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1 vote
1 answer
34 views

Worst Case Solution for directed Chinese Postman Problem

The Problem Let $G$ be a directed graph with $n$ vertices. How long is a shortest circuit that visits every edge in the worst case? That is how long is the solution to the directed Chinese Postman ...
Felix's user avatar
  • 11
-1 votes
1 answer
43 views

What are necessary and sufficient conditions to have a negative cycle in a directed graph with some negative edges? [closed]

Trying to test Johnson’s algorithm with over 100 vertices but it doesn’t work if there is a negative cycle. So I’m trying to write code to construct graphs with some negative weights (about 10% of the ...
Bark Jr. Jr.'s user avatar
3 votes
1 answer
190 views

How many ways of traversing every arc of a complete digraph exactly once from a given starting vertex are there?

Given a set of $n$ states $V = \{ s_1, s_2, \ldots, s_n \}$, and a complete digraph $G = (V, A)$ where $A = \{ (a,b) \mid (a,b) \in V^2\; \text{and}\; a \neq b \}$, I'm interested in finding cyclic ...
Florian Ragwitz's user avatar
0 votes
1 answer
35 views

Show that this graph is a tree

Suppose we have a directed multigraph (a graph with loops and parallel edges), with vertex set $V=\{v_1,v_2,\cdots,v_n\}$, such that $d^+(v_i)=d^-(v_i)$ for every $i=1,2,\cdots,n$, i.e. indegree of ...
QED's user avatar
  • 12.7k
0 votes
0 answers
36 views

Can a Graph be Proven to be Directional?

Here's a line from my textbook that I'm having trouble understanding: Let $G$ be a simple graph with $n$ vertices and $m$ edges. If $G$ is undirected then then $m\leq \frac{n(n-1)}{2}$, and if $G$ is ...
ayNONE's user avatar
  • 77
2 votes
0 answers
37 views

Digraphs with exactly one Eulerian Tour

I’ve been thinking about the following problem from Richard Stanley’s list of bijective proof problems (2009). There, this problem is said to lack a combinatorial solution. The problem is the ...
Luz Grisales's user avatar
1 vote
1 answer
441 views

How can I solve the Rotating Drum problem for 64 segments? (Or at all)

For clarification, I am very bad at maths and the logic usually goes right over my head, however I am studying a reasonably high level of maths because I am a software and game development student. I ...
Nerf_Herder42's user avatar
2 votes
1 answer
71 views

Upper bounds on the solution to a directed route inspection problem

If for any strongly connected digraph $D$ we define $\lambda(D)$ to be the length of any shortest closed walk traversing every arc in $D$, then does there exist some constant $m\in\mathbb{R}$ such ...
Ethan Splaver's user avatar
2 votes
1 answer
2k views

How to find Eulerian path in the given graph?

I have plotted the following graph (was given by the adjacency matrix): And I have to find the Eulerian path there and emphase this. I am concerned because my book says that the further action ...
M.Mass's user avatar
  • 2,672
0 votes
1 answer
5k views

What are the necessary and sufficient conditions for Euler path in directed graph?

The definition says "A directed graph has an eulerian path if and only if it is connected and each vertex except 2 have the same in-degree as out-degree, and one of those 2 vertices has out-degree ...
rahul sharma's user avatar
7 votes
2 answers
4k views

Does Eulerian cycle in digraph really need strongly connected component?

I read that a directed graph has an Eulerian cycle if and only if every vertex has equal in degree and out degree, and all of its vertices with nonzero degree belong to a single strongly connected ...
Võ Hoàng Trọng's user avatar