ =
Sibiu
Timisoara
Zerind
Timisoara
+ =
Arad
Children
393
447
2/20/2021 135
MGIT-IT-HARINATH

136. Heuristic Cost Total
Sibiu
Timisoara
Zerind
Zerind
+ =
Arad
Children
393
447
2/20/2021 136
MGIT-IT-HARINATH

137. Heuristic Cost
374
Total
Sibiu
Timisoara
Zerind
Zerind
+ =
Arad
Children
393
447
2/20/2021 137
MGIT-IT-HARINATH

138. Heuristic Cost
374 75
Total
+
Sibiu
Timisoara
Zerind
Zerind
+ =
Arad
Children
393
447
2/20/2021 138
MGIT-IT-HARINATH

139. Heuristic Cost
374 75
Total
449
+ =
Sibiu
Timisoara
Zerind
Zerind
+ =
Arad
Children
393
447
2/20/2021 139
MGIT-IT-HARINATH

140. Heuristic Cost
374 75
Total
449
+ =
Sibiu
Timisoara
Zerind
Zerind
+ =
Arad
Children
393
447
449
2/20/2021 140
MGIT-IT-HARINATH

141. CurrentQueue
Sibiu
393
2/20/2021 141
MGIT-IT-HARINATH

142. CurrentQueue
Sibiu
393
Timisoar
a 447
2/20/2021 142
MGIT-IT-HARINATH

143. CurrentQueue
Sibiu
393
Timisoar
a 447
Zerin
d449
2/20/2021 143
MGIT-IT-HARINATH

144. CurrentQueue
Sibi
u
39
3
Timisoar
a 447
Zerin
d449
Sibiu
393
2/20/2021 144
MGIT-IT-HARINATH

145. Sibiu
2/20/2021 145
MGIT-IT-HARINATH

146. Sibi
u
Sibiu
2/20/2021 146
MGIT-IT-HARINATH

147. Arad
Sibi
u
Sibiu
Sibiu
Children
2/20/2021 147
MGIT-IT-HARINATH

148. Arad
Fagaras
Sibi
u
Sibiu
Sibiu
Children
2/20/2021 148
MGIT-IT-HARINATH

149. Arad
Fagaras
Orades
Sibi
u
Sibiu
Sibiu
Children
2/20/2021 149
MGIT-IT-HARINATH

150. Arad
Fagaras
Orades
Sibi
u
Sibiu
Sibiu
Children
Ramnicu
2/20/2021 150
MGIT-IT-HARINATH

151. Arad
Fagaras
Orades
Sibi
u
Sibiu
Sibiu
Children
Calculate
Total Cost
Ramnicu
2/20/2021 151
MGIT-IT-HARINATH

152. Arad
Fagaras
Orades
Sibi
u
Sibiu
Sibiu
Children
Calculate
Total Cost
Order
Asc.
Ramnicu
2/20/2021 152
MGIT-IT-HARINATH

153. Arad
Fagaras
Orades
Sibi
u
Sibiu
Sibiu
Children
Calculate
Total Cost
Order
Asc.
Select
Min. Cost
Ramnicu
2/20/2021 153
MGIT-IT-HARINATH

154. Arad
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
2/20/2021 154
MGIT-IT-HARINATH

155. Heuristic
Arad
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
2/20/2021 155
MGIT-IT-HARINATH

156. Heuristic Cost
Arad
+
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
2/20/2021 156
MGIT-IT-HARINATH

157. Heuristic Cost Total
Arad
+
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
=
2/20/2021 157
MGIT-IT-HARINATH

158. Heuristic Cost
366
Total
Arad
+
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
=
2/20/2021 158
MGIT-IT-HARINATH

159. Heuristic Cost
366 280
Total
+
Arad
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
2/20/2021 159
MGIT-IT-HARINATH

160. Heuristic Cost
366 280
Total
646
+ =
Arad
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
2/20/2021 160
MGIT-IT-HARINATH

161. Heuristic Cost
366 280
Total
646
+ =
Arad
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
2/20/2021 161
MGIT-IT-HARINATH

162. Heuristic Cost Total
Fagaras
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
2/20/2021 162
MGIT-IT-HARINATH

163. Heuristic Cost
176
Total
Fagaras
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
2/20/2021 163
MGIT-IT-HARINATH

164. Heuristic Cost
176 239
Total
+
Fagaras
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
2/20/2021 164
MGIT-IT-HARINATH

165. Heuristic Cost
176 239
Total
415
+ =
Fagaras
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
2/20/2021 165
MGIT-IT-HARINATH

