RT Journal Article T1 Commutative algebras with one-dimensional square A1 Martín-Barquero, Dolores A1 Martín-González, Cándido A1 Sánchez-Ortega, Juana K1 Álgebra conmutativa K1 Clifford, Álgebras de AB In this paper, we classify and study commutative algebras having a one-dimensional square. In finite dimension (see Theorem 3.9) besides some cases (which are all associative and nilpotent with nilpotency index 3), the algebras with zero annihilator are either of symplectic type (appearing only in characteristic 2), or evolution algebras. In infinite dimension, ruling out the associative case, we prove that our algebras are either of symplectic type or evolution algebras provided some technical conditions are satisfied (see Theorem 3.12). Our main tool is the theory of inner product spaces and quadratic forms. More precisely, if A denotes an evolution algebra with dim (A2)=1 and a a generator of A2, then A admits an inner product {·, · } such that the product of A is given by xy = {x, y}a. There are three classes to consider:(1) a ∈ Ann(A);(2) a ∉ Ann(A) and a is isotropic relative to {·, ·};(3) a ∉ Ann(A) and a is anisotropic relative to {·, ·}The isomorphism problem among these objects is investigated. For some of these algebras, we have also determined the existence of faithful associative representations in certain Clifford algebras. PB Springer Nature YR 2025 FD 2025-02-26 LK https://hdl.handle.net/10630/38073 UL https://hdl.handle.net/10630/38073 LA eng NO Martín Barquero, D., Martín González, C. & Sánchez-Ortega, J. Commutative Algebras with One-Dimensional Square. Mediterr. J. Math. 22, 48 (2025). https://doi.org/10.1007/s00009-025-02812-7 NO Funding for open access charge: Universidad de Málaga / CBUA DS RIUMA. Repositorio Institucional de la Universidad de Málaga RD 20 ene 2026