# 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).