166. Heuristic Cost
176 239
Total
415
+ =
Fagaras
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
2/20/2021 166
MGIT-IT-HARINATH

167. Heuristic Cost Total
Orades
+ =
Sibiu
Childre
n
Arad 646
Fagaras 415
Orades
Ramnicu
2/20/2021 167
MGIT-IT-HARINATH

168. Heuristic Cost
380
Total
Orades
+ =
Sibiu
Childre
n
Arad 646
Fagaras 415
Orades
Ramnicu
2/20/2021 168
MGIT-IT-HARINATH

169. Heuristic Cost
380 291
Total
+
Orades
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
2/20/2021 169
MGIT-IT-HARINATH

170. Heuristic Cost
380 291
Total
671
+ =
Orades
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
2/20/2021 170
MGIT-IT-HARINATH

171. Heuristic Cost
380 291
Total
671
+ =
Orades
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
671
2/20/2021 171
MGIT-IT-HARINATH

172. Heuristic Cost Total
Ramnicu
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
671
2/20/2021 172
MGIT-IT-HARINATH

173. Heuristic Cost
193
Total
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
671
Ramnicu
2/20/2021 173
MGIT-IT-HARINATH

174. Heuristic Cost
193 220
Total
+
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
671
Ramnicu
2/20/2021 174
MGIT-IT-HARINATH

175. Heuristic Cost
193 220
Total
413
+ =
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
671
Ramnicu
2/20/2021 175
MGIT-IT-HARINATH

176. Heuristic Cost
193 220
Total
413
+ =
+ =
Sibiu
Children
Arad
Fagaras
Orades
Ramnicu
646
415
671
413
Ramnicu
2/20/2021 176
MGIT-IT-HARINATH

177. CurrentQueue
Timisoar
a 447
Zerin
d449
2/20/2021 177
MGIT-IT-HARINATH

178. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Ramnic
u 413
Fagara
s 415
2/20/2021 178
MGIT-IT-HARINATH

179. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Ramnic
u 413
Fagara
s 415
2/20/2021 179
MGIT-IT-HARINATH

180. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Ramnic
u 41
3
Fagara
s 415
Ramnic
u 413
2/20/2021 180
MGIT-IT-HARINATH

181. Ramnicu
2/20/2021 181
MGIT-IT-HARINATH

182. Ramnic
u
Ramnicu
2/20/2021 182
MGIT-IT-HARINATH

183. Craiova
Ramnic
u
Ramnicu
Ramnicu
Children
2/20/2021 183
MGIT-IT-HARINATH

184. Craiova
Pitesti
Ramnic
u
Ramnicu
Ramnicu
Children
2/20/2021 184
MGIT-IT-HARINATH

185. Craiova
Pitesti
Sibiu
Ramnic
u
Ramnicu
Ramnicu
Children
2/20/2021 185
MGIT-IT-HARINATH

186. Craiova
Pitesti
Sibiu
Ramnic
u
Ramnicu
Ramnicu
Children
Calculate
Total Cost
2/20/2021 186
MGIT-IT-HARINATH

187. Craiova
Pitesti
Sibiu
Ramnic
u
Ramnicu
Ramnicu
Children
Calculate
Total Cost
Order
Asc.
2/20/2021 187
MGIT-IT-HARINATH

188. Craiova
Pitesti
Sibiu
Ramnic
u
Ramnicu
Ramnicu
Children
Calculate
Total Cost
Order
Asc.
Select
Min. Cost
2/20/2021 188
MGIT-IT-HARINATH

189. Craiova
Ramnicu
Children
Craiova
Pitesti
Sibiu
2/20/2021 189
MGIT-IT-HARINATH

190. Heuristic
Craiova
Ramnicu
Children
Craiova
Pitesti
Sibiu
2/20/2021 190
MGIT-IT-HARINATH

191. Heuristic Cost
Craiova
+
Ramnicu
Children
Craiova
Pitesti
Sibiu
2/20/2021 191
MGIT-IT-HARINATH

192. Heuristic Cost Total
Craiova
+
Ramnicu
Children
Craiova
Pitesti
Sibiu
=
2/20/2021 192
MGIT-IT-HARINATH

193. Heuristic Cost
160
Total
Craiova
+
Ramnicu
Children
Craiova
Pitesti
Sibiu
=
2/20/2021 193
MGIT-IT-HARINATH

194. Heuristic Cost
160 366
Total
+
Craiova
+ =
Ramnicu
Children
Craiova
Pitesti
Sibiu
2/20/2021 194
MGIT-IT-HARINATH

195. Heuristic Cost
160 366
Total
526
+ =
Craiova
+ =
Ramnicu
Children
Craiova
Pitesti
Sibiu
2/20/2021 195
MGIT-IT-HARINATH

