The Invariant Two-Parameter Function of Algebras ψ Escobar, José María Núñez-Valdés, Juan Pérez Fernández, Pedro Invariant functions Contractions of algebras Lie algebras Malcev algebras Heisenberg algebras At present, the research on invariant functions for algebras is very extended since Hrivnák and Novotný defined in 2007 the invariant functions y and j as a tool to study the Inönü–Wigner contractions (IW-contractions), previously introduced by those authors in 1953. In this paper, we introduce a new invariant two-parameter function of algebras, which we call ¯y, as a tool which makes easier the computations and allows researchers to deal with contractions of algebras. Our study of this new function is mainly focused in Malcev algebras of the type Lie, although it can also be used with any other types of algebras. The main goal of the paper is to prove, by means of this function, that the five-dimensional classical-mechanical model built upon certain types of five-dimensional Lie algebras cannot be obtained as a limit process of a quantum-mechanical model based on a fifth Heisenberg algebra. As an example of other applications of the new function obtained, its computation in the case of the Lie algebra induced by the Lorentz group SO(3, 1) is shown and some open physical problems related to contractions are also formulated. 2020-01-20T08:34:35Z 2020-01-20T08:34:35Z 2019-10-14 info:eu-repo/semantics/article Escobar, J. M., Núñez-Valdés, J., & Pérez-Fernández, P. (2019). The Invariant Two-Parameter Function of Algebras ψ. Mathematical and Computational Applications, 24(4), 89. http://hdl.handle.net/10481/58913 10.3390/mca24040089 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España MDPI