Hi Sean & Bob,
Your emails were making it through to the tech list.
see: https://lists.spdx.org/g/Spdx-tech/message/5277
To look and see the ones that have been posted this month
see: https://lists.spdx.org/g/Spdx-tech/messages?start=8:2023:300
Thanks,
Kate
On Wed, Aug 2, 2023 at 2:51 PM Martin, Robert A <[email protected]> wrote:
> And this one also doesn't seem to have made it to the list.
>
> Bob
>
> *From: *Sean Barnum <[email protected]> <[email protected]>
> *Date: *Tuesday, August 1, 2023 at 2:06 PM
> *To: *[email protected] <[email protected]>
> <[email protected]>
> *Subject: *FW: Some fodder for the discussion of blank nodes
>
> I just noticed that this has still not shown up in my inbox though it
> looks like it made it out of my outbox.
>
> This is the email I was referring to during the call thinking that you all
> had it already.
>
> Sorry about that.
>
>
>
> Hopefully it makes it past the spdx list server this time.
>
>
>
> sean
>
>
>
> *From: *Sean Barnum <[email protected]> <[email protected]>
> *Date: *Tuesday, August 1, 2023 at 11:50 AM
> *To: *[email protected] <[email protected]>
> <[email protected]>
> *Subject: *Some fodder for the discussion of blank nodes
>
> All,
>
>
>
> I apologize for the lateness of this. I threw it together yesterday and
> sent it to the list but just noticed that it never left my outbox so I must
> have messed something up.
>
>
>
> This is a VERY simple overview of some of the aspects of blank nodes we
> should consider when discussing whether they should be used for SPDX 3.0
>
> It is VERY informal and quickly thrown together so please do not interpret
> it as anything too rigorous. Rather than me spending time writing up
> rigorous argumentation I instead took an approach of pulling together
> several reference links addressing various aspects and let those do the
> talking with only a simple summarization of the aspect issue from me.
>
>
>
> - Some VERY quick and short notes on the question of using blank nodes
> or not
> -
> - The below short outline includes several relevant links to resources
> on various aspects of this issue. All of these links were found within 20
> mins of very simple Google querying and all were within the first 5-10
> results for each Google query.
> -
> - There is broad consensus on the existence of significant issues and
> challenges with using blank nodes. 15-30 mins of googling will yield scores
> of papers, blog posts, articles, etc. calling out various reasons that
> blank nodes are problematic and should be avoided wherever possible in the
> large majority of situations. Defined semantics and specifications
> regarding Bnodes are inconsistent and contradictory leading to
> inconsistency between tools, ambiguity in how they will be processed,
> interpreted or queried.
>
>
> -
> http://richard.cyganiak.de/blog/2011/03/blank-nodes-considered-harmful/
> - https://aidanhogan.com/docs/blank_nodes_jws.pdf
> - https://marceloarenas.cl/publications/iswc11.pdf
> - https://terminusdb.com/blog/blank-nodes-in-rdf/
> - https://terminusdb.com/blog/blank-nodes-in-rdf/
>
>
> 1. When blank nodes are used it is typically for the convenience of
> the producer but often comes at significant cost to the consumer in the
> form of ambiguity, uncertainty, complexity, and resources (time and
> computing resources)
> 2. *IF* they are decided to be used they are *ONLY* for a single
> scope of a single datastore or single serialized document and *NOT*
> for global or cross-scope use. This is explicitly stated in all of the
> W3C
> specs dealing with Bnodes. Using them for cross-scope use as SPDX 3.0 is
> intended leads to significant potential data integrity issues.
>
>
> - https://www.w3.org/wiki/BlankNodes
> - https://www.w3.org/TR/rdf11-concepts/#section-blank-nodes
> - https://www.w3.org/TR/rdf-mt/#unlabel
> - https://en.wikipedia.org/wiki/Blank_node
>
>
> 1. Avoiding these significant potential issues typically requires
> skolemization (replacing the localized ids with globally unique IRIs) of
> the Bnodes. This extra effort is forced on the consumer and is often
> done
> by processors and graph stores as part of deserialization/ingestion.
> However, due to the inconsistencies in the specs regarding Bnodes this
> is
> not consistent. Some processors and stores do not perform skolemization
> an
> simply utilize the localized Bnode ids (especially if they are producer
> asserted in any way). This leads to significant integrity issues as
> these
> ids collide (simple example is even explicitly in some W3C docs/specs
> and
> on the Wikipedia page) and increases significantly with the volume of
> cross-scope content ingested. Skolemization also does not provide any
> id-related context for the source of the nodes such as that provided by
> namespaces in producer specified IRIs.
>
>
> -
>
> https://www.w3.org/2011/rdf-wg/wiki/Skolemisation#:~:text=Blank%20nodes%20do%20not%20have,are%20known%20as%20Skolem%20IRIs
> .
> - https://www.w3.org/wiki/BnodeSkolemization
>
>
> 1. Bnodes also have very significant issues for SPARQL, the definitive
> standard mechanism for querying rdf graphs. The two do NOT play well
> together at all due to inherent issues in Bnode design and
> inconsistencies
> in the rdf specs related to Bnodes. Many queries can lead to
> inconsistent
> and non-integrous results. Various academics and companies have offered
> workarounds and schemes to attempt to address this disconnect but they
> all
> come at significant compute complexity and cost. These issues increase
> significantly with the volume of Bnodes in the overall graph being
> queried.
>
>
> - https://www.w3.org/2009/12/rdf-ws/papers/ws23
> -
> https://aidanhogan.com/docs/certain_answers_sparql_blank_nodes.pdf
> - http://www.jsoftware.us/vol7/jsw0709-09.pdf
>
>
> 1. Bnodes also cause significant issues with semantic entailment
> (ability to determine full semantic integrity and correctness) of the
> graph. Entailment is required for any higher-order semantic inferencing
> and
> analysis. A couple of academics have offered papers that purport to
> mathematically prove that entailment using Bnodes is NPComplete though
> there is broad consensus that while it is likely possible it is almost
> always impractical and problematic.
>
>
>
>
>
> Sean
>
>
>
>
-=-=-=-=-=-=-=-=-=-=-=-
Links: You receive all messages sent to this group.
View/Reply Online (#5280): https://lists.spdx.org/g/Spdx-tech/message/5280
Mute This Topic: https://lists.spdx.org/mt/100489649/21656
Group Owner: [email protected]
Unsubscribe:
https://lists.spdx.org/g/Spdx-tech/leave/2656181/21656/1901338254/xyzzy
[[email protected]]
-=-=-=-=-=-=-=-=-=-=-=-
