  In this paper, we prove decidability properties and new results on the
position of the family of languages generated by (circular) splicing systems
within the Chomsky hierarchy. The two main results of the paper are the
following. First, we show that it is decidable, given a circular splicing
language and a regular language, whether they are equal. Second, we prove the
language generated by an alphabetic splicing system is context-free. Alphabetic
splicing systems are a generalization of simple and semi-simple splicin systems
already considered in the literature.
