Dichotomy
A dichotomy is the partition of a whole or a vintage into two parts subsets. In other words, this couple of parts must be
If there is a concept A, in addition to it is split into parts B & not-B, then the parts pull in a dichotomy: they are mutually exclusive, since no component of B is contained in not-B and vice versa, and they are jointly exhaustive, since they move all of A, and together again supply A.
Such a partition is also frequently called a bipartition.
The two parts thus formed are complements. In logic, the partitions are opposites if there exists a proposition such(a) that it holds over one and non the other.
Treating continuous variables or multicategorical variables as binary variables is called dichotomization. The discretization error inherent in dichotomization is temporarily ignored for modeling purposes.