In graph theory, a loop (also called a self-loop or a "buckle") is an edge that connects a vertex to itself. A simple graph contains no loops. For an undirected graph, the degree of a vertex is equal to the number of adjacent vertices.
In graph theory, there are several different types of object called cycles; a closed walk and a simple cycle. A closed walk consists of a sequence of vertices starting and ending at the same vertex, with each two consecutive vertices in the sequence adjacent to each other in the graph.
In mathematics, and more specifically in graph theory, a directed graph (or digraph) is a graph, or set of nodes connected by edges, where the edges have a direction associated with them. In formal terms, a digraph is a pair (sometimes ) of:
In computer science, Kosaraju's algorithm (also known as the Kosaraju–Sharir algorithm) is a linear time algorithm to find the strongly connected components of a directed graph. Aho, Hopcroft and Ullman credit it to an unpublished paper from 1978 by S. Rao Kosaraju.
In graph theory, the strongly connected components of a directed graph may be found using an algorithm that uses depth-first search in combination with two stacks, one to keep track of the vertices in the current component and the second to keep track of the current search path.
In the mathematical theory of directed graphs, a graph is said to be strongly connected if every vertex is reachable from every other vertex. The strongly connected components of an arbitrary directed graph form a partition into subgraphs that are themselves strongly connected.
... some evidence suggests human females also undergo semi-annual heat cycles. Although sexual responsiveness is influenced by social and cultural factors, there is evidence that human females undergo emotional and physiological changes associated with estrus cycles and may be more likely to be irritable and/or sexually aroused during the peaks of heat cycles. Further, just as males of other species respond in differing ways to females in...
Astronomers at the University of St Andrews worked on an international study of the star Epsilon Aurigae, from the Auriga constellation. Every 27 years it becomes dimmer, a phenomenon which lasts for two years. The physicists combined light from four telescopes to get the first image of the eclipse, which is 140 times sharper than images from the Hubble telescope.
Evidence of events that happened before the Big Bang can be seen in the glow of microwave radiation that fills the Universe, scientists have asserted. Renowned cosmologist Roger Penrose said that analysis of this cosmic microwave background showed echoes of previous Big Bang-like events. The events appear as "rings" around galaxy clusters in which the variation in the background is unusually low.