The study of Categorical Logic is the study of some simple relationships between various sets of things, and what these relationships tell us about the validity of some arguments. Every sentence that can be usefully studied using the categorical logic has one of the four distinct forms shown above. Each sentence in categorical form asserts a relationship between two sets, the subject set and the predicate set. Many sentences of everyday english can be translated into categorical form, as demonstrated below. Every student is literate.
All students are literate people.
Penguins are not mammals. No Penguins are Mammals. At least one frog is a prince. Some Frogs are Princes. Tweety is a bird.