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Identifiable examples

From: Giles Hogben <giles.hogben@jrc.it>
Date: Wed, 13 Aug 2003 17:41:34 +0200
To: <public-p3p-spec@w3.org>
Message-ID: <000901c361b1$60154c20$162abf8b@cs.jrc.it>

Here is one of the examples of how completely arbitrary information may be
identifiable, which I promised in today's call:

Take the set of facts,

F1:Prozac is an anti-depressant
F2:Steve Brown uses Prozac
F3:Robin Smith uses anti-depressants
F4:Cary Wilson doesn't use anti-depressants etc.

{F2} and {F1, **given (F2-F4.)} and {F4, **given (F1-F3.)} constitute PII
wrt Steve Brown but F1 and F3 alone do not. This shows how F1 and F4, which
apparently have nothing to do with Steve Brown, can identify him given a
certain set of background knowledge (F2-4).

I'll be able to contribute more info on this next week (paper in review)

Giles


-------------------------------------
Giles Hogben
European Commission Joint Research Centre
Institute for the Protection and Security of the Citizen
Cybersecurity and New technologies for Combatting Fraud Unit
Received on Wednesday, 13 August 2003 11:41:46 EDT

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