Classification
In classification problems, the label space ⚠ $\mathbf{Y}$
is finite. In binary classification problems, its size is 2; usually, ⚠ $\mathbf{Y}=\{0,1\}$
or ⚠ $\mathbf{Y}=\{-1,1\}$
. Allowed forecasts in such problems are elements of ⚠ $\mathbf{Y}$
(we will have a probabilistic classification problem if we allow probability measures on ⚠ $\mathbf{Y}$
as forecasts).