Noetherian rings have primary decompositions, and simplify the First Uniqueness Theorem concerning the uniqueness of associated prime ideals. Call an ideal I of a ring A irreducible if, for all ideals J , K of A , I = J ∩K =⇒ I = J or I = K. Lemma: Every ideal of a Noetherian ring is a finite intersection of irreducible ideals. 808