A relational language with deductions, functions and recursions

摘要

We propose here a .relational algebra capable of deducing tuples from a premise expressed in an extended relational form: it also supports user-defined and recursive functions in the form of parameterised views, and provides a facility for easier specification of queries. The paper shows the power of the language in dealing with problems such as ancestors, part explosions and connected tours.This language, called DEAL, is an enhanced version of the PRECI Algebraic Language (PAL) but presented here in a SQL-like syntax.