efficient way to get a sufficient set of identifying attributes

[Robin Becker]

Given a list of objects with attributes a0, a1, a2,....an-1 is there an 
efficient way to find sets of attributes which can be used to distinguish 
members of the list?

As example a list of people might have

firstName, lastName, nationality, postcode, phonenumber,....

as attributes. The probe items may have some of these attributes, but which 
should be used to test. Presumably the information in any attribute is highest 
if the number of distinct occurrences is the the same as the list length and 
pairs of attributes are more likely to be unique, but is there some proper way 
to go about determining what tests to use?

A particular problem might be dynamic in that the list may be being constructed 
from the probes.
-- 
Robin Becker