Podcast
Questions and Answers
What is the time complexity of the depth-first search as mentioned in the content?
What is the time complexity of the depth-first search as mentioned in the content?
- O(b + l)
- O(b^l)
- O(l^b)
- O(bl) (correct)
In depth-limited search, how can a cutoff be indicated?
In depth-limited search, how can a cutoff be indicated?
- By returning a solution
- By returning the cutoff value (correct)
- By returning the maximum depth reached
- By returning the standard failure value
What does the diameter of the state space refer to in the context provided?
What does the diameter of the state space refer to in the context provided?
- The total number of possible sequences to investigate
- The maximum number of nodes in a search tree
- The maximum number of steps to reach any city from any other city (correct)
- The maximum depth of any goal node
Iterative deepening depth-first search gradually increases the limit starting from which number?
Iterative deepening depth-first search gradually increases the limit starting from which number?
What defines a problem formulation in a problem-solving approach?
What defines a problem formulation in a problem-solving approach?
In the context of recursive depth-limited search, what signifies that a solution has been found?
In the context of recursive depth-limited search, what signifies that a solution has been found?
Which of the following best describes a toy problem?
Which of the following best describes a toy problem?
What type of search algorithm is depth-limited search a special case of?
What type of search algorithm is depth-limited search a special case of?
In the context of the Vacuum World example, what is the goal test?
In the context of the Vacuum World example, what is the goal test?
What happens when the depth limit is reached in recursive depth-limited search?
What happens when the depth limit is reached in recursive depth-limited search?
What is the primary benefit of using iterative deepening depth-first search?
What is the primary benefit of using iterative deepening depth-first search?
What does the successor function represent in problem formulation?
What does the successor function represent in problem formulation?
Which statement about path cost is correct?
Which statement about path cost is correct?
What is a characteristic of a real-world problem?
What is a characteristic of a real-world problem?
In the 8-puzzle problem, what action can a tile perform?
In the 8-puzzle problem, what action can a tile perform?
For the initial state 'at Arad', what would be an example of a successor state?
For the initial state 'at Arad', what would be an example of a successor state?
What is a defining feature of the BS Algorithm?
What is a defining feature of the BS Algorithm?
What type of problem does not allow the agent to sense its environment?
What type of problem does not allow the agent to sense its environment?
In a contingency problem, what role do percepts play?
In a contingency problem, what role do percepts play?
What characterizes an exploration problem?
What characterizes an exploration problem?
In a sensorless problem, which of the following is true?
In a sensorless problem, which of the following is true?
Which term describes a state that an agent believes it to be in?
Which term describes a state that an agent believes it to be in?
What potential outcome can result from executing a 'Suck' action in a contingency problem?
What potential outcome can result from executing a 'Suck' action in a contingency problem?
Which search strategy is considered complete if the branching factor is finite?
Which search strategy is considered complete if the branching factor is finite?
What does the hill-climbing search algorithm primarily do?
What does the hill-climbing search algorithm primarily do?
What happens when a hill-climbing algorithm reaches a local maximum?
What happens when a hill-climbing algorithm reaches a local maximum?
What are ridges in the context of hill-climbing search?
What are ridges in the context of hill-climbing search?
How does a plateau affect the performance of the hill-climbing algorithm?
How does a plateau affect the performance of the hill-climbing algorithm?
Why is hill-climbing sometimes referred to as a greedy local search?
Why is hill-climbing sometimes referred to as a greedy local search?
What does the function HILL-CLIMBING return?
What does the function HILL-CLIMBING return?
Which of the following is a potential drawback of the hill-climbing algorithm?
Which of the following is a potential drawback of the hill-climbing algorithm?
What is typically replaced at each step in the hill-climbing algorithm?
What is typically replaced at each step in the hill-climbing algorithm?
What is the initial value of alpha during the start of the alpha-beta pruning algorithm?
What is the initial value of alpha during the start of the alpha-beta pruning algorithm?
When can the alpha value be updated in the pruning process?
When can the alpha value be updated in the pruning process?
At node B, what are the values of alpha and beta after evaluation?
At node B, what are the values of alpha and beta after evaluation?
What condition must be fulfilled for a node to be pruned?
What condition must be fulfilled for a node to be pruned?
What is the value of alpha at node E after its evaluation?
What is the value of alpha at node E after its evaluation?
What happens to the right successor of node E after pruning?
What happens to the right successor of node E after pruning?
How does the value of alpha at node A change after evaluating node B?
How does the value of alpha at node A change after evaluating node B?
What is the final alpha value at node F after evaluating its child nodes?
What is the final alpha value at node F after evaluating its child nodes?
What is the main characteristic of stochastic hill-climbing?
What is the main characteristic of stochastic hill-climbing?
How does simulated annealing differ from traditional hill-climbing methods?
How does simulated annealing differ from traditional hill-climbing methods?
What is a potential drawback of a purely random walk in search algorithms?
What is a potential drawback of a purely random walk in search algorithms?
In genetic algorithms, how are successor states generated?
In genetic algorithms, how are successor states generated?
What is the primary application of simulated annealing mentioned in the content?
What is the primary application of simulated annealing mentioned in the content?
Why might an algorithm using hill-climbing be considered incomplete?
Why might an algorithm using hill-climbing be considered incomplete?
What is the initial setup for a genetic algorithm?
What is the initial setup for a genetic algorithm?
What does the 'badness' of a move refer to in simulated annealing?
What does the 'badness' of a move refer to in simulated annealing?
Flashcards
Initial State
Initial State
Describes the starting point of a problem. It defines the initial conditions of the environment.
Successor Function
Successor Function
A function that maps a state to a set of possible actions and their resulting states. It represents the possible transitions from one state to another.
