The call type(a, polynom(d, v)) checks to see if a is a polynomial in the variables v with coefficients in the domain d. A typical calling sequence would be

which tests to see if a is a polynomial in x over the integers.

The variable(s) v can be a single indeterminate, or can be a list or set of indeterminates. In the latter case, one would be testing for a multivariate polynomial.

If v is omitted, then it is taken to be a set of all the indeterminates of type name appearing in a.  Thus the function will check that a is a polynomial in all of its variables.

The domain specification d should be a type name, such as rational or algnum (algebraic number).  If the domain specification is given as anything then no restriction is placed on the coefficients.  If d is omitted, then it defaults to type constant.