  In Combinatorial Game Theory, short game forms are defined recursively over
all the positions the two players are allowed to move to. A form is
decomposable if it can be expressed as a disjunctive sum of two forms with
smaller birthday. If there are no such summands, then the form is
indecomposable. The main contribution of this document is the characterization
of the indecomposable nimbers and the characterization of the indecomposable
numbers. More precisely, a nimber is indecomposable if and only if its size is
a power of two, and a number is indecomposable if and only if its absolute
value is less or equal than one.
