Questions tagged [search]

For questions involving search algorithms and their use in artificial intelligence

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18 views

What is a example showing that the tree-based variant for the greedy best-first search is incomplete?

I understand that a tree-based variant will have nodes repeatedly added to the frontier. How do I craft an example where a particular goal node is never found. Is this example valid. On the other ...
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0answers
48 views

Wooden railway search problem AI

I have this problem. A basic wooden railway set contains the pieces shown in Figure 3.32. The task is to connect these pieces into a railway that has no overlapping tracks and no loose ...
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0answers
30 views

Constraint Satisfaction for light switches problem

While revising on the topic of constraint satisfaction, I came across a question on light switches which asks us to formulate the problem as a CSP. This problem was taken from stanford's cs221 ...
2
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1answer
63 views

What is the difference between hill-climbing and greedy best-first search algorithms?

While watching MIT's lectures about search, 4. Search: Depth-First, Hill Climbing, Beam, the professor explains the hill-climbing search in a way that is similar to the best-first search. At around ...
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0answers
32 views

2 Partition Problem

I want to solve the two partition problem (https://en.wikipedia.org/wiki/Partition_problem) using an uninformed search algorithm (BFS or uniform cost). The states can be represented by three sets S1,...
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0answers
59 views

How can I apply the alpha-beta pruning algorithm to the “1-2 steal marbles” problem?

I have the following problem called "1-2 steal marbles". Initially, there are 6 marbles on the board. One of the players can choose to remove 1 or 2 marbles leaving 5 or 4. After that, the other ...
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0answers
27 views

How can I formulate a nonogram problem as a constraint satisfaction problem?

I've just started learning CSP and I find it quite exciting. Now I'm facing nonogram solving problem and I want to solve it using backtracking with CSP. The first problem that I face is that I cannot ...
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1answer
62 views

What does a consistent heuristic become if an edge is removed in A*?

For the A* algorithm, a consistent heuristic is defined as follows: if, for every node $n$ and every successor $m$ of $n$ generated by any action $a$, $h(n) \leq c(n,m) + h(m)$. Suppose the edge $c(...
2
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1answer
22 views

Agents meeting in a directed connected graph

I've just started learning AI and I have a certain problem: We have directed connected graph, where nodes are places one can go to and edges are the "roads" between places. We have K agents whose ...
3
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1answer
52 views

What does the statement with the max do in the recursive best-first search algorithm?

I am reading the book "Artificial Intelligence: A Modern Approach" by Stuart and Norvig. I'm having trouble understanding a step of the recursive best-first search (RBFS) algorithm. Here's the ...
3
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1answer
78 views

Is the summation of consistent heuristic functions also consistent?

Imagine that we have a set of heuristic functions $\{h_i\}_{i=1}^N$, where each $h_i$ is both admissible and consistent (monotonic). Is $\sum_{i=1}^N h_i$ still consistent or not? Is there any proof ...
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2answers
682 views

What are the properties of hill climbing?

What are the properties of hill climbing? More precisely, does it encounter any of the following phenomena? Local maxima Inadmissible heuristic Ridges Plateau
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1answer
106 views

Why is the space-complexity of greedy best-first search is $\mathcal{O}(b^m)$?

I am reading through Artificial Intelligence: Modern Approach and it states that the space complexity of the GBFS (tree version) is $\mathcal{O}(b^m)$. While I am reading, at some points, I found ...
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1answer
43 views

How to report the solution path of a search algorithm on a graph?

I'm working on a problem where we are given a graph and asked to perform various search algorithms (BFS, DFS, UCS, A*, etc.) and the goal state is to visit all nodes in the graph. After all nodes are ...
2
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1answer
61 views

Understanding the pseudocode of uniform-cost search from the book “Artificial Intelligence: A Modern Approach”

On page 84 of Russell & Norvig's book "Artificial Intelligence: A Modern Approach Book" (3rd edition), the pseudocode for uniform cost search is given. I provided a screenshot of it here for your ...
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1answer
31 views

FastDownward PDDL Planner Limitations

I recently had a look at automated planners and experimented a little bit with FastDownward. As I wanted to start a toy project, I created a PDDL model for the ordinary 3D Rubik's Cube (of course ...
4
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1answer
54 views

Why is it possible to eliminate this branch with alpha-beta pruning?

