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**dichotomy**is any splitting of a whole into exactly two non-overlapping parts, meaning it is a procedure in which a whole is divided into two parts. It is a__partition__of a whole (or a set) into two parts (subsets) that are:__jointly exhaustive__: everything must belong to one part or the other, and__mutually exclusive__: nothing can belong simultaneously to both parts.

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 that it holds over one and not the other.

The term comes from the __Greek__ *dichotomia* (Greek: "διχοτομία") (divided): *dich-* (form of *dícha*, in two, asunder); *tomia-* a combining form meaning cutting, incision, excision of an object

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