arXiv subjects

E. T. Schmidt

Publications and source records attributed to E. T. Schmidt.

4 recordsLinked to original sources

arXiv2013

Isoform lattices

Let $L$ be a lattice. We call a congruence relation $\gQ$ of $L$ isoform, if any two congruence classes of $\gQ$ are isomorphic (as lattices). Let us call the lattice $L$ isoform, if all congruences of $L$ are isoform. G. Grätzer and E.\,T. Schmidt proved that every finite distributive lattice $D$ can be represented as the congruence lattice of a finite isoform lattice $L$. We now prove that every finite lattice $K$ has a congruence-preserving extension to a finite isoform lattice $L$.

math.RA↗

arXiv2013

An extension theorem for planar semimodular lattices

We prove that every finite distributive lattice $D$ can be represented as the congruence lattice of a rectangular lattice $K$ in which all congruences are principal. We verify this result in a stronger form as an extension theorem.

math.RA↗

arXiv2013

The order of principal congruences of a semimodular lattice

This paper has been withdrawn by the authors due to a crucial computational error. In this paper we deal with the finite case. We prove that a finite bounded ordered set can be represented as the order of principal congruences of a finite \emph{semimodular lattice}.

math.RA↗

arXiv2013

A short proof of the congruence representation theorem for semimodular lattices

In a 1998 paper with H. Lakser, the authors proved that every finite distributive lattice $D$ can be represented as the congruence lattice of a finite \emph{semimodular lattice}. Some ten years later, the first author and E. Knapp proved a much stronger result, proving the representation theorem for \emph{rectangular lattices}. In this note we present a short proof of these results.

math.RA↗