While induction in Aleph was performed with the same target language as in our approach, the target language of ALP is JAPE, which has been shown (Chiticariu et al., 2010b) to lack in some of the constructs (such as minus) that AQL provides and which form a part of our target language (especially the rule refinement phase).
the formal definition of these operators takes the form of an algebra (Reiss et al., 2008), similar to relational algebra, but with extensions for text processing.