AZ-Identities and Strict 2-Part Sperner Properties of Product Posets

One of central issues in extremal set theory is Sperner's theorem and its generalizations. Among such generalizations is the best-known BLYM inequality and the Ahlswede--Zhang (AZ) identity which surprisingly generalizes the BLYM into an identity. Sperner's theorem and the BLYM inequality has been also generalized to a wide class of posets. Another direction in this research was the study of more part Sperner systems. In this paper we derive AZ type identities for regular posets. We also characterize all maximum 2-part Sperner systems for a wide class of product posets. Powered by Editorial Manager® and Preprint Manager® from Aries Systems Corporation AZ-identities and Strict 2-part Sperner Properties of