If the x and y values in each pair of a set of ordered pairs are interchanged the resulting set of ordered pairs is known as the

inverse of a function
one to one function
inverse of a relation
onto function

will give !

Inverse of a relation

Reasoning:

the inverse of a function is a full function, this is just a set of pairs.  A set of pairs, or relation, where x and y values interchange are inverse of the relation.  A one to one function is when a function's inverse is also a function (doesn't have more than one y for each x) which can be tested for on the normal function's graph with a HORIZONTAL line test.  A normal parabola isn't one to one.  An onto function has to do with every value being used (I don't remember much about them, but once again this isn't a function, but rather a specific set of pairs/data)

Example of inverse of a relation:

Relation: {(0,5), (3,2)}

Inverse: {(5,0), (2,3)}

Example of inverse of a function:

f(x)=5x

f-1(x)=x/5

Example of a one to one function:

f(x)=x+1