Can someone explain to me why it is possible to eliminate the rest of the middle branch in this image for alpha-beta pruning? I am confused because it seems the only information you know is that Helen ...
1
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1answer
118 views

Why is the effective branching factor used for measuring performance of a heuristic function?

For search algorithms with heuristic functions, performance of heuristic functions are measured by effective branching factor ${b^*}$ which involves total nodes expanded ${N}$ and depth of the ...
3
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1answer
108 views

A* and uniform-cost search are apparently incomplete

Consider the following diagram of a graph representing a search space. If we start at $B$ and try to reach goal state $E$, the lowest-cost first search (LCFS) (aka uniform-cost search) algorithm ...
5
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1answer
356 views

How to create an AI to solve a word search?

This at first sounds ridiculous. Of course there is an easy way to write a program to solve a wordsearch. But what I would like to do is write a program that solves a word-search like a human. That ...
4
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2answers
724 views

If an heuristic is not admissible, can it be consistent?

I am solving a problem in which, according to the given values, the heuristic is not admissible. According to my calculation from other similar problems, it should be consistent, as well as keeping in ...
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0answers
57 views

How to choose the weights for a linear combination of heuristic functions?

I need to write a minimax algorithm with alpha-beta pruning in limited time for the 2048 game. I know expectimax is better for this work. Assume I wrote different heuristic functions. If I want to ...
6
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1answer
68 views

Can two admissable heuristics not dominate each other?

I am working on a project for my artificial intelligence class. I was wondering if I have 2 admissible heuristics, A and B, is it possible that A does not dominate B and B does not dominate A? I am ...
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1answer
64 views

In the graph search version of A*, can I stop the search the first time I encounter the goal node?

I am going through Russel and Norvig's Artificial Intelligence: A Modern Approach (3rd edition). I was reading the part regarding the A* algorithm A* graph search version is optimal when heuristic ...
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1answer
127 views

How do we determine whether a heuristic is better than another?

I am trying to solve a Maze puzzle using the A* algorithm. I am trying to analyze the algorithm based on different applicable heuristics. Currently, I explored the Manhattan and Euclidean distances. ...
2
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1answer
99 views

Understanding the proof that A* search is optimal

I don't understand the proof that $A^*$ is optimal. The proof is by contradiction: Assume $A^*$ returns $p$ but there exists a $p'$ that is cheaper. When $p$ is chosen from the frontier, assume $...
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1answer
78 views

How to transform a PDDL to search?

I have a question about search and planning: I still haven't understood the difference from the two, but they seem very similar to me; here is a question I am struggling with: "Having formulated a ...
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2answers
84 views

Why is a mix of greedy and random usually “best” for stochastic local search?

I read that a mix of "greedy" and "random" are ideal for stochastic local search (SLS), but I'm not sure why. It mentioned that the greedy finds the local minima and the randomness avoids getting ...
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0answers
77 views

Can AC-3 algorithm solve N-Queens problem?

I am building CSP NQueens solver and apply the AC-3 algorithm.But,the domain reduction doesn't occur and gets more search time.How does it happen?Is it a nature of AC-3 algorithm?
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1answer
96 views

A* is similar to Dijkstra with reduced cost

According to this Wikipedia article If the heuristic $h$ satisfies the additional condition $h(x) ≤ d(x, y) + h(y)$ for every edge $(x, y)$ of the graph (where $d$ denotes the length of that edge), ...
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2answers
40 views

What is the proof that the branch and bound algorithm always finds optimal path in a graph?

I've been studying Branch and Bound's graph algorithm and I hear it always finds the optimal path because it uses previously found solutions to find others However, I haven't been able to find a ...
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1answer
234 views

Using graph searching to solve peg solitaire?

