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1 vote
0 answers
113 views

Existence of Euler $uv$-path $\iff$ all vertices except possibly u,v are even

A statement in my course says that : “A connected graph $G$ contains an Euler $uv$-path if and only if all vertices except possibly $u,v$ are even.” I agree with the $\implies$ direction, but in the ...
Kilkik's user avatar
  • 1,952
0 votes
0 answers
89 views

The only cut vertex in a graph

Let a graph $G$ be arbitrarily traversable from a vertex $v$, i.e., any trail in $G$ initiatng from $v$ ultimately results in an Eulerian $v-v$ circuit. Let $v$ be a cut-vertex in $G$. Is it true that ...
karparvar's user avatar
  • 5,782
0 votes
2 answers
1k views

Determine if edge is a bridge in a graph

I would like to implement Fleury’s algorithm to find Eulerian trails in a graph. This algorithm requires me to tell if a given edge is a cut edge (bridge). Is there a more effective way of doing this ...
Károly Pákozdi's user avatar
2 votes
2 answers
841 views

Is Eulerian graph necessarily connected?

If a graph is Eulerian (i.e. has an Eulerian tour), then do we immediately assume for it to be connected? The reason I ask is because I came across this question: Graph and its line Graph that both ...
user356's user avatar
  • 467
3 votes
2 answers
1k views

Eulerian graph has three vertices of the same degree

Let $G$ be a connected graph with $n \ge 3$ vertices. Prove that if $G$ has an Euler Cycle than it has 3 vertices of the same degree. I thought using the Pigeonhole principle but I'm not sure how... ...
hemi's user avatar
  • 227
1 vote
2 answers
53 views

Proving the graph $V=\{S\subset\{1,2\ldots9\}\mid3\leq\left|S\right|\leq4\},\,\,\,E=\{(u,v)\mid u\subset v\}$ is connected

Let $G=\left\langle V,E\right\rangle$ be an undirected graph with $V=\left\{ S\subset\left\{ 1,2,\ldots,9\right\} \mid\left|S\right|\in\left\{ 3,4\right\} \right\}$ and $E\left\{ \left(u,v\right)\mid ...
H.Rappeport's user avatar
  • 1,546
0 votes
0 answers
287 views

Alternating path from any vertex to any vertex [duplicate]

Statement: Given a connected graph with all edges coloured in one of two colours (red and black), so that for each vertex the number of incident red edges is equal to the number of black edges. Proof:...
Dmitriy Baranov's user avatar
0 votes
1 answer
105 views

Question on graph Connectivity.

Question Consider the statement below-: $\text{1.In simple graph with 6 vertices,if degree of each vertex is 2 ,then graph is connected}$ $\text{2.In simple graph with 6 vertices,if degree of each ...
laura's user avatar
  • 2,540
1 vote
0 answers
57 views

Removing path of a connected graph. [duplicate]

I bumped into this question in an old exercice sheet : Let $ G = (V,E) $ be a connected graph with minimum degree $ \delta(G) = k \geq 2$. Prove that there exist a path $P = x_1x_2...x_k$ such that ...
Donno's user avatar
  • 153
2 votes
1 answer
1k views

The line graph of Eulerian and Hamiltonian graphs

If a graph $G$ is Eulerian then I can show that the line graph of $G$ is Eulerian but is the converse true ? If $G$ is Hamiltonian then I can show that the line graph of $ G$ is Hamiltonian but is ...
hali's user avatar
  • 285