That's a proper function, a conformal mapping, etc.
A relation is a mapping or pairing of input values with output values.
Relation
cost or input
A relation has pairs of numbers. A function is a special relation where for each input there is one and only one output.
This is true. If a given input value yields four output values that relationship can be best described as a relation.
It's a type of function
No, not every relation is a function. In order for a relation to be a function, each input value must map to exactly one output value. If any input value maps to multiple output values, the relation is not a function.
It is a bijective function.
Is called "function".
A one-to-one or injective function.
function
A relation is a mapping or pairing of input values with output values.
A relation is a function if every input has a distinct output.
Productivity
Relation
A one-to-one function, a.k.a. an injective function.
This is true. Furthermore, functions can be broken down into one-to-one (each input provides a different output), and onto (all of Y is used when f(x) = y).