lhs === rhs yields True if the expression lhs is identical to rhs, and yields False otherwise.

Mathematica provides various ways to set up conditionals, which specify that particular expressions should be evaluated only if certain conditions hold. Conditional ...

Mathematica provides a general mechanism for specifying constraints on patterns. All you need to do is to put /;condition at the end of a pattern to signify that it applies ...

SameTest is an option whose setting gives a pairwise comparison function to determine whether expressions should be considered the same.

TrueQ[expr] yields True if expr is True, and yields False otherwise.

Order[expr_1, expr_2] gives 1 if expr_1 is before expr_2 in canonical order, and -1 if expr_1 is after expr_2 in canonical order. It gives 0 if expr_1 is identical to expr_2.

Mathematica's symbolic character allows a powerful unification of the notion of conditionals in programming and in mathematics.

StringQ[expr] gives True if expr is a string, and False otherwise.

lhs =!= rhs yields True if the expression lhs is not identical to rhs, and yields False otherwise.

At the core of Mathematica is the foundational idea that everything —data, programs, formulas, graphics, documents—can be represented as symbolic expressions. And it is this ...