ambiguity. When a statement such as "Some politicians are not corrupt" is said to distribute the "corrupt people" group to "some politicians", the information seems of little value, since the group "some politicians" is not defined; This is the de dicto interpretation of the intensional statement (), or "Some politicians (or other) are not corrupt". But if, as an example, this group of "some politicians" were defined to contain a single person, Albert, the relationship becomes clearer; This is the de re interpretation of the intensional statement (), or "Some politicians (in particular) are not corrupt". The statement would then mean that, of every entry listed in the corrupt people group, not one of them will be Albert: "All corrupt people are not Albert". This is a definition that applies to every member of the "corrupt people" group, and is, therefore, distributed. Summary In short, for the subject to be distributed, the statement must be universal (e.g., "all", "no"). For the predicate to be distributed, the statement must be negative (e.g., "no", "not"). Criticism Peter Geach and others have criticized the use of distribution to determine the validity of an argument. It has been suggested that statements of the form "Some A are not B" would be less problematic if stated as "Not every A is B," which is perhaps a closer translation to Aristotle's original form for this type of statement. Operations on categorical statements There are several operations (e.g., conversion, obversion, and contraposition) that can be performed on a categorical statement to change it into another. The new statement may or may not be equivalent to the original. [In the following tables that illustrate such operations, at each row, boxes are green if statements in one green box are equivalent to statements in another green box, boxes are red if statements in one red box are inequivalent to statements in another red box. Statements in a yellow box means that these are implied or valid by the statement in the left-most box when the condition stated in the same yellow box is satisfied.] Some operations require the notion of the class complement. This refers to every element under consideration which is not an element of the class. Class complements are very similar to set complements. The class complement of a set P will be called "non-P". Conversion The simplest operation is conversion where the subject and predicate terms