Definition:Graph (Graph Theory)/Size

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Let $G = \struct {V, E}$ be a graph.

The size of $G$ is the count of its edges.

That is, the size of a graph $G = \struct {V, E}$ is $\card E$.


Arbitrary Order $4$ Graph

Let $G = \struct {V, E}$ be the graph defined as:

$V = \set {v_1, v_2, v_3, v_4}$.
$E = \set {\set {\tuple {v_1, v_2}, \tuple {v_2, v_1} }, \set {\tuple {v_1, v_3}, \tuple {v_3, v_1} }, \set {\tuple {v_2, v_3}, \tuple {v_3, v_2} }, \set {\tuple {v_3, v_4}, \tuple {v_4, v_3} } }$

Then the size of $G$ is the cardinality of $E$:

$\card E = 4$

Also see

A size zero graph is called an edgeless graph.