“A given proposition is knowable a priori if it can be known independent of any experience other than the experience of learning the language in which the proposition is expressed, whereas a proposition that is knowable a posteriori is known on the basis of experience. For example, the proposition that all bachelors are unmarried is a priori, and the proposition that it is raining outside now is a posteriori.”
The UML Class Diagram above shows the a priori – a posteriori model.
The source of all citations and more about the topic in: Jason S. Baehr, “Priori and A Posteriori“, Internet Encyclopedia of Philosophy
Philosophy Models 