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8 votes
0 answers
459 views

Extension of Erdős-Gallai (s,t)-path theorem to directed graphs

The following is a result of Erdős-Gallai from 1959 (https://link.springer.com/article/10.1007/BF02024498): Given a 2-connected undirected unweighted graph with minimum degree at least $d$, for every ...
Nicole Wein's user avatar
6 votes
0 answers
218 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 ...
Gordon Royle's user avatar
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5 votes
0 answers
99 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 ...
joro's user avatar
  • 25.4k
3 votes
0 answers
109 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?
Kristaps John Balodis's user avatar
2 votes
0 answers
111 views

Constructing Hamiltonian circuits in acyclic digraphs

Any directed graph $G$ lacking cycles can acquire a Hamiltonian circuit through the addition of a sufficient number of edges. Q. Is there a method to minimize the addition of edges to achieve a ...
ABB's user avatar
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2 votes
0 answers
83 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}...
Turbo's user avatar
  • 13.9k
1 vote
0 answers
93 views

15-game graph contains a Hamiltonian path ? Lovász conjecture for groupoids, loops, quasigroups , etc?

Typically Cayley graphs are defined for groups and generators sets S. But basically one only needs some set S and another set V and partially defined operation SxV->V, then one defines graph with ...
Alexander Chervov's user avatar
1 vote
0 answers
338 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&...
skytect's user avatar
  • 139
1 vote
0 answers
186 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 $(\...
Dominic van der Zypen's user avatar
0 votes
0 answers
29 views

Explicit Bound in Draganić's Hamiltonicity Result?

Earlier this year, Draganić et al published a remarkable piece of work that resolved Krivelevich and Sudakov's conjecture on the Hamiltonicity of expanders. Here's the abstract: An n-vertex graph G ...
Bill Bradley's user avatar
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0 votes
0 answers
97 views

Relation of minimum spanning trees to the shortest Hamiltonian path problem

Spanning trees can be decomposed into a minimal set of maximal path graphs, whose vertices have degree two exactly if they also have degree two in the spanning tree; lets call these paths tree paths. ...
Manfred Weis's user avatar
  • 13.2k