Problem: I've been reading research papers on how to solve a peg solitaire using graph searching, but all the papers kind of assume you know how to do the reduction(polynomial time conversion) from ...
2
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1answer
28 views

what are the similarity measure use for both continuous and categorical data?

I have searched but found that some similarity measures are for continuous data and some are for categorical data. But i want to know the similarity measures which are use for both data, continuous ...
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1answer
149 views

Is this ExpectiMinimax Tree correctly drawn?

I need help with ExpectiMinimax problem: Start a game. The first player flips a coin. The second player flips a coin. The first player decides if he wants to flip another coin. The second player ...
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1answer
88 views

How do I choose the search algorithm for a particular task?

How do I choose the search algorithm for a particular task? Which criteria should I take into account?
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2answers
66 views

How can the A* algorithm be optimized?

How can the A* algorithm be optimized? Any references that shows the optimization of A* algorithm are also appreciated.
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1answer
211 views

Why is informed search more efficient than uninformed search?

Why does informed search more efficiently finds a solution than an uninformed search?
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2answers
154 views

What is the difference between search and learning?

I came across an article, The Bitter Truth, via the Two Minute Papers YouTube Channel. Rich Sutton says... One thing that should be learned from the bitter lesson is the great power of general ...
2
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1answer
304 views

Is the minimum and maximum of a set of admissible and consistent heuristics also consistent and admissible?

Let's suppose I have a set of heuristics $H$ = {$h_1, h_2, ..., h_N$}. If all heuristics in $H$ are admissible, does that mean that a heuristic that takes the $\min(H)$ (or $\max(H)$ for that matter) ...
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1answer
276 views

How could we solve the TSP using an hill-climbing approach?

How could we solve the TSP using an hill-climbing approach?
3
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1answer
195 views

How do I find whether this heuristic is or not admissible and consistent?

I was given the following problem to solve. Given a circular trail divided by $n> 2$ segments labeled $0 \dots n-1$. In the beginning, an agent is at the start of segment number $0$ (the edge ...
3
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1answer
38 views

What are the common techniques one could use to deal with collisions in a Transposition Table?

Consider an iterative deepening search using a transposition table. Whenever the transposition table is full, what are common strategies applied to replace entries in the table? I'm aware of two ...
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2answers
386 views

How can I solve part b of exercise 3.6 from the book “Artificial Intelligence: A Modern Approach”?

I am trying to solve part b of the exercise 3.6 (page 113) from the book Artificial Intelligence: A Modern Approach. More specifically, I need to give a complete problem formulation (that is precise ...
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1answer
84 views

How do I model the blocked N queens problem as a search problem?

The blocked N-queens is a variant of the N-queens problem. In the blocked N-queens problem, we also have a NxN chess board and N queens. Each square can hold at most one queen. Some squares on the ...
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1answer
1k views

What is the difference between search and planning?

I'm studying Artificial Intelligence. A Modern Approach, Stuart Russell, Peter Norvig, specifically about search and planning arguments. I don't understand the difference between the two terms. I was ...
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0answers
196 views

How does DARTS compare to ENAS?

How does DARTS compare to ENAS? Which one is better or what advantages does they each have? Links: DARTS: Differentiable Architecture Search Efficient Neural Architecture Search via Parameter ...
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1answer
353 views

Does quiescence search even improve the minimax algorithm?

Consider this game state: d5 captures c6 Quiescence search returns about 8.0 as evaluation because after dxc6 and bxc6 Qxd6 would be played (then Qxd6 by black). A normal player would not play this ...
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2answers
1k views

Can someone help me to understand the alpha-beta pruning algorithm?

I understand the minimax algorithm, but I am unable to understand deeply the minimax algorithm with alpha-beta pruning, even after having looked up several sources (on the web) and having tried to ...
3
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2answers
488 views

When should I use simulated annealing as opposed to a genetic algorithm?

What kind of problems is simulated annealing better suited for compared to genetic algorithms? From my experience, genetic algorithms seem to perform better than simulated annealing for most problems....
2
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1answer
59 views

What kind of search method is A*?

What kind of search method is A*? Explain to me with an example.