Questions tagged [search]

For questions involving search algorithms and their use in artificial intelligence

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20 views

How does the second phase of the evaluation function described in this article work?

I am trying to create an evaluation function for a general game player based on the research from this article An Automatically-Generated Evaluation Function in General Game Playing. I can't ...
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17 views

Which method of tree searching should be used for this board game?

Suppose the following properties of a board game: High branching factor in the beginning of the game (~500) which slowly tends towards 0 at the end of the game Evaluation of the any given board ...
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2answers
1k views

Why is depth-first search an artificial intelligence algorithm?

I'm new to the artificial intelligence field. In our first chapters, there is one topic called "problem-solving by searching". After searching for it on the internet, I found the depth-first ...
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14 views

Does the selective search algorithm in object detection learn?

I am trying to get a better grasp of how object detection works. I (almost) completely understand the concept behind RPNs. However I am little bit confused with the selective search algorithm part. ...
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33 views

Suggestion for an Enterprise search engine: What are all the way I can use machine learning/dnn/nlp to enhance elasticsearch results?

We are building an enterprise search engine for about 130,000 documents. It includes FAQs, Small articles to 3-4 page documents, all of them are stored in structured JSON. We were originally planning ...
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1answer
69 views

Is A* with an admissible but inconsistent heuristic optimal?

I understand that, in tree search, an admissible heuristic implies that $A*$ is optimal. The intuitive way I think about this is as follows: Let $P$ and $Q$ be two costs from any respective nodes $p$ ...
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1answer
79 views

How does best-first search differ from hill-climbing?

How does best-first search differ from hill-climbing?
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1answer
61 views

Which heuristics guarantee the optimality of A*?

The following is a statement and I am trying to figure out if it's True or False and why. Given a non-admissible heuristic function, A* will always give a solution if one exists, but there is no ...
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1answer
34 views

Doesn't the number of explored nodes with IDA* increase linearly?

I think I'm misunderstanding the description of IDA* and want to clarify. IDA* works as follows (quoting from Wiki): At each iteration, perform a depth-first search, cutting off a branch when its ...
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26 views

How to implement NLP for ecommerce product search

I'm implementing an ecommerce search using nlp. there is a lack of clear documentation anywhere online about implementation and flow. this is what i'm doing. Search query comes in Do spellcheck Do ...
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0answers
56 views

Can we solve an $8 \times 8$ sliding puzzle using hill climbing?

Can we solve an $8 \times 8$ sliding puzzle using a random-restart hill climbing technique (steepest-ascent)? If yes, how much computing power will this need? And what is the maximum $n \times n$ that ...
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29 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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102 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 ends where a ...
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41 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 ...
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1answer
622 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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39 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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70 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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36 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
76 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(...
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1answer
32 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 ...
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1answer
66 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 ...
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1answer
131 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
758 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
244 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
67 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 ...
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1answer
91 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
51 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 ...
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1answer
78 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 ...
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1answer
213 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 ...
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1answer
145 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 ...
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1answer
468 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 ...
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2answers
1k 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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67 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 ...
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1answer
83 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
70 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
172 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. ...
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1answer
134 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
88 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
93 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
80 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
111 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
46 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
255 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 ...
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1answer
31 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
168 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
93 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
78 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
284 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
170 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 ...
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1answer
473 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) ...