Questions tagged [hamiltonian-paths]

paths on a graph that visit each vertex exactly once

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9 votes
2 answers
1k views

Is this graph Hamiltonian?

Let $G$ be a simple $2$-connected graph with $m+n$ vertices ($n>m \geq 3$) with degree sequence $(m-1)^m$, $(n-1)^n$; that is, $G$ is degree-equivalent to two disjoint cliques $K_m$, $K_n$ of ...
2 votes
1 answer
70 views

Hamiltonian path in divisibility graph

Let $\mathbb{N}$ denote the set of positive integers, and consider the graph $(\mathbb{N}, E)$ where a set $\{a,b\}$ of two distinct positive integers belongs to $E$ if there is an integer $k>1$ ...
6 votes
2 answers
273 views

Hamiltonian path in bike-lock graph with $1$ known digit

Motivation. My youngest son has a bike lock with dials, and he forgot the unlocking combination completely, except that he remembered that digit $0$ appeared somewhere in the combination. So it was my ...
-1 votes
2 answers
97 views

Path of length $n$ but no Hamilton cycle [closed]

What is an example of a simple graph $G = (\{1,\ldots,n\}, E)$, where $n\in\mathbb{N}$ is a positive integer, with the following properties? There is a path in $G$ of length $n$, every vertex has at ...
4 votes
2 answers
172 views

Hamilton cycles in $\{0,1\}^n$ with fixed Hamming distance

Let $n>1$ be an integer. For $a,b\in \{0,1\}^n$ let $d_h(a, b)$ denote the Hamming distance of $a$ and $b$. For $k\in \{1,\ldots,n-1\}$ let $H(n,k)$ be the graph on $\{0,1\}^n$ given by the edge ...
6 votes
0 answers
100 views

Maximum number of Hamilton paths in a tournament on $n$ vertices

Recall that a tournament is a directed graph $T$ such that for every pair of distinct vertices $\{v,w\}$, exactly one of the ordered pairs $(v,w)$, $(w,v)$ is an arc of $T$. A tournament is strongly ...
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1 vote
0 answers
98 views

Heuristics for minimum path cover of undirected graph

Suppose you would like to find a set of paths on an undirected connected graph that ensures every vertex is visited exactly once while minimising the number of paths used. In this case, a "path&...
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13 votes
1 answer
455 views

Generalisation of this circular arrangement of numbers from $1$ to $32$ with two adjacent numbers being perfect squares

I posted this question on MSE, and failed to get the type of answer I wanted. That's why I would like to post it here and wait for the experts to reply. Here's the link to the MSE post, which I ...
0 votes
0 answers
140 views

Number of open tours by a biased rook on a specific $f(n)\times 1$ board which end on a $k$-th cell from the right

We have a simple structure - biased rook of the two types. Biased rook of the first kind which make open tours on a specific $f(n)\times 1$ board where $f(n) = \left\lfloor\log_2{2n}\right\rfloor + 1$ ...
1 vote
1 answer
92 views

How to construct a hamilton-connected cubic graph? Is it possible?

If we are given a large integer $k$, can we construct a hamiltonian-connected $n$-vertex graph for every even $n\geq k$ such that all its vertices are of degree 3? Is there any reference concerning ...
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1 vote
2 answers
124 views

Hamiltonian cycle in $S_n$ with transpositions

For any set $X$, let $[X]^2=\{\{a,b\}:a\neq b \in X\}$. If $n\in\mathbb{N}$ is a positive integer, let $S_n$ denote the collection of bijections $\varphi:\{0,\ldots,n-1\}\to\{0,\ldots,n-1\}$. Let $E_n\...
1 vote
1 answer
55 views

Graph with two edge-disjoint Hamiltonian paths between the same vertex-pair

Provided existence, what is the smallest graph $G(V,E)$ with two edge-disjoint Hamiltonian paths between $u$ and $v;\ \lbrace u,v\rbrace\subset V$?
  • 11.3k
2 votes
1 answer
135 views

Directed version of this lemma

On a paper by Shoham Letzter, available Here, there's a lemma that says as follows: Lemma 0: For every graph $G$, there exist two disjoint sets $U,W\subseteq V(G)$ of equal size, such that there are ...
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1 vote
1 answer
153 views

Algorithm for multiple travelling salesmen problem with given starting point and end point

Given: Set of n>0 cities is to be traversed by m>0 salespeople Where all the salespeople: Are positioned at the same starting city; Finish at a same destination (which different from starting ...
  • 11
0 votes
1 answer
105 views

