In
mathematics, especially in applications of
linear algebra to
physics, the
Einstein notation or
Einstein summation convention is a notational convention that implies summation over a set of indexed terms in a formula, thus achieving notational brevity. As part of mathematics it is a notational subset of
Ricci calculus; however, it is often used in applications in physics that do not distinguish between
tangent and
cotangent spaces. It was introduced to physics by
Albert Einstein in 1916.