Questions tagged [heuristics]

Questions about algorithmic strategies that quickly solve a problem well most of the time, but give no guarantees.

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Greedy Heuristics with an Altered Subset Sum/Partition Problem

Say we have a constant-time function that accepts some integer set. The function outputs True if we can split the integers into two subsets of an equal sum. If we can't partition the integers given, ...
51 views

How do evaluation functions influence the optimal sequence of moves?

Assume you have a game tree and the features $(f_1, f_2, f_3,\ldots,f_n )$ that describe the state of the game at any node. Also assume that you are using depth-limited minimax and always expand up to ...
16 views

What is the difference between nearest and cheapest insertion algorithms for a Traveling salesman problem?

I know that in the cheapest insertion algorithm we include the node which is not in the "base group" that has smaller cost given all possible combinations, and for the nearest we include the node with ...
33 views

What is meant by a preemptive algorithm?

The definition on Google says 'serving or intended to pre-empt or forestall something, especially to prevent attack by disabling the enemy.' So, how does this relate to an algorithm, especially the ...
17 views

Comparison of constructive and local-search heuristics for TSP

In my high school class, we are currently looking at evaluating heuristic methods for intractable problems - especially TSP. My question is what is the advantages or disadvantages of using a ...
53 views

Matching of two weighted graphs allowing one-to-many mapping

I am looking for a heuristic for a graph matching problem as follows. Given two graphs: $A$ (consisting of nodes $a_i$) and $B$ (consisting of nodes $b_i$). Typically the size of $B$ is larger than ...
75 views

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 ...
48 views

Can data be compressed through this hash function technique?

I'd like to know if this data compression scheme would work or not, and why: Suppose we have a file. If we treat the bits that make up the file as the binary representation of a number n, we have n (...
95 views

Heuristics vs meta-heuristics vs hyper-heuristics?

The wikipedia page on meta-heuristics states that they are "heuristics designed to find, generate, or select a heuristic". The wikipedia page on hyper-heuristics states that they are "heuristic ...
91 views

How do you prove a heuristic is admissible?

How does one prove that a suggested heuristic is admissible? Is this even possible? For Example: Let's say I have the game Free Cell. Rules: https://en.wikipedia.org/wiki/FreeCell How can I ...
46 views

Why is the usual simulated annealing algorithm using a Boltzmann probability?

I've coded a personal version for the simulated annealing problem, and I was wondering why, (other than by analogy to the physics), the probability is $$p = e^{-\dfrac{\Delta \text{length}}{T}}$$ (...
625 views

Measuring the difficulty of SAT instances

Given an instance of SAT, I would like to be able to estimate how difficult it will be to solve the instance. One way is to run existing solvers, but that kind of defeats the purpose of estimating ...
2k views

How does the nearest insertion heuristic for TSP work?

In my theoretical computer science class and we were covering "Heuristics". In it we covered "Greedy Heuristics" for the "Vertex Cover Problem", "Interval Scheduling" and the "Traveling Salesperson ...
39 views

What kind of standard deviation must be used in optimization algorithms?

I would like to ask about the standard deviation of objective function value. There are two types of standard deviations: Population standard deviation Sample standard deviation In metaheuristic ...
168 views

Morphing Hypercubes, Token Sliding and Odd Permutations

A month ago, I asked the following question math.exchange (https://math.stackexchange.com/questions/3127874/morphing-hypercubes-and-odd-permutations), but for completeness, I will include the details ...
182 views

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?
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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 ...
52 views

Ant Colony optimisation for finding subsets with ~0 sum

I have a set A = [x1, x2...xn] where xi in R (real). I need to find all non intersecting subsets with subset sum ~0 (approximately equal to zero). Since the set can have non zero real numbers, I have ...
71 views

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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Overall time complexity of Heuristical Algorithm for travelling salesman problem [TSP]

I am trying to figure out the time complexity of a heuristical algorithm used to solve the Travelling Salesman Problem in a more efficient way than by brute force, ($\theta(n!)$ or similar) The ...
27k views

How does an admissible heuristic ensure an optimal solution?

When using A* (or any other best path finding algorithm), we say that the heuristic used should be admissible, that is, it should never overestimate the actual solution path's length (or moves). How ...
29 views

Longest simple walk below a certain weight

Given a directed graph G and a starting vertex $v$ and a cutoff weight $w$, I want to find a simple walk with net weight < $w$ that visits as many nodes as possible. Currently, I have a recursive ...
138 views

Travelling Salesman problem using Guided Local Search

I am doing Week_4 of https://www.coursera.org/learn/discrete-optimization/ stuck in solving TSP. As there are a lot of methods to solve this problem, I am currently coding Guided Local Search as ...
24 views

Defining Local Search stopping criteria

When performing a local search, for example, a 2-node exchange in a metaheuristic (like GRASP), what is the usual stopping criteria for that procedure? Some bibliography says that the local search ...
36 views

MAC-AC3 algorithm puts arcs in queue

I am studying Csp and I don't understand the line no 1.1 . Does queue contains all arcs or not?Explain with me 4-queens please. ...
157 views

How MAC-3(maintaining arc consistency-3) algorithm works?

