Bradley, J.2008-02-272008-02-271985-03-01http://hdl.handle.net/1880/46281Modes of association are defined for the recursive associations that occur in bill of materials data bases and data bases for the family tree of corporations. It is shown that a series of useful modes may be defined. Modes of association may be schema defined to enable a relational data base system capture more meaning about an association. When used with natural quantifiers and SQL/N, an upward-compatible extension of SQL, they permit construction of concise expressions for complex retrievals involving explosions and implosions of entities described in the data base. A mode of association is a set of propositions, each describing a pair of associated entities.EngComputer Scienceunknown1985-202-1510.11575/PRISM/30419