| context | $V,E$ … set |
| definiendum | $\langle V,E,\psi\rangle \in \mathrm{it}(E,V) $ |
| postulate | $\langle V,E,\psi\rangle $ … undirected graph |
| range | $ X\cap Y=\emptyset $ |
| range | $ X\cup Y=V $ |
| range | $ x\in X $ |
| range | $ y\in Y $ |
| postulate | $ \forall X,Y. \exists x,y.\ \{x,y\}\in\mathrm{im}\ \psi $ |