Consider to change current implementation of comparison operator for two polynomials to new one. Polynomials are compared lexicographicaly but different ways of monomial comparison exist. The current one compares degrees first and then coefficients. It should be replaced by new one, where first the signs of coefficients are compared, then degrees are compared and then coefficients compared, so that -x^2 is less than x+10.
Implemented at branches/linopt_symbolic #316.
Not havily tested. Test should be provided and after that it is ready to merge back to trunk.