I am studying CSP problems in artificial intelligence. I don't understand the MAC-3 algorithm especially line number 10. Could you tell me with step by step? ...
129 views

Optimal partitioning of n-tuples

Motivation Recently I was trying to optimize some API calls and reduced the problem to optimization of a cumulative number of identifiers across all the requests. I put some considerable effort into ...
671 views

Aren’t most constraining variable and least constraining value the exact opposite?

So aren’t MCV and LCV the exact opposite?MCV tries to choose the variable with the most constraints on remaining variables but LCV is opposite: it tries to rule out as least values for other variables ...
73 views

Choosing heuristic for A* algorithm where cost is less than absolute distance

Looking for information on choosing a heuristic for instances where the cost of traversing an edge can be less than one. For example, say movement is allowed in the cardinal directions. Should all ...
46 views

How to perform local search to find maximal induced subgraphs?

I'm looking for efficient ways to perform local search to find maximal induced subgraphs that satisfy certain properties : a tree, a forest or a bipartite subgraph for example. What I mean by local ...
22 views

Relevance of the ZeroSum game to Heuristic search?

A question was posed to me as to the relevance of the ZeroSum game to Heuristic search algorithms. I know that the zero sun game is a theory in which one persons gain is exactly balanced to another ...
16 views

Can Heuristic repair algorithm be applied to TSP?

Can Heuristic repair algorithm (or it's modification) be applied to Traveling Sales Person problem ? My gut feeling is that it can. But I have no idea - what cost(s)/conflicts should be minimized. ...
34 views

can someone provide a good resource for understanding 2 opt heuristic?

I have looked into wikipedia and this MIT slide. A step by step iteration of the algorithm with a clear example would be appreciated.
259 views

8 puzzle admissible heuristic where tiles are in correct position

For the 8 puzzle problem, it has been proved that if h(n) = number of tiles on wrong place. h(n) is an admissible heuristic as every tile which is in wrong place must be moved out at least once. But ...
29 views

How many states are examined in the most wins heuristic for tic-tac-toe (9-grid)?

I'm new to AI, and have a hard time to understanding how to count the total states are examined in the most wins heuristic for tic-tac-toe two plys deeper(9-grid)? Need help
118 views

How to prove if a heuristic function is admissible or not

Can somebody tell me how to solve this problem?
300 views

Nearest Insertion Traveling Salesman Heuristic: is it faster to insert nearest nodes first?

I am trying to implement the nearest insertion TSP heuristic. However, I am wondering if it matters which node I insert into the subgraph first. For example, should I start with one node; calculate ...
325 views

A* Search Algorithm Implementation with Priority Queue

I've got a question regarding the A* search algorithm's implementation. According to Wikipedia, one has to use a priority queue for retrieving the next node with the lowest f value, is it possible to ...
109 views

Does domination rule apply for inadmissible heuristics?

Let's say $h_1(n) \geq h_2(n)$ so that dominance is established even if $h_1$ and $h_2$ are both inadmissible/non-optimal heuristics -in whichever given search space. Is $h_1$ still faster/better ...
422 views

Does this A-Star heuristic already exist?

I've been thinking about the A* algorithm recently. For context, A* is a graph-navigating algorithm most often used to solve problems that go "What is the shortest path from point A to point B?". It's ...
50 views

Optimization Problem when calculating fitness is expensive

I need to solve an optimization problem, maximizing fitness in a set of around 1 million solutions. Calculating the fitness of any solution is very time consuming, taking around 5 minutes. Therefore, ...
38 views

Steps to create a heuristic for solving a problem

I am completely new to AI and doing self-learning to acquire this knowledge. I went through the different available search algorithm like BFS, DFS and A* but something that I can't understand is a ...
23 views

Justification behind this heuristic in SMA*+

I'm reading the paper Enhanced Simplified Memory-bounded A Star (SMA*+). In short, the authors propose a limited-memory version of A* where we cull nodes if we are out of memory, to re-expand them ...
32 views

What is the peak in fitness landscape

I have just started reading about fitness landscapes and I couldn't understand what the peak means. What does the peak mean?
154 views

SAT Solving + Turing Machines

I have a couple of questions based on how SAT solvers work. I understand that SAT solvers may employ any/all of the following techniques: Randomness Heuristics Backtracking SAT is just one example ...
100 views

Improvement Heuristics for Asymmetric TSP

i have been solving the Time-Dependent Traveling Salesman Problem using an Ant Colony Optimization. Upon reading the ACO papers, there are several reminders which state that ACO performs best with ...
195 views

Consistent heuristic and A*

The following graph has consistent heuristic. An A* algorithm will alter its first guess ACD to the correct shortest path ABD... if it has consistent heuristic, doesnt it mean, that AB should be ...
18 views

How to get initial flow for TSP with missing edges

I need to solve a version of the traveling salesman problem with missing edges. I've decided to use simulated annealing. How do I generate a valid initial path effectively? I would use a greedy ...