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Re: Monotonicity of semantic extensions

From: Richard Cyganiak <richard@cyganiak.de>
Date: Wed, 12 Sep 2012 17:30:38 +0100
Cc: Antoine Zimmermann <antoine.zimmermann@emse.fr>, public-rdf-wg@w3.org
Message-Id: <9FB4FFEA-859B-4D5E-8685-4C99AADA77AA@cyganiak.de>
To: Peter F. Patel-Schneider <pfpschneider@gmail.com>
On 12 Sep 2012, at 16:31, Peter F. Patel-Schneider wrote:
>>> With the direct graph semantics you propose, it is a non-monotonic extension because when you switch this semantics on, the entailments you could do with the "minimal" semantics are not valid anymore.
>>> I don't think that's how people think of an extension. They probably do not expect that extensions make you lose what you had before.
>> Well, yes, there are cases where the minimal semantics says that A entails B, and the “direct graph” semantics says that A contradicts B.
> 
> Note that this last statement does not in itself indicate that there are entailments in the minimal semantics that are not entailments in the direct graph semantics.   It could just be the case that A is inconsistent in the direct graph semantics.

No, there are indeed cases here where A is consistent under either semantics, A entails B in the minimal semantics, and A contradicts B in the stronger semantic extension.

Does that make the semantic extension non-monotonic?

Richard
Received on Wednesday, 12 September 2012 16:31:12 GMT

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