This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
 Testing Expressions Mathematica symbolic expressions can represent an immense range of types of objects. Mathematica provides a rich collection of functions to test expressions. Functions that "ask a question" have names that end in Q. They return True for an explicit true answer, and False otherwise. Equality & Inequality Equal (), Unequal () — numerical equality SameQ (), UnsameQ () — literal symbolic identity Less(<)  ▪ Greater(>)  ▪ LessEqual(<=)  ▪ GreaterEqual (>=) And(&&)  ▪ Or(||)  ▪ Not(!)  ▪ True  ▪ False  ▪ ...      NumberQ, MachineNumberQ — literal number, literal machine-precision number NumericQ — numeric quantity (consisting of numbers, numeric constants and functions)      List-Oriented Tests VectorQ, MatrixQ — vector, matrix, perhaps with elements of specified types ArrayQ — full array of any depth MemberQ — test whether a pattern occurs in a list      Expression Tests MatchQ — test whether an expression matches a pattern      TUTORIALS Relational and Logical Operators Putting Constraints on Patterns Specifying Types of Expression in Patterns MORE ABOUT Conditionals Atomic Elements of Expressions Mathematica Patterns Logic & Boolean Algebra