Editing Probability distribution (section)

===One-point distribution===
A special case is the discrete distribution of a random variable that can take on only one fixed value, in other words, a Dirac measure. Expressed formally, the random variable <math>X</math> has a one-point distribution if it has a possible outcome <math>x</math> such that <math>P(X{=}x)=1.</math><ref>{{cite book |title=Probability Theory and Mathematical Statistics |first=Marek |last=Fisz |edition=3rd |publisher=John Wiley & Sons |year=1963 |isbn=0-471-26250-1 |page=129}}</ref> All other possible outcomes then have probability 0. Its cumulative distribution function jumps immediately from 0 before <math>x</math> to 1 at <math>x</math>. It is closely related to a deterministic distribution, which cannot take on any other value, while a one-point distribution can take other values, though only with probability 0. For most practical purposes the two notions are equivalent.