196. Heuristic Cost
160 366
Total
526
+ =
Craiova
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
2/20/2021 196
MGIT-IT-HARINATH

197. Heuristic Cost Total
Pitesti
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
2/20/2021 197
MGIT-IT-HARINATH

198. Heuristic Cost
100
Total
Pitesti
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
2/20/2021 198
MGIT-IT-HARINATH

199. Heuristic Cost
100 317
Total
+
Pitesti
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
2/20/2021 199
MGIT-IT-HARINATH

200. Heuristic Cost
100 317
Total
417
+ =
Pitesti
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
2/20/2021 200
MGIT-IT-HARINATH

201. Heuristic Cost
100 317
Total
417
+ =
Pitesti
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
417
2/20/2021 201
MGIT-IT-HARINATH

202. Heuristic Cost Total
Sibiu
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
417
2/20/2021 202
MGIT-IT-HARINATH

203. Heuristic Cost
253
Total
Sibiu
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
417
2/20/2021 203
MGIT-IT-HARINATH

204. Heuristic Cost
253 300
Total
+
Sibiu
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
417
2/20/2021 204
MGIT-IT-HARINATH

205. Heuristic Cost
253 300
Total
553
+ =
Sibiu
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
417
2/20/2021 205
MGIT-IT-HARINATH

206. Heuristic Cost
253 300
Total
553
+ =
Sibiu
+ =
Ramnicu
Children
526
Craiova
Pitesti
Sibiu
417
553
2/20/2021 206
MGIT-IT-HARINATH

207. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Fagara
s 415
2/20/2021 207
MGIT-IT-HARINATH

208. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Fagara
s 415
Pitesti
417
Craiova
526
Sibiu
553
2/20/2021 208
MGIT-IT-HARINATH

209. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Fagara
s 415
Pitesti
417
Craiova
526
Sibiu
553
2/20/2021 209
MGIT-IT-HARINATH

210. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Fagar
as41
5
Pitesti
417
Craiova
526
Sibiu
553
Fagara
s 415
2/20/2021 210
MGIT-IT-HARINATH

211. Fagaras
2/20/2021 211
MGIT-IT-HARINATH

212. Fagar
as
Fagaras
2/20/2021 212
MGIT-IT-HARINATH

213. Sibiu
Fagar
as
Fagaras
Fagaras
Children
2/20/2021 213
MGIT-IT-HARINATH

214. Sibiu
Bucharest
Fagar
as
Fagaras
Fagaras
Children
2/20/2021 214
MGIT-IT-HARINATH

215. Sibiu
Bucharest
Fagar
as
Fagaras
Fagaras
Children
Calculate
Total Cost
2/20/2021 215
MGIT-IT-HARINATH

216. Sibiu
Bucharest
Fagar
as
Fagaras
Fagaras
Children
Calculate
Total Cost
Order
Asc.
2/20/2021 216
MGIT-IT-HARINATH

217. Sibiu
Bucharest
Fagar
as
Fagaras
Fagaras
Children
Calculate
Total Cost
Order
Asc.
Select
Min. Cost
2/20/2021 217
MGIT-IT-HARINATH

218. Heuristic Cost Total
Sibiu
+ =
Sibiu
Bucharest
Fagaras
Children
2/20/2021 218
MGIT-IT-HARINATH

219. Heuristic Cost
253
Total
Sibiu
+ =
Sibiu
Bucharest
Fagaras
Children
2/20/2021 219
MGIT-IT-HARINATH

220. Heuristic Cost
253 338
Total
+
Sibiu
+ =
Sibiu
Bucharest
Fagaras
Children
2/20/2021 220
MGIT-IT-HARINATH

221. Heuristic Cost
253 338
Total
591
+ =
Sibiu
+ =
Sibiu
Bucharest
Fagaras
Children
2/20/2021 221
MGIT-IT-HARINATH

222. Heuristic Cost
253 338
Total
591
+ =
Sibiu
+ =
591
Sibiu
Bucharest
Fagaras
Children
2/20/2021 222
MGIT-IT-HARINATH

223. Heuristic Cost Total
Bucharest
+ =
591
Sibiu
Bucharest
Fagaras
Children
2/20/2021 223
MGIT-IT-HARINATH

224. Heuristic Cost
0
Total
Bucharest
+ =
591
Sibiu
Bucharest
Fagaras
Children
2/20/2021 224
MGIT-IT-HARINATH

225. Heuristic Cost
0 450
Total
+
Bucharest
+ =
591
Sibiu
Bucharest
Fagaras
Children
2/20/2021 225
MGIT-IT-HARINATH

226. Heuristic Cost
0 450
Total
450
+ =
Bucharest
+ =
591
Sibiu
Bucharest
Fagaras
Children
2/20/2021 226
MGIT-IT-HARINATH

