In the item "mapping" it says
"A mapping or map in mathematics, synonymous with a function."
I would like to add the following:
"Two non-empty sets A and B, and the correspondence rule f, according to which any single element in the set A has a corresponding unique element in the set B, are called mapping, denoting f: A→B. Since a function is defined as a mapping from one non-empty number set to another non-empty number set, the following example is a mapping, but not a function: A = {points P on a circle O}, B = {tangents of the circle O}, the correspondence rule f: making tangents of the circle O through the points P."
I hope some one who sees this could help me submit the above paragraph for editing "Mapping" page in Wikipedia.
L.W. Zhou (7 Oct, 2006)