# A solution to integrate CWA into OWA.

From: Dave Andersen <dja222@hotmail.com>
Date: Wed, 2 Mar 2011 11:36:48 +0100
Message-ID: <COL116-W34E1CF05685F707D64852D92C00@phx.gbl>

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Dear All,

Hereby I propose a SOLUTION to elegantly integrate CWA in OWA and put an END to a (I think for MANY people) very frustrating situation: a situation where one can NOT find OWL indivuals that LACK certain properties just with the simple boolean algebra term "NOT" (due to OWA) .

PROPOSAL:
A CLOSURE AXIOM on the Knowledge Base {KB} that the user wants to query (similar to exhaustive class {enumeration} or owl:allValuesFrom).

THIS IS HOW IT WORKS:
User can activate OPTION to let reasoner put a CLOSURE AXIOM on KB: {KB}.
1. The reasoner follows the normal procedure to infer statements from asserted statements.
2. The reasoner now applies a CLOSURE action on the instantiated individuals and their properties as follows:
2.1 Collect all the individuals and the properties (ONLY their NAMES, values are NOT important)*.
2.2a Create as many so called "NullProp" classes as there are property(names).
2.2b Give each NullProp class exactly 1 single statement: property exactly 0. All properties now also have as many NullProp classes.
2.3 For every individual check that for the property at least 1 statement is present.
2.4a If it does, then move to the next property and repeat procedure.
2.4b If it doesn't, then make this individual a member of the NullProp class for this property.
2.4c Move to the next property and repeat procedure.
2.5 Are all properties assigned to this individual? Then move to the next individual and repeat procedure.
3. At the end ALL individuals MUST HAVE ALL properties assigned to, either asserted, inferred or via CLOSURE action (i.e. property exactly 0).

RESULT:
1. Every query can now be carried out with simple boolean algebra to find Individuals with OR WITHOUT certain properties: e.g. DL-Query with simple Manchester Syntax (incl. "NOT").
2. NO more complicated SPARQL or (worse) PROPRIETARY queries!
3. Simple constraints checking!!

Since (a part of) set theory is already teached in K12 schools, we greatly  increases our potential (future) OWL userbase. E.g. in social networks and messages you look for SPECIFIC things like persons,interests, opportunities, files... OR the LACK thereof, and how to carry this out in a SIMPLE way.

User Axiom :-) : To make things WIDELY accepted, LOGICAL right is NOT enough, it must also be PRACTICALLY right (read: relatively SIMPLE in use).

note *: an instantiated set of individuals and their properties can be regarded as a class. So one actually applies a closure axiom on the (new) instantiated class, right?