Solving some functional and operational equations.
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Olteanu, Alina, Olteanu, Octav (2008)
APPS. Applied Sciences
Risteski, I.B., Covachev, V.C. (2006)
Acta Mathematica Universitatis Comenianae. New Series
John AQ. Baker (1994)
Aequationes mathematicae
Hermann König, Vitali Milman (2014)
Studia Mathematica
Let T: C¹(ℝ) → C(ℝ) be an operator satisfying the “chain rule inequality” T(f∘g) ≤ (Tf)∘g⋅Tg, f,g ∈ C¹(ℝ). Imposing a weak continuity and a non-degeneracy condition on T, we determine the form of all maps T satisfying this inequality together with T(-Id)(0) < 0. They have the form Tf = ⎧ , f’ ≥ 0, ⎨ ⎩ , f’ < 0, with p > 0, H ∈ C(ℝ), A ≥ 1. For A = 1, these are just the solutions of the chain rule operator equation. To prove this, we characterize the submultiplicative, measurable functions...
C. Bourlet (1897)
Annales scientifiques de l'École Normale Supérieure
C. Bourlet (1897)
Bulletin de la Société Mathématique de France
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