Questions tagged [traveling-salesman]

The Traveling Salesman Problem and variants

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11 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 ...
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1answer
23 views

Question about complexity of TSP Optimization problem

Is this statement true? Optimization TSP problems are known to be NP-hard, as we do not have a minimum cost to compare against, and in order to verify a solution is optimal, we need to iterate ...
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For what applications of the traveling salesman problem, does visiting each city at most once truely matter?

Traditionally, the traveling salesman problem has you visit a city at least once and at most once. However, if you were an actual traveling salesman, you would want the least cost route to visit each ...
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82 views

TSP Variant — Colored Path

Recently I came up with a traveling-salesman-esque problem. As usual, we have $n$ vertices, and a weighted edge between any two vertices. However, each vertex is associated with a color, which may be ...
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1answer
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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 ...
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1answer
195 views

Hamilton Circuit

The Dirac's theorem states that: "For a Graph G with N vertices, if the degree of each vertex is atleast N/2 then, the Graph has a Hamilton Circuit." Can the same be said if a graph has a Hamilton ...
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1answer
47 views

Given n sets of points in the plane find the shortest path which passes from exactly one point from each set

I am trying to find an algorithm for this. You can imagine each set $(S_1, S_2, \ldots, S_n)$ as points with different colour. Also it isn't necessarily $|S_1|=|S_2|=\cdots=|S_n|$. For $n=1$ we ...
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3answers
105 views

How to compute number of possible paths in directed Traveling Salesman problem?

If we have directed modification of TSP, so that some routes are possible in one direction, given directed graph, could you compute number of possible tours? What if we have supercomputer, does it ...
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1answer
26 views

Dubins TSP NP-hardness proof detail

In Le Ny et al.'s paper On the Dubins Traveling Salesman Problem (https://tinyurl.com/y59f7d8x) the authors prove, among other works, that the Dubins Traveling Salesman Problem (DTSP) is NP-hard. I ...
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1answer
50 views

Travelling Salesman: Big O Complexity when starting city is fixed

We are studying the Travelling Salesman problem in my high school class, and I am wondering what the Big O complexity of the TSP is when you MUST start and end at the same city. For example, given 4 ...
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17 views

Number of Solutions for Brute Force Algorithm of Travelling Salesperson Problem

We are learning about the travelling salesperson problem in my high school class and we are discussing how computers could solve for the problem, even though the problem is intractable, using a brute ...
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TSP with knapsack combo

My problem statement is that my agent has to visit multiple pickup points once to collect orders, say Item A, Item B, Item C...... etc. We are using TSP for that. Now say Item A are stored in 3 ...
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1answer
27 views

Dubins TSP crossing trajectory theorem

In the Dubins TSP (DTSP for short), one needs to visit a set of given points in the plane, and return to the starting point, minimizing the distance of such a trajectory. The difference with the ...
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1answer
35 views

Why isn't the search space size of TSP $(n-1)!$ instead of $n!$?

I'm just learning about the travelling salesman problem, and I've been playing around with it. I'm not sure if what I've found is just a special case or not. My professor says the search space size is ...
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1answer
33 views

Approximation algorithm to visit all nodes in an undirected, weighted, complete graph, with shortest sum of edge weights

I'm looking for an algorithm that gives a smallest value of 'travel cost' within the following constraints: a complete, connected, weighted graph, vertices are defined in 3d euclidean space, ...
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2answers
68 views

What is the graphic TSP?

I'm not sure if I understand the following definition of the (well-known apparently) Graphic TSP, also known as graph-TSP : ...graph-TSP, that is, the traveling salesman problem where distances ...
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League and Divisions problem (np-hard)

There is a League. And there are Divisions, that are the disjoint subsets of this League. There are n teams (unique locations are given, let's assume it's x and y for simplicity reasons). Every team ...
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Traveling Salesman Problem with profit and time limit as ILP formulation

How to formulate the following problem? The salesman gains a profit $p_{i}$ when visiting a city i, trip between city i and city j costs $c_{ij}$ and takes $t_{ij}$ time. The trip must not exceed a ...
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Delivering to two or more locations in one go while respecting deadlines?

Assume that I have a business where people can place product orders. Each order must be delivered within a time limit, say $x$ minutes. I need 15 minutes to make each product. However, multiple ...
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2answers
365 views

Linear Path Optimization with Two Dependent Variables

Alright, so this is a fairly interesting problem I have but also slightly difficult to explain so I will try my best. There are two runners on a line that goes from $x=0$ to $x=100$. The two runners ...
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1answer
42 views

A problem to maximize the number of edges in a cycle while minimizing the total weight

I encountered the problem below and the only solution I came up with is branch and bound like that is used in TSP and I don’t think the bound I used is good enough. Are there any better idea on this? ...
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529 views

Is there an efficient solution to the travelling salesman problem with binary edge weights?

Is there a way to solve TSP in polynomial time if there are only two kinds of weights, 0 and 1?
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If I can solve Sudoku, can I solve the Travelling Salesman Problem (TSP)? If so, how?

