# Closure In mathematics closure refers to the circumstance where a common space serves as both the input and output of a given operation. For example addition will always map two real numbers to another real number so we can say that the real numbers are closed under addition. Alternatively division will in general map two integers not to another integer but rather to a rational number. Consequently the integers are not closed under division. --- Date: 20220803 Links to: [Mathematics MOC](Mathematics%20MOC) Tags: #review References: * [Probabilistic Building Blocks](https://betanalpha.github.io/assets/case_studies/probability_densities.html)