RT Journal Article T1 On isomorphism conditions for algebra functors with applications to Leavitt Path Algebras A1 Gil-Canto, Cristóbal A1 Martín-Barquero, Dolores A1 Martín-González, Cándido A1 Ruiz Campos, Iván K1 Grafos, Teoría de K1 Álgebra AB We introduce certain functors from the category of commu-tative rings (and related categories) to that of Z-algebras (not neces-sarily associative or commutative). One of the motivating examples isthe Leavitt path algebra functor R → L R (E) for a given graph E. Ourgoal is to find “descending” isomorphism results of the type: if F , Gare algebra functors and K ⊂ K a field extension, under what condi-tions an isomorphism F (K ) ∼= G (K ) of K -algebras implies the exis-tence of an isomorphism F (K) ∼= G (K) of K-algebras? We find somepositive answers to that problem for the so-called “extension invari-ant functors” which include the functors associated with Leavitt pathalgebras, Steinberg algebras, path algebras, group algebras, evolutionalgebras and others. For our purposes, we employ an extension of theHilbert’s Nullstellensatz Theorem for polynomials in possibly infinitelymany variables, as one of our main tools. We also remark that for exten-sion invariant functors F , G , an isomorphism F (H) ∼= G (H), for someK-algebra H endowed with an augmentation, implies the existence of anisomorphism F (S) ∼= G (S) for any commutative and unital K-algebraS. PB Springer YR 2023 FD 2023-07 LK https://hdl.handle.net/10630/29865 UL https://hdl.handle.net/10630/29865 LA eng NO Mediterr. J. Math. (2023) 20:273 https://doi.org/10.1007/s00009-023-02475-2 1660-5446/23/050001-19 DS RIUMA. Repositorio Institucional de la Universidad de Málaga RD 21 ene 2026