Necessity of surjectivity in commutator-ideal splitting for Jordan homomorphisms
Ascertain whether the surjectivity assumption in the following statement is necessary: if A is a unital associative algebra with commutator ideal K(A)=A, then for every Jordan homomorphism φ: A → B there exists a central idempotent e in B such that x ↦ eφ(x) is a homomorphism and x ↦ (1−e)φ(x) is an antihomomorphism.
References
Since B is an arbitrary algebra, the condition that φ is surjective only means that its image is an associative algebra. We do not know whether this assumption is necessary.
— Jordan homomorphisms: A survey
(2510.16876 - Brešar et al., 19 Oct 2025) in Section 8 (Jordan homomorphisms on commutator ideals), after Theorem 8 (Theorem mt1)