Adjacency list

context

$V$ … countable set

definiendum

$\phi\in\mathrm{it}$

postulate

$\mathrm{dom}\ \phi = V$

for all

$v,u\in V$

postulate	$\phi(v)\subseteq V$
postulate	$u\in\phi(v)\implies v\in\phi(u)$

The value $\phi(v)$ denotes the set of vertices which are connected to $v$ .

The adjacency lists describe simple graph.