In mathematics, specifically in algebraic geometry, a formal scheme is a type of space which includes data about its surroundings. Unlike an ordinary scheme, a formal scheme includes infinitesimal data that, in effect, points in a direction off of the scheme. For this reason, formal schemes frequently appear in topics such as deformation theory. But the concept is also used to prove a theorem such as the theorem on formal functions, which is used to deduce theorems of interest for usual schemes.
A locally noetherian scheme is a locally noetherian formal scheme in the canonical way: the formal completion along itself. In other words, the category of locally noetherian formal schemes contains all locally noetherian schemes.
Read more about Formal Scheme: Definition, Morphisms Between Formal Schemes, See Also
Famous quotes containing the words formal and/or scheme:
“True variety is in that plenitude of real and unexpected elements, in the branch charged with blue flowers thrusting itself, against all expectations, from the springtime hedge which seems already too full, while the purely formal imitation of variety ... is but void and uniformity, that is, that which is most opposed to variety....”
—Marcel Proust (1871–1922)
“Your scheme must be the framework of the universe; all other schemes will soon be ruins.”
—Henry David Thoreau (1817–1862)