Goal Test
Goal Test
A criteria used to determine if a solution has been reached. This criteria can be explicit, like reaching a specific location, or implicit, like achieving a certain condition.
Path Cost
Path Cost
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Solution
Solution
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Toy Problem
Toy Problem
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Real-World Problem
Real-World Problem
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Vacuum World
Vacuum World
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Sensorless Problem
Sensorless Problem
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Contingency Problem
Contingency Problem
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Adversarial Problem
Adversarial Problem
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Exploration Problem
Exploration Problem
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Belief State
Belief State
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Solution (Sensorless)
Solution (Sensorless)
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Solution (Contingency)
Solution (Contingency)
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Contingency Planning
Contingency Planning
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Breadth-First Search
Breadth-First Search
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Greedy Best-First Search
Greedy Best-First Search
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A* Search
A* Search
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Depth-Limited Search
Depth-Limited Search
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Iterative Deepening Search
Iterative Deepening Search
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Backtracking Search
Backtracking Search
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Heuristic Search
Heuristic Search
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Graph Search
Graph Search
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Simulated Annealing
Simulated Annealing
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Hill Climbing
Hill Climbing
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Genetic Algorithm
Genetic Algorithm
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Stochastic Hill Climbing
Stochastic Hill Climbing
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First-Choice Hill Climbing
First-Choice Hill Climbing
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Random-Restart Hill Climbing
Random-Restart Hill Climbing
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Purely Random Walk
Purely Random Walk
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Beam Search
Beam Search
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Local maxima
Local maxima
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Ridges
Ridges
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Plateaux
Plateaux
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Hill-climbing search
Hill-climbing search
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Greedy local search
Greedy local search
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Current State
Current State
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Evaluation function
Evaluation function
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Highest valued successor
Highest valued successor
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Alpha-Beta Pruning
Alpha-Beta Pruning
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Alpha Value
Alpha Value
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Beta Value
Beta Value
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Pruning Condition
Pruning Condition
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Initial Alpha Value
Initial Alpha Value
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Initial Beta Value
Initial Beta Value
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Alpha-Beta Pruning Process
Alpha-Beta Pruning Process
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Alpha-Beta Pruning Termination
Alpha-Beta Pruning Termination
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Study Notes
Problem Solving by Search
- Problem solving involves finding a sequence of actions that lead to a desirable goal.
- A well-defined problem includes an initial state, an operator (successor) function to determine possible next states, a state space representing all reachable states, a path through the state space, a path cost function, and a goal test to check for a goal state.
- Search is a systematic method for examining states to find the path from the initial state to the goal state.
Search Space
- The search space consists of all possible states and the operators that define the connections between them.
- The output of a search algorithm is a solution, or a sequence of operations that leads from the initial state to a goal state.
Problem-Solving Agents
- A problem-solving agent is a goal-based agent designed for tasks by finding a sequence of actions that satisfy the goal.
Toy Problems
- Vacuum World Example: An agent is operating in a two-location world. The locations can contain or not contain dirt. Goal: All squares are clean.
- 8-Puzzle: A 3x3 board with tiles and a blank space. Goal is to reach a goal state.
- 8-Queens Problem: Eight Queens on a chessboard, no queen attacking another. Goal: Place all eight queens on the board.
Real-World Problems
- Route Finding: Finding the shortest path between locations. Example: Find the best route from Arad to Bucharest in Romania.
- Airline Travel: Finding the best route and time for travel.
- Touring Problems: Visiting each city at least once.
- VLSI Layout Problem: Arranging millions of components on a chip.
- Robot Navigation: Generalizing route-finding, a robot can move in a continuous space, with an infinite set of possible actions and states.
Uninformed Search Strategies
-
Breadth-First Search: Expands nodes in increasing depth.
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Uniform-Cost Search: Expands nodes with the lowest cost first. -Both strategies are complete but not always optimal.
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Depth-First Search: Explores as far as possible along each branch before backtracking.
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Depth-Limited Search: Depth-first search with a pre-defined depth limit.
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Iterative Deepening Search: Repeatedly applies depth-limited search with increasing depth limits.
Informed Search Strategies (Heuristic Search)
- Best-First Search: Expands nodes based on an evaluation function (f(n)).
- Greedy Best-First Search: Uses a heuristic function to estimate the distance to the goal (f(n) = h(n)).
- A* Search: Combines cost from start to current node (g(n)) and heuristic cost to goal node (h(n)),(f(n) =g(n) + h(n)). A* Search is optimal and if the heuristic is admissible (never overestimates the true cost) then A* is optimal.
- A* search is considered optimal among all algorithms because it never misses a better answer.
Local Search Algorithms
- Hill Climbing: A greedy algorithm that moves towards increasingly better solutions.
- Simulated Annealing: Stochastic algorithm combines greedy approach(hill-climbing) with random walk (expands any successor with probability, based on temperature).
- Genetic Algorithms: Searches by generating a population of possible solutions, then selecting those with the highest evaluation function, and combines parts of the best to create new solutions.
Constraint Satisfaction Problems (CSPs)
- A set of variables (X1, X2,…Xn) and a set of constraints (C1,C2,… Cm).
- Each variable has a domain (possible values).
- A constraint specifies allowed combinations of values for a subset of variables.
- Goal: Find a complete assignment of values to variables that satisfies all constraints.
- Example: Map Coloring, Cryptarithmetic, 8 Queens problem, etc
Adversarial Search
- Games are competitive environments. Players' goals are in direct conflict.
- Minimax Search: A game-playing algorithm.
- Alpha-Beta Pruning: An optimization technique for minimax search that reduces the number of nodes evaluated.
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