ON THE STRUCTURE OF FAMILIES OF IMMUNE, HYPERIMMUNE AND HYPERHYPERIMMUNE SETS
An. A. Mal'tsev · Mathematics of the USSR-Sbornik · 1985
The author studies the algebraic structures formed by m -degrees containing immune, hyperimmune and hyperhyperimmune sets. He shows that the family of all immune sets relative to m -reducibility forms a c -universal upper semilattice, the families of all hyperimmune and hyperhyperimmune sets do not form subsemilattices of the semilattice of all m -degrees, etc. Bibliography: 9 titles.