Ikkyū (一休宗純, Ikkyū Sōjun, 1394–1481) was an eccentric, iconoclastic Japanese Zen Buddhist monk and poet. He had a great impact on the infusion of Japanese art and literature with Zen attitudes and ideals. == Biography == === Childhood === Ikkyū was born in 1394 in a small suburb of Kyoto. It is generally held that he was the son of Emperor Go-Komatsu and a low-ranking court noblewoman. His mother was forced to flee to Saga (嵯峨), where Ikkyū was raised by servants. At the age of five, Ikkyū was separated from his mother and placed in a Rinzai Zen temple in Kyoto called Ankoku-ji, as an a...

In theoretical physics, the renormalization group (RG) refers to a mathematical apparatus that allows systematic investigation of the changes of a physical system as viewed at different distance scales. In particle physics, it reflects the changes in the underlying force laws (codified in a quantum field theory) as the energy scale at which physical processes occur varies, energy/momentum and resolution distance scales being effectively conjugate under the uncertainty principle (cf. Compton wavelength). A change in scale is called a scale transformation. The renormalization group is intimately...

In mathematics, a tubular neighborhood of a submanifold of a smooth manifold is an open set around it resembling the normal bundle. The idea behind a tubular neighborhood can be explained in a simple example. Consider a smooth curve in the plane without self-intersections. On each point on the curve draw a line perpendicular to the curve. Unless the curve is straight, these lines will intersect among themselves in a rather complicated fashion. However, if one looks only in a narrow band around the curve, the portions of the lines in that band will not intersect, and will cover the entire band without...