Equilibrium can be broadly classified as heterogeneous and homogeneous equilibrium. Mixtures can be either homogeneous or heterogeneous. Enzymes possess properties of both homogeneous and heterogeneous catalysts. Catalysts may be classified as either homogeneous or heterogeneous. The material is assumed to be an isotropic, homogeneous, and linear elastic. This simplified definition holds for a homogeneous and isotropic system. Projective varieties were subsets defined by a set of homogeneous polynomials. Systems of homogeneous linear equations are closely tied to vector spaces. Stratification is the process of dividing members of the population into homogeneous subgroups before sampling. Finland is a relatively ethnically homogeneous country. These usually involve fields in linear homogeneous media. A simple example is a system of dilute molecules diffusing in a homogeneous environment. Information within these clusters tends to be rather homogeneous and redundant. An example of a homogeneous mixture is air. It is much more common than homogeneous nucleation.