In graph theory, a biconnected component is a maximal biconnected subgraph. Any connected graph decomposes into a tree of biconnected components called the block-cut tree of the graph. The blocks are attached to each other at shared vertices called cut vertices or articulation points. Articulation points, Bridges,. Biconnected Components. • Let G = (V;E) be a connected, undirected graph. • An articulation point of G is a vertex whose removal. Thus, a graph without articulation points is biconnected. The following figure illustrates the articulation points and biconnected components of a small graph.

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Views Read Edit View history. Articles with example pseudocode. A biconnected component of a graph is a connected subgraph that cannot be broken into disconnected pieces by deleting any single node and its incident links. The lowpoint of v can be computed after visiting all descendants of v i. An articulation point is a node of a graph whose removal would cause an increase in the number of connected compoments.

Biconnected component – Wikipedia

The root vertex must be handled separately: The structure of the blocks and cutpoints of a connected graph can be described by a tree called the block-cut tree or BC-tree. Let C be a chain biconnedted of G. Guojing Cong and David A. Less obviously, this is a transitive relation: This algorithm works only anc undirected graphs.

The blocks are attached to each other at shared vertices called cut vertices or articulation points. In the online version of the problem, vertices and edges are added but not removed dynamically, and a data structure must maintain the biconnected components.


For each link in the links data set, the variable biconcomp identifies its component. By using this site, you agree to the Terms of Use and Privacy Policy.

Any connected graph decomposes into a tree of biconnected components called the block-cut tree of the graph. Note that the terms child and parent denote the relations in the DFS tree, not the original graph. Thus, the biconnected components partition the edges of the graph; however, they may share vertices with each other.

The following statements calculate the biconnected components and articulation points and output the results in the data sets LinkSetOut and NodeSetOut:. In this articulatuon, articulation points are critical to communication. Thus, it has one vertex for each block of Gand an edge between two vertices whenever the corresponding two blocks share a vertex. This tree has a vertex for each block and for each articulation point of the given graph.

Specifically, a cut vertex is any vertex whose removal increases the number of connected components.

Therefore, this is an equivalence relationand it can be used to partition the edges into equivalence classes, subsets of edges with the property that two edges are related to each other if and only if they belong to the same equivalence class. The subgraphs formed by the edges in each equivalence class are the biconnected components of the given graph.

Speedups exceeding 30 based on the original Tarjan-Vishkin algorithm were reported by James A.

Examples of where articulation points are important are airline hubs, electric circuits, network wires, protein bonds, traffic routers, and numerous other industrial applications.

The component identifiers are numbered sequentially starting from 1.

Biconnected Components

A simple alternative to the above algorithm uses chain decompositionswhich are special ear decompositions depending on DFS -trees. For each node in the nodes data set, the variable artpoint is either 1 if the node is an articulation point or 0 otherwise.


Communications of the ACM. Bader [5] developed an algorithm that achieves a speedup of 5 with 12 processors on SMPs. Articulation points can be important when you analyze any graph that represents a communications network. Every edge is related to itself, and an edge e is related to articulaion edge f if and only if f is related in the same way to e.

The depth is standard to maintain during a depth-first search. This can be represented by computing one biconnected component out of every bionnected y a component which contains y will contain the subtree of yplus vand then erasing the subtree of y from the tree.

Edwards and Uzi Vishkin Jeffery Westbrook and Robert Tarjan [3] developed an efficient data structure for this problem based on disjoint-set data structures. A vertex v in a connected graph G with minimum degree 2 is a cut vertex if and only if ppints is incident to a bridge or v is the first vertex of a cycle in C – C articulxtion. The block graph of a given graph G is the intersection graph of its blocks.

This page was last edited on 26 Novemberat The list of cut vertices can be used to create the block-cut tree of G in linear time.

A Simple Undirected Graph G.