  A bounded automorphism of a field or a group with trivial approximate centre
is definable. In an expansion of a field by a Pfaffian family F of additive
endomorphisms such that algebraic closure in the expansion coincides with
relative field-algebraic closure of the F-substructure generated, a bounded
endomorphism, possibly composed with a power of the Frobenius, is a composition
of endomorphisms associated with F.
