• definition and notation

    TITLE: formal logic: Set theory
    SECTION: Set theory
    ...y> and <y, x> are in general not identical). Let x and y be any classes, as (for example) those of the dots on the two arms of a stippled cross. The intersection of x and y, symbolized as xy, is the class the members of which are the objects common to x and y—in this case the dots within the...
    TITLE: set theory: Operations on sets
    SECTION: Operations on sets
    The intersection operation is denoted by the symbol ∩. The set AB—read “A intersection B” or “the intersection of A and B”—is defined as the set composed of all elements that belong to both A and B. Thus, the intersection of the two committees in the foregoing example is the set consisting of...