ASSUMPTIONS _ _ _ _ _ _ _ _ _ _ _ _ variable

After solving a linear or polynomial equation system with parameters, the variable assumptions contains a list of side relations for the parameters. The solution is valid only as long as none of these expression is zero.

examples:

solve({a*x-b*y+x,y-c},{x,y});

       b*c
  {{x=-----,y=c}} 
      a + 1


assumptions; 

  {a + 1}