227. Heuristic Cost
0 450
Total
450
+ =
Bucharest
+ =
591
450
Sibiu
Bucharest
Fagaras
Children
2/20/2021 227
MGIT-IT-HARINATH

228. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Pitesti
417
Craiova
526
Sibiu
553
2/20/2021 228
MGIT-IT-HARINATH

229. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Pitesti
417
Craiova
526
Sibiu
591
Buchare
st 450
Sibiu
553
2/20/2021 229
MGIT-IT-HARINATH

230. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Pitesti
417
Craiova
526
Sibiu
591
Buchare
st 450
Sibiu
553
2/20/2021 230
MGIT-IT-HARINATH

231. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Pites
ti41
7
Craiova
526
Sibiu
591
Pitesti
417
Buchare
st 450
Sibiu
553
2/20/2021 231
MGIT-IT-HARINATH

232. Pitesti
2/20/2021 232
MGIT-IT-HARINATH

233. Pites
ti
Pitesti
2/20/2021 233
MGIT-IT-HARINATH

234. Bucharest
Pites
ti
Pitesti
Pitesti
Children
2/20/2021 234
MGIT-IT-HARINATH

235. Bucharest
Craiova
Pites
ti
Pitesti
Pitesti
Children
2/20/2021 235
MGIT-IT-HARINATH

236. Bucharest
Craiova
Ramnicu
Pites
ti
Pitesti
Pitesti
Children
2/20/2021 236
MGIT-IT-HARINATH

237. Bucharest
Craiova
Ramnicu
Pites
ti
Pitesti
Pitesti
Children
Calculate
Total Cost
2/20/2021 237
MGIT-IT-HARINATH

238. Bucharest
Craiova
Ramnicu
Pites
ti
Pitesti
Pitesti
Children
Calculate
Total Cost
Order
Asc.
2/20/2021 238
MGIT-IT-HARINATH

239. Bucharest
Craiova
Ramnicu
Pites
ti
Pitesti
Pitesti
Children
Calculate
Total Cost
Order
Asc.
Select
Min. Cost
2/20/2021 239
MGIT-IT-HARINATH

240. Heuristic Cost Total
Bucharest
+ =
Ramnicu
Children
Bucharest
Craiova
Ramnicu
2/20/2021 240
MGIT-IT-HARINATH

241. Heuristic Cost
0
Total
Bucharest
+ =
Ramnicu
Children
Bucharest
Craiova
Ramnicu
2/20/2021 241
MGIT-IT-HARINATH

242. Heuristic Cost
0 418
Total
+
Bucharest
+ =
Ramnicu
Children
Bucharest
Craiova
Ramnicu
2/20/2021 242
MGIT-IT-HARINATH

243. Heuristic Cost
0 418
Total
418
+ =
Bucharest
+ =
Ramnicu
Children
Bucharest
Craiova
Ramnicu
2/20/2021 243
MGIT-IT-HARINATH

244. Heuristic Cost
0 418
Total
418
+ =
Bucharest
+ =
Ramnicu
Children
418
Bucharest
Craiova
Ramnicu
2/20/2021 244
MGIT-IT-HARINATH

245. Heuristic Cost Total
Craiova
+ =
Ramnicu
Children
418
Bucharest
Craiova
Ramnicu
2/20/2021 245
MGIT-IT-HARINATH

246. Heuristic Cost
160
Total
Craiova
+ =
Ramnicu
Children
418
Bucharest
Craiova
Ramnicu
2/20/2021 246
MGIT-IT-HARINATH

247. Heuristic Cost
160 455
Total
+
Craiova
+ =
Ramnicu
Children
418
Bucharest
Craiova
Ramnicu
2/20/2021 247
MGIT-IT-HARINATH

248. Heuristic Cost
160 455
Total
615
+ =
Craiova
+ =
Ramnicu
Children
418
Bucharest
Craiova
Ramnicu
2/20/2021 248
MGIT-IT-HARINATH

