Graffiti it is a rapidly developing art form whose value is highly contested and reviled by many authorities while also subject to protection, sometimes within the same jurisdiction. Both "graffiti" and its occasional singular form "graffito" are from the Italian word "graffiato" ("scratched"). "Graffiti" is applied in art history to works of art produced by scratching a design into a surface. A related term is "sgraffito", which involves scratching through one layer of pigment to reveal another beneath it. This technique was primarily used by potters who would glaze their wares and then scratch a design into it. In ancient times
Singular point of a curve Singular point of a curve In geometry, a singular point on a curve is one where the curve is not given by a smooth embedding of a parameter. The precise definition of a singular point depends on the type of curve being studied. Algebraic curves in the plane may be defined as the set of points ("x", "y") satisfying an equation of the form "f"("x", "y")=0, where "f" is a polynomial function "f":R→R. If "f" is expanded as If the origin (0, 0) is on the curve then "a"=0. If "b"≠0 then the implicit function theorem guarantees there is a