  Kronecker's Theorem and Rabin's Theorem are fundamental results about
computable fields F and the decidability of the set of irreducible polynomials
over F. We adapt these theorems to the setting of differential fields K, with
constrained pairs of differential polynomials over K assuming the role of the
irreducible polynomials. We prove that two of the three basic aspects of
Kronecker's Theorem remain true here, and that the reducibility in one
direction (but not the other) from Rabin's Theorem also continues to hold.
