What is "uniqueness theorem"

In mathematics, a uniqueness theorem is a theorem proving that certain conditions determine a unique solution. Examples of uniqueness theorems include:

• Alexandrov's uniqueness theorem of three-dimensional polyhedra
• Black hole uniqueness theorem
• Fundamental theorem of arithmetic, the uniqueness of prime factorization.
• Holmgren's uniqueness theorem for linear partial differential equations with real analytic coefficients.
• Picard–Lindelöf theorem, the uniqueness of solutions to first-order differential equations.
• Thompson uniqueness theorem in finite group theory.
• Uniqueness theorem for Poisson's equation
• Uniqueness case in finite group theory

A theorem, also called a unicity theorem, stating the uniqueness of a mathematical object, which usually means that there is only one object fulfilling given properties, or that all objects of a given class are equivalent (i.e., they can be represented by the same model). This is often expressed by saying that the object is uniquely determined by a certain set of data. The word unique is sometimes replaced by essentially unique, whenever one wants to stress that the uniqueness is only referred to the underlying structure, whereas the form may vary in all ways that do not affect the mathematical content.