249. Heuristic Cost
160 455
Total
615
+ =
Craiova
+ =
Ramnicu
Children
418
615
Bucharest
Craiova
Ramnicu
2/20/2021 249
MGIT-IT-HARINATH

250. Heuristic Cost Total
Ramnicu
+ =
Ramnicu
Children
418
615
Bucharest
Craiova
Ramnicu
2/20/2021 250
MGIT-IT-HARINATH

251. Heuristic Cost
193
Total
Ramnicu
+ =
Ramnicu
Children
418
615
Bucharest
Craiova
Ramnicu
2/20/2021 251
MGIT-IT-HARINATH

252. Heuristic Cost
193 414
Total
+
Ramnicu
+ =
Ramnicu
Children
418
615
Bucharest
Craiova
Ramnicu
2/20/2021 252
MGIT-IT-HARINATH

253. Heuristic Cost
193 414
Total
607
+ =
Ramnicu
+ =
Ramnicu
Children
418
615
Bucharest
Craiova
Ramnicu
2/20/2021 253
MGIT-IT-HARINATH

254. Heuristic Cost
193 414
Total
607
+ =
Ramnicu
+ =
Ramnicu
Children
418
615
607
Bucharest
Craiova
Ramnicu
2/20/2021 254
MGIT-IT-HARINATH

255. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Craiova
615
Sibiu
591
Buchare
st 450
Sibiu
553
Buchares
t 418
Craiova
526
Ramnic
u 607
2/20/2021 255
MGIT-IT-HARINATH

256. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Craiova
615
Sibiu
591
Buchare
st 450
Sibiu
553
Buchares
t 418
Craiova
526
Ramnic
u 607
2/20/2021 256
MGIT-IT-HARINATH

257. CurrentQueue
Arad
646
Timisoar
a 447
Zerin
d449
Orade
s 671
Craiova
615
Sibiu
591
Buchare
st 450
Sibiu
553
Buchare
st 41
8
Craiova
526
Ramnic
u 607
Buchare
st 418
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258. Bucharest
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259. Buchare
st
Bucharest
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260. Buchare
st
Bucharest
GOAL
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261. Path toGoal
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262. Analysis
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A* is optimally efficient for any given Consistent
heuristic.
A* Search is Complete, Optimal.
A* usually keeps all generated nodes in Memory.
A* runs out of space long before it runs out of time.
A* is not practical for many large-scale Problems.

263. A*(Admissible Heuristic)
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h(n) is Admissible Heuristic that never over estimates
the cost to reach the goal.

264. Memory Bounded Heuristic Search
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IDA*
Simplest way to reduce memory requirements is to adapt
idea of Iterative Deepening to Heuristic Search content.
Difference
-Use Cutoff f-cost(f+g) rather than depth.(IDA*)

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Memory Bounded Heuristic Search
Recursive BFS(Best First Search)
Simple recursive algorithm
Similar to Recursive Depth-First Search but uses f-limit
variable to keep track of f-value of best alternative path.
If Current Node exceeds the limit then back track choose
alternate path.
RBFS replaces f-value of each node along the path with
the backed up value(best f-value of its children)

266. Analysis
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IDA* and RBFS suffer from using too little memory.
IDA* retains only current f-cost limit
RBFS retains more information in Memory but it uses
Linear Space.

267. Using available Memory in A*
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MA*(Memory Bound A*)
SMA*(Simplified Memory Bound A*)
SMA* is simple, similar to A*(expands best leaf node until
Memory is full)
SMA* always drops the worst leaf node(one with highest
f-value).
SMA* backs up value of the forgotten node to its
parent(like RBFS)

268. Heuristic Functions
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Technique to solve problems quickly
Eg: 8 Puzzle Problem(320-Search Space possible)
h1- No of misplaced tiles
h2-Mahanhatten Distance
h2- admissible

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Generating Admissible Heuristic from
Relaxed Problems
Problem with fewer restrictions(Relaxed Problem)
Super Graph(State Space Graph of Relaxed Problem)
Creates additional edges(Removal of restrictions)
Relaxed Problems better solution if added edges provide
shortcuts.

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Generating Admissible Heuristic from
Sub Problems
Pattern Databases.
Store exact solution costs for every possible subproblem
instance.
Compute Admissible Heuristic for Complete State by
observing corresponding sub problem configuration in
Database.

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Learning Heuristic from Experience
Experience (Solving lot of Problems).
Construct function h(n)-(from example problems)
Inductive Learning(Works Best when supplied with
features of the State that are relevant to predicting states
value)

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Thank you