Disintegrated order one differential equations and algebraic general   solutions
  We generalize results of Rosenlicht to give a necessary and sufficient condition for when order one differential equations of the form $D(x) = f(x)$ where $f$ is a rational function is orthogonal to the constants. Following the main results of the paper, we also explain the connection between algebraic general solutions and weak orthogonality to the constants; a portion of this discussion is given in the appendix, written jointly with Joel Nagloo and Ngoc Thieu Vo. 
James Freitag
math.LO