In graph-theoretic mathematics, a cycle double cover is a collection of cycles in an undirected graph that together include each edge of the graph exactly twice. For instance, for any polyhedral graph, the faces of a convex polyhedron that represents the graph provide a double cover of the graph: each edge belongs to exactly two faces.
It is an unsolved problem, posed by George Szekeres and Paul Seymour and known as the cycle double cover conjecture, whether every bridgeless graph has a cycle double cover. The conjecture can equivalently be formulated in terms of graph embeddings, and in that context is also known as the circular embedding conjecture.
Read more about Cycle Double Cover: Formulation, Reduction To Snarks, Reducible Configurations, Circular Embedding Conjecture, Stronger Conjectures and Related Problems
Famous quotes containing the words cycle, double and/or cover:
“The cycle of the machine is now coming to an end. Man has learned much in the hard discipline and the shrewd, unflinching grasp of practical possibilities that the machine has provided in the last three centuries: but we can no more continue to live in the world of the machine than we could live successfully on the barren surface of the moon.”
—Lewis Mumford (1895–1990)
“O, my offense is rank, it smells to heaven;
It hath the primal eldest curse upon ‘t,
A brother’s murder. Pray can I not,
Though inclination be as sharp as will;
My stronger guilt defeats my strong intent,
And like a man to double business bound
I stand in pause where I shall first begin,
And both neglect. What if this cursed hand
Were thicker than itself with brother’s blood,
Is there not rain enough in the sweet heavens
To wash it white as snow?”
—William Shakespeare (1564–1616)
“He is a stranger to me but he is a most remarkable man—and I am the other one. Between us, we cover all knowledge; he knows all that can be known and I know the rest”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)