8Note that a variable in a monomial or polynomial is a constant, not a mathematical variable in the Maude sense. That is, in this example variables are understood as names. Of course, in Maude we can also define a variable X:X$Elt in the parameter sort to which variables belong as constants, or, more generally, variables such as P:Poly{R, X}. In this context such mathematical variables can be distinguished from variables as names by referring to them as metavariables.