Beschreibung:
<jats:title>Abstract</jats:title><jats:p>We show that there is a computable Boolean algebra <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022481200013888_inline1" /> and a computably enumerable ideal <jats:italic>I</jats:italic> of <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022481200013888_inline1" /> such that the quotient algebra <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022481200013888_inline1" />/<jats:italic>I</jats:italic> is of Cantor-Bendixson rank 1 and is not isomorphic to any computable Boolean algebra. This extends a result of L. Feiner and is deduced from Feiner's result even though Feiner's construction yields a Boolean algebra of infinite Cantor-Bendixson rank.</jats:p>