Let us say there is a program such that if you give a partially filled Sudoku of any size it gives you corresponding completed Sudoku. Can you treat this program as a black box and use this to solve ...
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1answer
75 views

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 ...
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128 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 ...
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1answer
204 views

2-opt vs 3-opt comparison

I have a question regarding performance of 2-opt and 3-opt algorithms. I tried implementing the 3-opt and 2-opt algorithms and most of the time 3-opt outperforms the 2-opt algorithm around 5%. ...
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1answer
69 views

Is TSP a more detailed form of the “Set Inclusion” question?

Background Set Inclusion GIVEN: set of cards, some with blue backs, and each with a positive, integer face value. QUESTION: Are there any [blue-backed cards] with a [face value <= L]? 2 ...
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2k views

Which of the following statements are true for the given special cases of the Traveling Salesman Problem?

I'm taking the Algorithms: Design and Analysis II class, one of the questions asks: Which of the following statements is true? Consider a TSP instance in which every edge cost is either 1 ...
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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. ...
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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.
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Solve this integer program (problem: Travelling salesman problem)

How do one solve the following integer program? $$ \begin{align*} \text{minimize} \quad &\sum_{(i,j) \in E} d_{ij} x_{ij} \\ \text{subject to} \quad & \sum_{j \in V} x_{ij} = 2 \;\; \forall i ...
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268 views

Clarify the steps: what happened in this mathematical modelling of TSP?

Source: http://examples.gurobi.com/traveling-salesman-problem I don't get this part: (look at the source) $$\sum_{i,j\in\{1,2,3\},i\neq j} x_{ij}=3>2=|\{1,2,3\}|-1$$ I get that $x_{ij}$ is ...
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Mathematical modelling on Christofides algorithm

Does a mathematical modelling on Christofides algorithm exist, is it even possible to create one?
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1answer
280 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 ...
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2answers
91 views

How to Solve TSP Given Length of Path?

I am trying to devise an algorithm in which given the length of a path that satisfies the constraints of the Traveling Salesman Problem, I can find the path. Currently, my only solution is to find a ...
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1answer
276 views

Christofides algorithm (by hand)

I am following this algorithm example: https://en.wikipedia.org/wiki/Christofides_algorithm#example The graph: [![enter image description here][1]][1] ...
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1answer
68 views

Do you >have< to define the upper and lower bound? (context: traveling salesman)

Do one have to define the upper and lower bound to be able to solve the tsp, or is that just an unnecessary intermediate step? And if so, why would one define those bounds? (context: the traveling ...
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1answer
55 views

Grid Based DP: How do we tweak the Travelling Salesman Problem to work with Grids

The question is: There is a n x n grid (Maze) which has either 0, 1 or 2. 0 means a path exists, 1 means the cell is blocked and 2 means there exists gold in that cell. Task is to start from 0,...
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Shortest route through ordered points

My algorithm-fu is really weak and I do not know how to express following problem in terms of any other problem known to me: Given a small rectilinear grid and coordinates of four cells in this grid (...
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105 views

Is there a solution for this maze problem in polynomial time?

Suppose you have a maze represented by a graph where each vertex represents a room and edges represent paths between rooms and each edge has a weight denoting the time it takes to go that way. Now ...
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Does there exist a travelling salesmen generating algorithm?

I'm curious if somebody has already figured this out. Is there an efficient algorithm that will generate (in $\mathbb{R}^2$) a sequence of points in such a way that the solution to the travelling ...
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267 views

Minimum weight Hamiltonian path on a weighted (0 and 1) tournament graph

Suppose we have a weighted tournament graph. (A directed graph in which every pair of distinct vertices is connected by a single directed edge.) The weights are constrained to be 0 and 1. I know ...
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1answer
197 views

Why does Travelling Salesman Problem pose the restriction that each vertex can only be visited once?

According to the wiki page of TSP as a graph problem, It is a minimization problem starting and finishing at a specified vertex after having visited each other vertex exactly once Then what if a ...
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1answer
162 views

Reducing closed TSP to open with fixed starting vertex

I have implemented a branch and bound algoritm for finding a Hamiltonian cycle in my software, but I actually need to find a shortest route from fixed vertex through all verticies ending at any of ...
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21 views

Partial TSP in Euclidian plane

I'm interested in the following variant of Travelling Salesman Problem sometimes called Partial TSP. I'm particulary interested in the euclidian version : Input : A set $\{x_1,\dots,x_n\}\subset \...
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In the Traveling Salesperson Problem, is the shortest tour the same regardless of the start/return city? How do you prove it?

This is the form of the problem where you start at a city, visit every other city, and return to the start city. Since you "return" to every city in the completed cycle, it seems intuitive that the ...
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1answer
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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 ...
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77 views

Comparison of time-dependent traveling salesman heuristics

I'm looking into implementing a heuristic for the time-dependent traveling traveling salesman problem (TDTSP) that completes in a certain amount of time. There are a wide range of possible ways to ...
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2answers
351 views

if traveling salesman problem is decidable in polynomial time, can an actual solution be proposed in polynomial time?

I'm asking because it seems that P problems refer to decision problems rather than actually propose a solution.
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95 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 ...