Stopping timeIn probability theory, in particular in the study of stochastic processes, a stopping time (also Markov time, Markov moment, optional stopping time or optional time) is a specific type of “random time”: a random variable whose value is interpreted as the time at which a given stochastic process exhibits a certain behavior of interest. A stopping time is often defined by a stopping rule, a mechanism for deciding whether to continue or stop a process on the basis of the present position and past events, and which will almost always lead to a decision to stop at some finite time.
Wave equationThe (two-way) wave equation is a second-order linear partial differential equation for the description of waves or standing wave fields - as they occur in classical physics - such as mechanical waves (e.g. water waves, sound waves and seismic waves) or electromagnetic waves (including light waves). It arises in fields like acoustics, electromagnetism, and fluid dynamics. Single mechanical or electromagnetic waves propagating in a pre-defined direction can also be described with the first-order one-way wave equation, which is much easier to solve and also valid for inhomogeneous media.
Ode on a Grecian Urn"Ode on a Grecian Urn" is a poem written by the English Romantic poet John Keats in May 1819, first published anonymously in Annals of the Fine Arts for 1819 (see 1820 in poetry). The poem is one of the "Great Odes of 1819", which also include "Ode on Indolence", "Ode on Melancholy", "Ode to a Nightingale", and "Ode to Psyche". Keats found existing forms in poetry unsatisfactory for his purpose, and in this collection he presented a new development of the ode form.