Sources of information on algorithms for finding Hamiltonian cycles (Pósa)

I research various algorithms in complex networks and I am quite new in this field. I am currently focusing on random geometric graphs - Pósa's algorithm for finding a hamiltonian cycle. Can you ...
  • 1
7 votes
3 answers
2k views

"Gray code" for building teams

Motivation. In a team of $n$ people, we had the task to build subteams of a fixed size $k<n$ such that every day, $1$ person of the subteam is replaced by another person in the team, but not in the ...
2 votes
0 answers
74 views

Zero-One law for Hamiltonian path subgraphs of Hamming Distance Graphs?

$(\alpha,\beta,d)$-Hamming Distance Graph $G_d(\alpha,\beta)$ for $\alpha,\beta\in(0,1]$ is a graph on $2^d$ vertices $v_0,\dots,v_{2^d-1}$ with edges $(v_i,v_j)\in\mathcal E(G_d)$ iff $0<\sum_{t=1}...
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4 votes
1 answer
163 views

Hamiltonian paths on the space of graphs

Disclaimer: I am not a professional graph theorist. Motivation: Let's consider the set $G_N$ of graphs with $N$ vertices where the vertices are assumed to be distinguishable. This set may ...
  • 3,503
5 votes
1 answer
202 views

Integers with a Hamiltonian Square Path

Let $n>1$ be an integer and set $[n]=\{1,\ldots,n\}$. We say that $n$ has a "Hamiltonian Square Path" if there is a bijection $\varphi:[n]\to[n]$ such that for all $k\in [n-1]$ we have that $\...
2 votes
0 answers
163 views

What is the relation between the different generating functions thought as finite approximations of action functionals

In the book Introduction to symplectic topology by MC Duff and Salamon, a discrete analogue of the action functional is defined on $\mathbb{R}^{2n}$. The idea is that a Hamiltonian isotopy can be ...
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6 votes
1 answer
294 views

Are Gray codes in $\{0,1\}^n$ isomorphic?

Let $n\in\mathbb{N}$ be a positive integer. Two elements of $\{0,1\}^n$ form an edge if and only if their Hamming distance equals $1$. It is known that $\{0,1\}^n$ endowed with this graph structure ...
-1 votes
1 answer
638 views

Find all paths on undirected Graph [closed]

I have an undirected graph and i want to list all possible paths from a starting node. Each connection between 2 nodes is unique in a listed path is unique, for example give this graph representation:...
2 votes
1 answer
109 views

$\omega$-Hamilton paths in $\mathbb{Z}^n$

For any set $X$ set $[X]^2 = \{\{x,y\}: x,y\in X, x\neq y\}$. If $n\geq 2$ is an integer, we endow $\mathbb{Z}$ with a graph structure in the following way. If $x,y\in \mathbb{Z}^n$ we say $x,y$ are ...
1 vote
1 answer
107 views

Sub-circle-free Christmas-gift-giving

Suppose there is a group of $n$ people giving gifts to one another. Everybody brings a gift but we want the gifts to be "well-distributed" in the group. By this I mean the following: In how many ...
1 vote
1 answer
279 views

Hamiltonian cycles -- Partition function

Assume a complete undirected graph $G'=(\mathcal{V}',\mathcal{E}')$ and the partirion function: $$\sum_{\boldsymbol{x}\in \{-1,+1\}^n} \prod_{\left(i,j\right)\in \mathcal{E}'} \left[1+x_{i}x_{j}\...
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1 vote
0 answers
62 views

Reintegration Method for Shadow Removal

I'm not sure if this is an appropriate question for stack overflow or for math overflow, so please point me in the right direction if I'm in the wrong place. I am trying to implement shadow removal ...
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3 votes
1 answer
544 views

Tournaments with exactly one directed Hamiltonian path

Every tournament contains a directed Hamiltonian path (a path visiting every vertex exactly once). Suppose that $T$ is a tournament on $[n]:=\{1,\ldots,n\}$ for some integer $n\geq 2$ with exactly ...
1 vote
0 answers
182 views

Countable graph that is "as non-traceable as it gets"

If $\omega$ denotes the set of the natural numbers (= the first infinite ordinal), and if $E\subseteq\binom{\omega}{2}$ is any subset, we call a map $f\colon\omega\to\omega$ a walk in the graph $(\...
1 vote
2 answers
260 views

