Consider a simple binary undirected graph, which adjacency matrix is $A = \{a_{i,j}\} \in \{0, 1\}^{N \times N}.$

Suppose that all vertices of such graph have at least one neighbors, i.e.

$$k_i = \sum_{j=1}^N{a_{i,j}} \geq 1.$$

How do we call this graph?

Reading the definition of connectivity, I did not find anything about this particular case.

I would say that it is "minimally connected".

Is there a proper nomenclature for these graphs?

  • $\begingroup$ What is a "binary" graph? $\endgroup$ Dec 8, 2018 at 3:41
  • 1
    $\begingroup$ Binary stands for "non-weighted", i.e. the entries of $A$ are in the set $\{0, 1\}$, not in $\mathbb{R}^+$. $\endgroup$ Dec 8, 2018 at 11:42

1 Answer 1


Requiring that every vertex have positive degree is not sufficient to make the graph connected. You may describe your graph as having no isolated vertices.

  • $\begingroup$ this makes sense. thanks a lot. $\endgroup$ Dec 8, 2018 at 11:42

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