import algebra.group algebra.precategory.basic open eq sigma unit category path_algebra section parameters {P₀ : Type} [P : precategory P₀] structure my_structure := (a : P₀) (b : P₀) (f : @hom P₀ P a b) include P structure another_structure (X : my_structure) := (field1 : hom (my_structure.a X) (my_structure.a X)) end