Bouquet graph
In mathematics, a bouquet graph, for an integer parameter, is an undirected graph with one vertex and edges, all of which are self-loops. It is the graph-theoretic analogue of the topological bouquet, a space of circles joined at a point. When the context of graph theory is clear, it can be called more simply a bouquet.
representation of an embedding of onto the projective plane.
Although bouquets have a very simple structure as graphs, they are of some importance in topological graph theory because their graph embeddings can still be non-trivial. In particular, every cellularly embedded graph can be reduced to an embedded bouquet by a partial duality applied to the edges of any spanning tree of the graph, or alternatively by contracting the edges of any spanning tree.
In graph-theoretic approaches to group theory, every Cayley–Serre graph can be represented as the covering graph of a bouquet.
