:: deftheorem defines is_naturally_transformable_to NATTRA_1:def 7 :
for A, B being Category
for F1, F2 being Functor of A,B holds
( F1 is_naturally_transformable_to F2 iff ( F1 is_transformable_to F2 & ex t being transformation of F1,F2 st
for a, b being Object of A st Hom (a,b) <> {} holds
for f being Morphism of a,b holds (t . b) * (F1 /. f) = (F2 /. f) * (t . a) ) );