Equiprobability is a property for a collection of events that each have the same probability of occurring.
[1] In statistics and probability theory it is applied in the discrete uniform distribution and the equidistribution theorem for rational numbers.
mutually exclusive events can occur, we are justified in assigning each the probability
This subjective assignment of probabilities is especially justified for situations such as rolling dice and lotteries since these experiments carry a symmetry structure, and one's state of knowledge must clearly be invariant under this symmetry.
One procedure is to assume that these prior probabilities have some symmetry which is typical of the experiment, and then assign a prior which is proportional to the Haar measure for the symmetry group: this generalization of equiprobability is known as the principle of transformation groups and leads to misuse of equiprobability as a model for incertitude.