Graph Literals and Monads - was: Blank nodes must DIE! [ was Re: Blank nodes semantics - existential variables?]

> Begin forwarded message:
> 
> From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
> Subject: Re: Blank nodes must DIE! [ was Re: Blank nodes semantics - existential variables?]
> Date: 27 July 2020 at 20:56:26 CEST
> To: Maxime Lefrançois <maxime.lefrancois@emse.fr>, "Shaw, Ryan" <ryanshaw@unc.edu>
> Cc: Hugh Glaser <hugh@glasers.org>, Semantic Web <semantic-web@w3.org>
> Resent-From: semantic-web@w3.org
> 
> Le 27/07/2020 à 18:52, Maxime Lefrançois a écrit :
>> If we imagine datatypes that encode RDF graphs,
> 
> Ivan Herman drafted a document a while ago that does exactly that:
> 
> https://www.w3.org/2009/07/NamedGraph.html#definition-of-graph-literals

Great find. Thanks, I was not aware of that.

> I even think that, in some cases, it could be of some usefulness, but the kinds of use cases are so niche, and the idea of encoding RDF graphs inside literals in other RDF graphs is so disturbing to the homo semanticus that there are chances it will never get traction.

I think that RDF graph literals are the best way to explain how a simplified
”named graphs” were there all along in RDF, and in fact cannot be avoided. 
(as I understand named graphs can share blank nodes (oops here they are agin!), 
and that would not have been possible with graph literals).

It actually gives just the right level of opaqueness to those objects. A graph
literal can be talked about without accepting the content. To accept the content
one has to declare the literal to be true.

That is a well known way Donald Davidson used Tarski’s Convention-T to explain
meaning for a disquotational view of truth.

   ”Snow is white” is T iff Snow is white.

But one need not remove the quote if one does not believe the content to 
be true.

So this allows one to say that (I did not put the full urls that would 
be needed to avoid tedium)

:joe said ”:tim foaf:known :jane”^^iana:Turtle

And with the says_that relation one gets the basic modal logic
developed by Abadi, and which he argues is Monadic

"Access Control in a Core Calculus of Dependency"
https://www.sciencedirect.com/science/article/pii/S1571066107000746

(These are the Monads initially loved so much by Functional 
Programmers, and now spreading to every programming language.
Monads allow FP to capture a notion of context).



> --AZ
> 

Henry Story

https://co-operating.systems
WhatsApp, Signal, Tel: +33 6 38 32 69 84‬ 
Twitter: @bblfish

Received on Monday, 27 July 2020 22:23:09 UTC