Universal Polynomials of Several Variables for Classes of Linear Functions
A. A. Voronenko · Moscow University Computational Mathematics and Cybernetics · 2023
It was shown earlier that product $$xy$$ for $$k=6l\pm 1$$ is a universalfunction in the class of linear functions of two variables, and there exist no universal polynomials for even $$k$$ in classes of linear functions of two variables. This work proves that polynomial $$xy+xz+yz$$ is universal for classes of linear functions of three variables for arbitrary odd $$k$$ and polynomial $$xy+zw$$ is universal for classes of linear functions of four variables for arbitrary $$k$$ .