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4

The term incidence matrix has caused confusion on this site before, so I think it's time to clear this up. There's no standard, generally agreed upon definition of incidence matrix. It's a loose term for a matrix that describes the relationship (connections) between two different classes of objects. What these objects are can vary. When you see the term ...


3

The answer why it is not valid incidence matrix is given by the above answers. To verify if your matrix is valid, use the following command m = {{1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0}, {1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0}, {1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1}, {0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0}, {0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0}, {0, 1, 0, 0, 1, 0, 0, ...


3

The test matrices are matrices but not incidence matrices. The rows represent the vertices and each column represents an edge. Consequently each column must have only 2 non-zero entries or a single entry of 2 for self loops. This is not the case for any of the matrices or their transposes. To check for yourself, try yourself, e.g.: mat = ...


3

Sorry, but your matrices aren't valid incidence matrices. From the IncidenceMatrix help page: For an undirected graph, an entry $a_{ij}$ of the incidence matrix is given by: 0 if vertex $v_i$ is not incident to edge $e_j$ 1 if vertex $v_i$ is incident to edge $e_j$ 2 if vertex $v_i$ is incident to edge $e_j$ and a self-loop In ...


3

For the aid of anyone else who runs into this issue I seem to have figured out the compounding factors necessary to recreate this problem. Create a Windows directory C:\foo\bar Save arbitrary Notebook example.nb to this directory Using the Option Inspector add to NotebookPath exactly: "C:\\foo\\bar" Close and restart Mathematica Create a new Notebook and ...



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