Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 2233

A Hamiltonian graph (directed or undirected) is a graph that contains a Hamiltonian cycle, that is, a cycle that visits every vertex exactly once.

10 votes
Accepted

How many hamiltonian cycles can be removed from a complete directed graph before it becomes ...

I will rephrase your question slightly. Let $K_{n}^{*}$ be the directed graph with $n$ vertices and two oppositely directed edges for each pair of vertices. Your question is then the following. …
Tony Huynh's user avatar
  • 32.1k
9 votes

What is the smallest uniquely hamiltonian graph with minimum degree at least 3?

I am not sure what the smallest such graph is, but since you also asked for more information on uniquely hamiltonian graphs with minimum degree $3$, Entringer and Swart proved the following nice theor …
Tony Huynh's user avatar
  • 32.1k
6 votes

Efficient Hamiltonian cycle algorithms for graph classes

One class of graphs for which many NP-hard problems (including finding a Hamiltonian cycle) are easy (linear-time) are graphs of bounded tree-width. Indeed, by Courcelle's theorem any problem which c …
Tony Huynh's user avatar
  • 32.1k
5 votes
Accepted

Approximation of Hamiltonian cycles

Claim. For every $\rho \geq 1$, there is no polynomial $\rho$-approximation algorithm for $\texttt{MinHalfSimpCycle}$, unless P=NP. Proof. Let $G$ be an instance of the Travelling Salesman Problem (TS …
Tony Huynh's user avatar
  • 32.1k
4 votes
Accepted

Hamiltonian cycle in $S_n$ with transpositions

Yes, $(S_n, E_n)$ contains a Hamiltonian cycle for every $n \geq 3$. This follows by the Steinhaus–Johnson–Trotter algorithm . The transpositions can even be chosen to be consecutive elements in the …
Tony Huynh's user avatar
  • 32.1k
3 votes
Accepted

Does this graph contain at least two Hamiltonian cycles?

Here is a proof of Gordon's claim. We will prove something slightly stronger. Claim. Let $G$ be a $d$-regular graph with $d$ odd. Then for every $e \in E(G)$, there is an even number of Hamiltoni …
Tony Huynh's user avatar
  • 32.1k
3 votes

How to efficiently find a Hamiltonian cycle in a graph whose closure is complete?

In the case that your graph satisfies the conditions of Ore's theorem (so that it's Ore closure is $K_n$ after 'one step'), there is an easy algorithm to find a Hamilton cycle. Arbitrarily arrange …
Tony Huynh's user avatar
  • 32.1k