A second type of modeling uses the first core aspect in generalizing and expressing patterns and regularities in situations or phenomena arising either outside mathematics or from within mathematics ( e.g. geometric patterns.) Here the domain of generalization is the situation being modeled and often the expression of the generalization takes the from of using one or more variables that may then express a function or class of functions. Of course working with such expressions to gain insight into the situation being modeled usually involves the syntactic aspect of algebra.