Abstract

this article that regularity should be exploited while reasoning about specifications based on regular data structures (see also [20]). That does not seem to be possible if regular data structures are modeled using subsorts, perhaps because of incompatibility between regularity and subsorts. Instead of being a benefit, regularity becomes a burden. This situation is somewhat similar to an experience one would have in expressing a specification involving many data types in an unsorted (single-sorted) notation. Different types would have to be characterized by different unary predicates, and conditions expressed using these unary predicates would have to be carried around wherever terms of particular data types are used. A multisorted notation and logic are instead preferred.

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