## Incidence matrix

### Set

context | $n_v,m_e\in \mathbb N$ |

definiendum | $ M\in \mathrm{it}(n_v,m_e) $ |

postulate | $ \mathrm{Matrix}(n_v,m_e,\{0,1,2\}) $ |

for all | $i\in\mathrm{range}(n_v)$ |

postulate | $\sum_{j=1}^{m_e} M_{ij}=2 $ |

### Discussion

The index $i$ in $M_{ij}$ labels the vertices and the index $j$ labels the edges. The definition says that every edge has exactly two endpoints.

Every incidence matrix corresponds to (a representative of the isomorphism class of) a finite undirected graph.

### Parents

#### Subset of