ABSTRACT
This chapter considers the way Maple represents composite data, of which sets and lists are simple examples. It analyzes in detail the sum, product, and exponent data types, which are used to represent algebraic expressions. The chapter discusses technical than mathematical, but it is necessary for the arithmetic of polynomials and rational functions, and for understanding the behaviour of certain functions acting on expressions, such as map, seq, and select. The standard library function subs substitutes expressions with other expressions. The expression to be changed must appear as an operand of the original expression or of one of its sub-expressions. Several standard library functions make implicit use of the operand function op, by acting in various ways on the operands of an expression. The function select returns an expression of the same data type as expr, containing only the selected operands.
