@article {FranceJackson2005,
 author="Halina France-Jackson",
 title={On coatoms of the lattice of matric-extensible radicals},
 journal="Bull. Austral. Math. Soc.",
 fjournal={Bulletin of the Australian Mathematical Society},
 volume="72",
 year="2005",
 number="3",
 pages="403--406",
 issn="0004-9727",
 coden="ALNBAB",
 language="English",
 date="4th July, 2005",
 classmath="16N80",
 publisher={AMPAI, Australian Mathematical Society},
 url="http://www.austms.org.au/Publ/Bulletin/V72P3/723-5200-FranceJackson/index.shtml",
 acknowledgement={},
 abstract={ A radical $\alpha $ in the universal class of all associative rings is called matric-extensible if for all natural numbers $n$ and all rings $A$, $A\in \alpha $ if and only if $M_{n}( A) \in \alpha $, where \ $M_{n}( A) $ denotes the $n\times n$ matrix ring with entries from $A$. We show that there are no coatoms, that is, maximal elements in the lattice of all matric-extensible radicals of associative rings. }
}