Let $(u^1, v^1), \dots , (u^n, v^n)$ be a
paired dataset in $\mathcal{U} \times
\mathcal{V} $.An interpolator is a
predictor $f: \mathcal{U} \to \mathcal{V} $ which
satisifes for which
\[
f(u^i) = u^i
\]
for each $i = 1 , \dots , n$.In this case we say that the predictor $f$
interpolates the dataset.