Search Algorithms and Problem-Solving Agents Chapter 3

A problem-solving agent looks ahead to find a sequence of actions that will achieve its goal even when the correct action is not immediately obvious.

Problem-solving agents use atomic representations, while planning agents use factored or structured representations of states.

The chapter discusses informed algorithms, which rely on estimates to goal states, and uninformed algorithms, which do not.

<p>The agent must decide which road to take from Arad, given that all three options lead away from the goal.</p> Signup and view all the answers

<p>If the environment is unknown, the agent must execute one of the actions at random.</p> Signup and view all the answers

<p>Chapter 4 relaxes the constraints on environments, expanding the discussion on search algorithms to more complex settings.</p> Signup and view all the answers

<p>The states are defined by the position of the agent and the presence or absence of dirt in each cell.</p> Signup and view all the answers

<p>Asymptotic complexity, indicated by O(n) notation, is important for understanding the efficiency of algorithms used by problem-solving agents.</p> Signup and view all the answers

<p>Factors include the desire to take in sights, improve language skills, enjoy nightlife, and avoid hangovers.</p> Signup and view all the answers

<p>The three actions are Suck, move Left (L), and move Right (R).</p> Signup and view all the answers

<p>The total number of states is $n \cdot 2^n$.</p> Signup and view all the answers

<p>A state space is a set of possible states that the environment can be in.</p> Signup and view all the answers

<p>The Suck action removes any dirt from the agent’s current cell.</p> Signup and view all the answers

<p>The initial state is the starting point for the agent, such as Arad in the given example.</p> Signup and view all the answers

<p>If the agent hits a wall while moving, the action has no effect.</p> Signup and view all the answers

<p>Goal states represent one or more desired outcomes that the agent aims to achieve.</p> Signup and view all the answers

<p>Additional movement actions like Upward and Downward could be introduced.</p> Signup and view all the answers

<p>Absolute movement actions are defined by fixed directions, while egocentric actions are defined relative to the agent's viewpoint.</p> Signup and view all the answers

<p>ACTIONS function returns a finite set of actions that can be executed in a given state.</p> Signup and view all the answers

<p>Any state can be designated as the initial state in a vacuum world.</p> Signup and view all the answers

<p>The transition model describes what each action does and the resulting state from executing an action.</p> Signup and view all the answers

<p>The action cost function gives the numeric cost of applying an action in a specific state to reach another state.</p> Signup and view all the answers

<p>The actions available are {ToSibiu, ToTimisoara, ToZerind}.</p> Signup and view all the answers

<p>RESULT(s, a) signifies the state that results from performing action a in state s.</p> Signup and view all the answers

<p>The agent and the box both move forward if there is an empty cell on the other side of the box.</p> Signup and view all the answers

<p>The primary actions are Backward, TurnRight, and TurnLeft.</p> Signup and view all the answers

<p>Goal states are the states in which every cell is clean.</p> Signup and view all the answers

<p>Each action costs 1.</p> Signup and view all the answers

<p>A state description specifies the location of each of the tiles.</p> Signup and view all the answers

<p>No, the agent cannot push a box into another box or a wall.</p> Signup and view all the answers

<p>The state space is given by the formula $\frac{n \times n!}{b! \times (n - b)!}$.</p> Signup and view all the answers

<p>The objective is to reach a specified goal state consisting of a 4 × 4 grid with one blank space.</p> Signup and view all the answers

<p>Breadth-first search is cost-optimal because it explores all nodes at depth d before finding solutions at that depth, ensuring that the first solution found is the one with the minimal number of actions.</p> Signup and view all the answers

<p>A FIFO queue is used to manage nodes in breadth-first search, allowing for the first-in-first-out processing of nodes.</p> Signup and view all the answers

<p>The 'reached' set keeps track of states that have already been explored to prevent processing the same state multiple times.</p> Signup and view all the answers

<p>Breadth-first search guarantees completeness as long as the search space is finite and it explores all potential nodes.</p> Signup and view all the answers

<p>The time complexity of breadth-first search is exponential in the depth of the solution, specifically $O(b^d)$, where d is the depth and b is the branching factor.</p> Signup and view all the answers

<p>If action costs vary, uniform-cost search may be necessary instead of breadth-first search to ensure the solution found is the least expensive.</p> Signup and view all the answers

<p>The 'expand' function generates all the child nodes of a given node, allowing the algorithm to explore all possible actions from that state.</p> Signup and view all the answers

<p>A higher branching factor increases the number of nodes generated and thus the time and space complexity of breadth-first search exponentially.</p> Signup and view all the answers

<p>Pitesti is added with a total cost of 177.</p> Signup and view all the answers

<p>Bucharest was not detected as a goal because the algorithm checks for goals only when expanding a node, not during node generation.</p> Signup and view all the answers

<p>The cost of the second path through Pitesti is 278.</p> Signup and view all the answers

<p>The complexity is O(b^{1+⌊C∗/ǫ⌋}).</p> Signup and view all the answers

<p>When all action costs are equal, uniform-cost search behaves like a breadth-first search.</p> Signup and view all the answers

<p>Uniform-cost search is complete and cost-optimal because it finds the first solution with the lowest cost.</p> Signup and view all the answers

<p>The parameter ǫ represents a lower bound on the cost of each action and must be greater than 0.</p> Signup and view all the answers

<p>Uniform-cost search systematically considers all paths in order of increasing cost.</p> Signup and view all the answers