Let (𝔘, ɛu
) and (𝔅, ɛb
) be two pointed sets. Given a family of three maps ℱ = {f
1 : 𝔘 → 𝔘; f
2 : 𝔘 × 𝔘 → 𝔘; f
3 : 𝔘 × 𝔘 → 𝔅}, this family provides an adequate decomposition of 𝔘 \ {ɛu
} as the orthogonal disjoint union of well-described ℱ-invariant subsets. This decomposition is applied to the structure theory of graded involutive algebras, graded quadratic algebras and graded weak H
*-algebras.