An information system with the ability to extract intelligence from data

In collating systelns, once one has a set of records to be displayed, one has the problem of sorting t h e m in some specified manner. If the field being sorted on appears at inost once in every record, there is no problem. Suppose, however, each record from which we have ext rac ted out' da ta has as subject a part icular apa r tmen t house in some city and suppose tha t among the data in the record are the rmmes of all the tenants and the address of tile apartment house. If the interrogation reads " I n alphabetical order, list the names and addresses of all people who live in apar tment houses in tha t ci ty", arl,ifieial l~eords are created for sorting, duplicating the address of the house for each person who lives in it. l"urther complicat ions arise if more than one level of sorting is specified a t orm time.