The RandomNumberLink is a type of FunctionLink that, when executed, generates a uniformly distributed random number. For example, the following:
(cog-execute! (RandomNumber (Number 0) (Number 1)))
will return a random number between zero and one. Another example:
(cog-evaluate! (GreaterThan (Number "0.5") (RandomNumber (Number 0) (Number 1))))
will return true half the time, and false the other half.