General; Incidence and adjacency, valency; Subgraphs, supergraphs; Connectivity; Paths; Trees, forests; Circuits, cycles; Acyclic digraphs; Euler paths and circuits, cycles; Hamilton paths, circuits; Vertex-coverings by small sets of paths; Spanning subgraphs, vertex-coverings; Edge-coverings; Disjoint vertex-packings; Disjoint decompositions of the edge-set, disjoint edge-packings; Internally and externally stable sets of vertices