## Loopless graph

### Set

 context $V,E$ … set
 definiendum $\langle V,E,\psi\rangle \in \mathrm{it}(E,V)$
 postulate $\langle V,E,\psi\rangle$ … undirected graph
 for all $u\in V$
 postulate $\{u,u\}$ … not an edge