An ideal of a lattice L is called semiprime if for every x,y,z, whenever and , then . Semiprime filters are dually defined.
Main Theorem. Let L be a lattice and I an ideal of L. The following conditions are equivalent: (1) I is semiprime. (2) I is the kernel of some homomorphism of L onto a distributive lattice with zero. (3) I is the kernel of a homomorphism of L onto a semiprime lattice (if the zero ideal is semiprime).
The following Birkhoff-Stone prime separation theorem generalization is obtained: Corollary. The following statements are equivalent in Zermelo- Fraenkel set theory (without Choice): (a) The Ultrafilter Principle. (b) If a lattice L contains an ideal I and a filter F which are disjoint and such that either I or F is semiprime, then there exists a partition of L by a prime ideal P and a prime filter such that and
Moreover, the author proves several other results such as: Theorem 4.2. Every semiprime ideal of a lattice is representable as an intersection of prime ideals iff the Ultrafilter Principle holds. Theorem 5.2. A lattice is distributive iff, for every ideal I and filter F of L such that , there is an ideal J and a filter G of L such that , , , and either J or G is semiprime.