3ball

3ball, or 3-ball, is a term used in different fields to refer to distinct concepts, depending on context. In cue sports, 3-ball denotes a quick, three-ball pool variant played with balls numbered 1 through 3. The game is typically played on a standard pool table, with players required to strike the lowest-numbered ball first on each shot and the objective of legally pocketing all three balls. Variations in rules exist across venues and informal settings, but the format is commonly valued for its speed and simplicity.

In mathematics, the 3-ball refers to the three-dimensional ball in Euclidean space. Specifically, it is the closed unit ball B^3 = {x in R^3 : ||x|| ≤ 1}, whose boundary is the 2-sphere S^2. The 3-ball is a fundamental object in topology and geometry, used to illustrate properties of manifolds, compactness, and boundary structure. It is homeomorphic to any solid ball in three dimensions and serves as a standard reference in many proofs and constructions.

Beyond sports and mathematics, 3ball can appear as a brand name or product designation in various industries, including consumer electronics, apparel, or entertainment. In such cases, the meaning is highly context-dependent and not tied to a single universal definition.

See also: n-ball; 2-ball; topology of balls.