Daily tweets about networks, graph theory, and related topics from @JohnDCook
Joined July 2013
- Tweets 4,235
- Following 19
- Followers 46,320
- Likes 10
221 Photos and videos
Jun 12
Ten things you (possibly) didn’t know about the Petersen graph cp4space.wordpress.com/2013/…
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Jun 10
The eccentricity of a node v is the maximum distance from v to all other nodes in the graph.
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Jun 8
A graph is chordal if every cycle of length >3 has a chord (an edge joining two nodes not adjacent in the cycle). en.wikipedia.org/wiki/Chorda…
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Jun 5
If A is the adjacency matrix of a graph, the trace of A³ is six times the number of triangles in the graph.
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Jun 4
The characteristic polynomial of a graph is the determinant of xI - A where A is its adjacency matrix.
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Jun 3
Given a list of numbers, when can you construct a simple graph whose nodes have those degrees? en.wikipedia.org/wiki/Erd…
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Jun 2
Modularity in a network is a measure of the degree to which nodes associate with like nodes. en.wikipedia.org/wiki/Modula…
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May 29
The eigenvector corresponding to the second smallest eigenvalue of the Laplacian is called the Fiedler vector.
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May 28
Hitting time is asymmetric. Commute time c(i, j) = h(i -> j) h(j -> i) is symmetric.
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May 27
The hitting time h(i -> j) is the average number of steps to walk from node i to node j where probability is proportional to edge weight.
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May 25
The reciprocity of a graph is the proportion of edges that are reciprocated.
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May 22
In a directed graph, an edge from i to j is reciprocated if there is also an edge from j to i.
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May 21
The betweenness centrality of a point is the number of geodesic paths that pass through the point.
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May 20
The Petersen graph serves as a counterexample to many would-be graph conjectures. en.wikipedia.org/wiki/Peters…
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