A network is an example of a directed one, and one of these is undirected if it lacks arrows on the edges connecting its nodes.
One type of these entities cannot contain K-sub-3,3 or K-sub-5 as a minor according to Kuratowski's theorem, and the spectrum of one of these is the set of eigenvalues of its adjacency matrix. Barnette's conjecture concerns the existence of a Hamiltonian cycle for one of these, and "pseudo" ones allow the presence of loops. A network is an example of a directed one, and one of these is undirected if it lacks arrows on the edges connecting its nodes. For 10 points, name these mathematical constructs which share a name with statistical diagrams coming in "line" and "bar" varieties.
One type of these entities cannot contain K-sub-3,3 or K-sub-5 as a minor according to Kuratowski's theorem, and the spectrum of one of these is the set of eigenvalues of its adjacency matrix.
Graphs