Questions tagged [a-star-search]
The a-star-search tag has no usage guidance.
23
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Simplified Memory Bounded A*
I have been studying the SMA* algorithm and I am having trouble understanding the backup operation. Specifically, I don't understand why the f value of a child node should be the maximum of its own f ...
- 11
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94
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How to avoid costly square root operations in A* algorithm?
As a reminder, in an A* algorithm, vertices in the priority queue are sorted according to their priority $f = g + h$, where $g$ is the cost of getting to this vertex from the start vertex, and $h$ is ...
- 685
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80
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Optimality of A* algorithm
In the book Artificial Intelligence a Modern Approach 4th edition, the author claims that the A* algorithm is cost-optimal if the heuristic function is ...
- 111
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How is this "pathmax modification," $f(n^\prime) = \max(g(n^\prime) + h(n^\prime), f(n))$, useful?
I am studying the concept of heuristics in search algorithms, and the $A^*$ search algorithm in particular. I am told the following:
Greedy search minimises estimated path-cost to goal.
But it's ...
- 203
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93
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A* pseudocode problem
What is the difference between this two pseudocode and which one should i implement?
...
- 11
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192
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Any-goal bidirectional A* pathfinding reference
I want to solve the problem of finding a shortest path on a directed weighted graph from a certain node to any of a specified set of destination nodes (preferably the closest one, but that's not that ...
- 121
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452
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Difference between cost and the heuristic function in A* search
Looking at the image above, thinking in terms of A* search. I don't fully understand the heuristic function. The cost makes sense, so thinking in terms of a traditional map or navigation scenario. I'd ...
- 123
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91
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A* (A-star) path finding in continuous environments with "sticky slower" areas
I have a search problem, finding the shortest path for 3 vehicles to their parking spots, in a continuous environment (inputs are continuous for velocity, turn speed) and the location is continuous, ...
- 207
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111
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D* Lite - can edge costs be asymmetric?
I'm trying to modify the original D* Lite algorithm adding a margin constraint wrt to any nearby obstacle to be satisfied for each selected cell in the path. This causes the edge cost function between ...
- 145
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261
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Should your heuristic for an A* search algorithm be the same scale as your actual weights?
I'm a bit confused about the scale of heuristics for implementing A* search. $f(n)$ is the total cost of travelling to a node $n$. It is calculated by $f(n) = g(n) + h(n)$. $g(n)$ is the cost of the ...
- 13
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264
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Using A* path finding is giving me inaccurate results
So I am using A* pathfinding to find a path from a person, to a node on a graph. This person has a few 'must pass' nodes that they must go through. So my solution was to run the algorithm for each of ...
- 21
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Are there graphs for which A* cannot be admissible?
Wikipedia states that "On infinite graphs with a finite branching factor and edge costs that are bounded away from zero $ (d(x,y)>\varepsilon >0$ for some fixed $\varepsilon$), A* is guaranteed ...
- 143
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45
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Finding multiple paths through a grid such that every grid square is equally used
Setup
Here’s the setup: I have an $N$ x $N$ grid of tiles, and a list of $M$ agents that need to move across the grid. Each agent has its own start tile $S(a)$, end tile $E(a)$, and an exact number ...
- 151
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92
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Why doesn't A* give the optimal path for navigating from A to R in this state space?
Well, I have heard that the A* algorithm is optimal and complete. However, when trying to navigate from A to R using A*, it outputs the path, A --> E --> R, although there is a shorter path, A --> M --...
- 131
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Comparing classical tree-search algorithms (BFS,DFS,A*,IDS) - when to use one or the other?
I have a question about classical tree-search algorithms as I will have an exam soon and this is the type of questions they might be asking. Although I know how to compare the complexities, optimality,...
- 401
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887
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Coefficients in cost function in A-star
I'd like to expand on this question :
https://stackoverflow.com/questions/52420788/why-does-the-a-star-algorithm-need-gn
Dijkstra's algorithm uses cost function $f(n) = g(n)$
whereas A* uses cost ...
- 685
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330
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Can Dijkstra's algorithm outperform A star, in terms of vertices checked?
I know Dijkstra's algorithm can be seen as a specific case of A star, when the estimation heuristic used simply returns 0, so I know that A star with this specific heuristic can not check more ...
- 685
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2k
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A* without heuristic more efficient than Dijkstra
I am using the module networkx to operate on graphs made from OpenStreetMap.
I wanted to compare the shortest path algorithm to ...
- 21
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82
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cheap multi agent path planning algorithms
I am trying to make a tower defence game where some critters are trying to make their ways through a 2D grid-like obstacle course. The idea is these critters cannot walk into the obstacles or into ...
- 123
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75
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Heuristic for searching for solutions on an 8-puzzle variant with non-unique tiles
I'm trying to perform an A* search on a particular N-puzzle variant in which some tiles are identical. More specifically, assuming an $m \times m$ grid, there are m colors with m tiles of each. The ...
- 151
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702
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How can an A* algorithm visit all nodes?
Is it possible to find the shortest path and visit all the nodes in a graph by A* algorithm? If yes, how?
- 101
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56
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Term for an A*-like pathfinding strategy where only the heuristic goal distance matters
I am trying to find a proper term for the A*-like best-first pathfinding strategy where the node to expand next is the one with the least estimated distance from the goal, regardless of its distance ...
- 251
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660
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Does an optimal path imply the heuristic is admissible?
If we are given an A$^*$ path search with some heuristic $h$ that yields an optimal path, without knowing that the heuristic is admissible beforehand, would this imply that $h$ is admissible?
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