Re: A few thoughts on RDF-star, Reification, and Labeled Property Graphs


I had no intention of appearing unbiased; I am sorry if I gave you that impression. My original message represents the Neptune team's view which is highly biased in favor of our customers. We believe that working towards our "OneGraph" vision will also be beneficial to the rest of the graph industry and graph community.

There are many ways to achieve "graph interoperability" since one is free to define what that term means. Around the time when we wrote our first OneGraph paper [1] we had come to the conclusion that implementing or representing one metamodel using another metamodel was not going to be an acceptable approach, particularly if it exposed details of both models to whoever is writing queries. There are several examples of this approach around in the graph industry. Instead, we wanted to go for the "native" approach where all the query languages are acting directly on a single stored graph. In order for us to do this, we need to improve the alignment between RDF and LPGs. This alignment does not need to be perfect, however, and we are not aiming at a future where RDF == LPG.

We have been tracking the RDF-star WG's progress against our formal model of OneGraph, mindful of what adjustments we need to make, but also where we need to "draw the line" if we cannot map RDF-star onto OneGraph. The "one reifier multiple triples" -proposal crosses that line.


[1] Ora Lassila, Michael Schmidt, Brad Bebee, Dave Bechberger, Willem Broekema, Ankesh Khandelwal, Kelvin Lawrence, Ronak Sharda, and Bryan Thompson: "Graph? Yes! Which one? Help!", 1st Workshop on Squaring the Circle on Graphs, SEMANTiCS 2021, Amsterdam, September 2021.

Dr. Ora Lassila 
Principal Technologist, Amazon Neptune 

On 4/11/24, 3:58 PM, "James Anderson" < <>> wrote:

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good evening ora;

> On 11. Apr 2024, at 21:29, Gregg Kellogg < <>> wrote:
>> On Apr 11, 2024, at 4:38 AM, Orange Lassila < <>> wrote:
>> Niklas,
>> What we are saying is that the “one reifier multiple triples” model will diverge RDF even more from LPGs, effectively preventing us from improving the alignment between the two graph models. This would be bad for the graph community at large. We are not saying what RDF-star is; this is a community process, and the WG will choose its own direction. What we are saying is the direction the current proposal suggests will harm the broader graph community at the expense of adding a feature the use cases of which could be satisfied using the simpler model as well.
> RDF-star already is a superset of LPG in the sense that annotations can have their own annotations, and annotations can be entity relationships in addition to scalar attributes. Allowing a many-to-many reifier doesn’t seem like it would be the straw that breaks the camels back. For me, they key is to have a way to represent LPG in RDF-star, which I believe we can do, not necessarily to allow any RDF-star graph (not to mention dataset) be represented as an LPG. RDF already has greater expressivity than LPGs, and this would be just one more way in which RDF can represent more relationships.
> [...]

as unbiased as you may have intended your few thoughts to have been received, that has not been the universal perception.

in order to better understand what you would like this group to achieve, would you please explain what aspects of the situation gregg's assessment misses?

best regards, from berlin,
james anderson | <> | <>

Received on Friday, 12 April 2024 04:36:55 UTC