Definition
Field F_2
Field F_2 with its specified scalar field, operations, and categorical structure.
For the field is the quotient field , with residue-class addition and multiplication.
Operations and maps
Every nonzero residue has an inverse because 2 is prime. A unit-preserving field endomorphism fixes , hence every sum of copies of , and is therefore the identity. The zero map is allowed as a nonunital ring map, but never as a field map.
Underlying groups
Its additive group is cyclic of order ; its nonzero elements form a separate multiplicative group of order . These group structures must be selected explicitly before taking group Hom-sets.