1.NounFor a given function f, another function, denoted f, that reverses the mapping action of f; given a function
f
:
X
→
Y
{\displaystyle f:X\rightarrow Y}
, a function
g
:
Y
→
X
{\displaystyle g:Y\rightarrow X}
such that,
∀
x
∈
X
,
f
(
x
)
=
y
⟹
g
(
y
)
=
x
{\displaystyle \forall x\in X,\ f(x)=y\implies g(y)=x}
.
"Halving is the inverse function of doubling.; If an inverse function exists for a given function, then it is unique.; The inverse function of an inverse function is the original function."