Varieties of modular ortholattices
The lattice L of varieties of modular ortholattices contains the countable chain, MOn \((n<\omega)\), of varieties generated by Chinese lanterns over n elements. Denote by MO\(\omega\) a least upper bound of MOn's in L. The author proves that every variety in L distinct from all MOn's contains MO\(\omega\). The method he uses is essentially ring theoretic and seems to admit further application in the realm of ortholattices. (It should be noted that the result brings a partial answer to a conjecture of \textit{G. Bruns} [Houston J. Math. 9, 1-7 (1983; Zbl 0518.06007)].)
scientific article; zbMATH DE number 4002146