expressive power of modern logic systems like the first-order predicate calculus, they still retain practical value in addition to their historic and pedagogical significance. Translating statements into standard form Sentences in natural language may be translated into standard forms. In each row of the following chart, S corresponds to the subject of the example sentence, and P corresponds to the predicate. Note that "All S is not P" (e.g., "All cats do not have eight legs") is not classified as an example of the standard forms. This is because the translation to natural language is ambiguous. In common speech, the sentence "All cats do not have eight legs" could be used informally to indicate either (1) "At least some, and perhaps all, cats do not have eight legs" or (2) "No cats have eight legs". Properties of categorical propositions Categorical propositions can be categorized into four types on the basis of their "quality" and "quantity", or their "distribution of terms". These four types have long been named A, E, I, and O. This is based on the Latin (I affirm), referring to the affirmative propositions A and I, and (I deny), referring to the negative propositions E and O. Quantity and quality Quantity refers to the number of members of the subject class (A class is a collection or group of things designated by a term that is either subject or predicate in a categorical proposition.) that are used in the proposition. If the proposition refers to all members of the subject class, it is universal. If the proposition does not employ all members of the subject class, it is particular. For instance, an I-proposition ("Some S is P") is particular since it only refers to some of the members of the subject class. Quality It is described as whether the proposition affirms or denies the inclusion of a subject within the class of the predicate. The two possible qualities are called affirmative and negative. For instance, an A-proposition ("All S is P") is affirmative since it states that the subject is contained within the predicate. On the other hand, an O-proposition ("Some S is not P") is negative since it excludes the subject from the predicate. An important consideration is the definition of the word some. In logic, some refers to "one or more", which is consistent with "all". Therefore, the statement "Some S is P" does not guarantee