A correspondence is a rule that connects the elements of a set A (input set) with the elements of a set B (output set). A correspondence between the elements of the two sets A and B can be given in various ways, such as:
With an arrow diagram. {e.x. FigA}
By graph (set of ordered pairs) {e.x. FigB}
Using type (if any) {e.x. y2 + 3x= -1}
With a price table
With verbal-descriptive wording or symbolically {e.x. a tree grows 20 cm every year, so the height of the tree is related to its age using the function h, h=age ⸱ 20 }
A function is the special case of a pairing from set A to set B, where each element of set A is paired with only one element of set B.
The set A is called the Definition Field
The set of elements of B that are paired with elements of A is called the price range of the function.