#
# Polynomials are represented in dense representation, as a list of
# coefficients, starting with the coefficient in degree zero. Lists
# are comma-separated and enclosed in parentheses. Polynomials may
# be preceded by a modifier of the form (d,m); this means that X^d
# has to be substituted in the polynomial, and that the result should
# be multiplied by X^m; in particular, this is how Laurent polynomials
# are obtained. An absent modifier is equivalent to the modifier (1,0).
