Counting extremal lattices.
Bogdan Chornomaz · HAL (Le Centre pour la Communication Scientifique Directe) · 2015
Extremal (n,k)-free lattices were defined as lattices with n join-irreducible elements, not containing an order embedding of boolean lattice on n atoms B(n), and reaching the bound of $\sum_{i=0}^{k-1}\binom{n}{i}$ elements. In this paper we establish a simple recursive formula for the number of isomorphism classes of those lattices for custom n and k=3.