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Rooted trees, often with an additional structure such as an ordering of the neighbors at each vertex, are a key data structure in computer science; see tree data structure. In a context where trees typically have a root, a tree without any designated root is called a free tree. A labeled tree is a tree in which each vertex is given a unique label.
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children (depending on the type of tree), but must be connected to exactly one parent, [ 1 ] [ 2 ] except for the root node, which has no parent (i.e., the ...
A tree structure, tree diagram, or tree model is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree , although the chart is generally upside down compared to a biological tree, with the "stem" at the top and the "leaves" at the bottom.
Trees with a single root may be viewed as rooted trees in the sense of graph theory in one of two ways: either as a tree (graph theory) or as a trivially perfect graph. In the first case, the graph is the undirected Hasse diagram of the partially ordered set, and in the second case, the graph is simply the underlying (undirected) graph of the ...
In graph theory and theoretical computer science, the level ancestor problem is the problem of preprocessing a given rooted tree T into a data structure that can determine the ancestor of a given node at a given distance from the root of the tree. More precisely, let T be a rooted tree with n nodes, and let v be an arbitrary node of T.
In graph theory, an arborescence is a directed graph where there exists a vertex r (called the root) such that, for any other vertex v, there is exactly one directed walk from r to v (noting that the root r is unique). [1] An arborescence is thus the directed-graph form of a rooted tree, understood here as an undirected graph.
If Φ is a root system in E, the coroot α ∨ of a root α is defined by = (,). The set of coroots also forms a root system Φ ∨ in E, called the dual root system (or sometimes inverse root system). By definition, α ∨ ∨ = α, so that Φ is the dual root system of Φ ∨.
2. A k-tree is a graph formed by gluing (k + 1)-cliques together on shared k-cliques. A tree in the ordinary sense is a 1-tree according to this definition. tree decomposition A tree decomposition of a graph G is a tree whose nodes are labeled with sets of vertices of G; these sets are called bags.