Hamiltonicity and minimal degree in bipartite graphs

Given an integer $k>1$, is there a connected bipartite graph $\Gamma = (A, B, E)$ where $A\cap B = \emptyset$ and $E \subseteq \big\{\{a, b\}:a\in A, b\in B\big\}$ such that $|A| = |B|$, $\text{...
1 vote
3 answers
628 views

Hamiltonian paths in bipartite graphs with 2 sets of "almost" same cardinality

Suppose we have two finite disjoint sets $A, B \neq \emptyset$ such that $|A|$ and $|B|$ differ by at most $1$, and let $\Gamma = (A\cup B, E)$ where $E\subseteq \big\{\{a,b\}: a\in A, b\in B\big\}$ ...
8 votes
2 answers
1k views

"Gray code" of all permutations

Informally asking, can we step through all permutations of the set $\{1,\ldots,n\}$ by just using transpositions? More formally: For any $n\in\mathbb{N}$ let $[n] = \{1,\ldots,n\}$ and let $S_n$ be ...
6 votes
1 answer
87 views

Existence of a 2-labelled Hamiltonian Path decomposition of $K_{2n}$

I am trying to see if, for the complete graph $K_{2n}$, there exists a labelling of the vertices with two labels $a$ and $b$ (each used exactly $n$ times), such that we can decompose the graph into $n$...
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1 vote
1 answer
75 views

Graph gadget related to uniquely hamiltionian regular graphs (question #2)

Related to uniquely hamiltionian graphs. For natural numbers $a,b$ define $(a,b)$ gadget $G$: $G$ is finite simple graph. Two vertices $u,v$ are of degree $b$ and the rest of the vertices are of ...
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5 votes
0 answers
85 views

Graph gadget related to uniquely hamiltionian regular graphs

A graph is uniquely hamiltonian if it has exactly one hamiltonian cycle. According to a conjecture there are no $r$-regular uniquely hamiltonian graphs for $r > 2$ and of special interest is the ...
  • 23.6k
5 votes
1 answer
316 views

The minimum number of Hamiltonian paths in a strongly connected tournament of order $n$

For $n\ge3$ let $a(n)$ be the minimum number of Hamiltonian paths in a strong (i.e., strongly connected) tournament of order $n.$ Where is $a(n)$ discussed in the literature? Is the exact value ...
  • 8,771
3 votes
0 answers
91 views

Number of Hamiltonian paths in the Hoffman-Singleton graph/Moore graphs?

Does anyone happen to know how many Hamiltonian paths are in the Hoffman-Singleton graph, or have any idea on how I could count such paths?
11 votes
1 answer
2k views

The number of Hamiltonian paths in a tournament

If $h(T)$ denotes the number of (directed) Hamiltonian paths in the tournament $T,$ what is the range of $h(T)$ as $T$ ranges over all (finite) tournaments $T$? By a classical theorem of Rédei (...
  • 8,771
2 votes
1 answer
1k views

Can we solve Hamiltonian Path problem for biconnected planar graphs in linear time?

Assume that we have a bi-connected planar graph $G$ with $\Delta(G)>3$, and we want to find a Hamiltonian Path in $G$. As we know the st-order of a bi-connected planar graph can be computed in ...
1 vote
1 answer
96 views

Hamiltonian Path through $n$-bit strings with maximum number of $0\mapsto 1$ transitions

Let $G_n$ be the complete graph whose vertices are the $2^n$ $n$-bit strings. Let $H_n$ denote the Hamiltonian path through $G_n$ that uses the maximum number of edges that correspond to a single bit ...
11 votes
3 answers
1k views

Square filling self avoiding walk

I want to create an algorithm that fills a square grid with a random Hamiltonian path starting at a particular point. See this example. One approach is to try a free direction as a next step, and ...
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8 votes
0 answers
612 views

How many ways can a snake lie?

This is essentially a question about counting nonintersecting short paths in a cubic lattice, but with a twist. (One constraint that I did not make clear below is that when to turn is already chosen:...
7 votes
1 answer
472 views

Paths in groups

Given a finite group $G$, write $K(G)$ for the complete digraph on the elements of $G$. Label the edge from $g$ to $h$ by element $g^{-1}h$. Question: For what groups does there exist a Hamiltonian ...
19 votes
5 answers
724 views

Hamiltonian paths where the vertices are integer partitions

I have been working on this problem for several months now but have not made much progress. It concerns the set of all integer partitions of n. Let the vertices of the graph G=G(n) denote all the p(n) ...
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