Why Rdf Is the Natural Knowledge Layer for AI Systems

My experience working with software developed by academics is that it is focused on getting the job done for a very small user base of people who are okay with getting their hands dirty. This means lots of workarounds, one-off scripts, zero regards for maintainability or future-proofing...

How so? Consider the famous result that most published research findings are false.

I just think that the idea of how to represent knowledge graphs is a topic that has hidden complexities in it that you need to make explicit.

My impression is that the mismatch comes from you get introduced to the idea of a triple just being a “subject, predicate and and object” and it’s incredibly simple but again, real life knowledge representation is a complicated thing and there’s a bit to unpack beyond that first impression.

  SELECT ?country (COUNT(*) AS ?stationCount) WHERE {
    ?station wdt:P31 wd:Q928830.
    ?station wdt:P17 ?country.
  }
  GROUP BY ?country
  ORDER BY DESC(?stationCount)
  LIMIT 1

which is not unreasonable as a quick first attempt, but doesn't account for the fact that many things on Wikidata aren't tagged directly with a country (P17) and instead you first need to walk up a chain of "located in the administrative territorial entity" (P131) to find it, i.e. I would write

  SELECT ?country (COUNT(DISTINCT ?station) AS ?stationCount) WHERE {
    ?station wdt:P31 wd:Q928830.
    ?station wdt:P131*/wdt:P17 ?country.
  }
  GROUP BY ?country
  ORDER BY DESC(?stationCount)
  LIMIT 1

In this case it doesn't change the answer (it only finds 3 more subway stations in China), but sometimes it does.

https://schema.org/Thing

RDF is one of those things it's easy to assume everybody has already encountered. RDF feels fundamental. Its predicate triplet design is fundamental, almost obvious (in hindsight?). It could not have not existed. Had RDF not existed, something else very similar would have appeared, it's a certitude.

But we might have reached a point where this assumption is quite false though. RDF and the semantic web were hot in the early 2000s, which was twenty years ago after all.

Yup, it's still that RDF. Inevitably, it had to be converted to new JSON-like syntaxes.

It reminds me of the "is-a" predicate era of AI. That turned out to be not too useful for formal reasoning about the real world. As as a representation for SQL database output going into a LLM, though, it might go somewhere. Maybe.

Probably because the output of an SQL query is positional, and LLMs suck at positional representations.

This is a non-trivial exercise. How does one transform knowledge into a knowledge graph using RDF?

RFD is extremely flexible and can represent any data and that's exactly it's great weakness. It's such a free format there is no consensus on how to represent knowledge. Many academic panels exist to set standards, but many of these efforts end up in github as unmaintained repositories.

The most important thing about RDF is that everyone needs to agree on the same modeling standards and use the same ontologies. This is very hard to achieve, and room for a lot of discussion, which makes it 'academic' :)

Here's the history of the Paris example: https://en.wikipedia.org/wiki/University_of_Paris where there was one, then many, then fewer universities. Answering a question of "what university is referred to by X" depends on why you want to know, there are multiple possible answers. Again it's not the weirdest one, but a good clear example of some issues.

There's a company called Merk, and a company called Merk. Merk is called Merk in the US but MSD outside of it. The other Merk is called Merk outside the US and EMD inside it. Technically one is Merk & Co and used to be part of Merk but later wasn't and due to trademark disputes, which aren't even all resolved yet.

This is an area I think LLMs actually have a space to step in, we have tried perfectly modelling everything so we can let computers which have no ability to manage ambiguity answer some questions. We have tried barely modelling anything and letting humans figure out the rest, as they're typically pretty poor at crafting the code, and that has issues. We ended up settling largely on spending a bunch of human time modelling some things, then other humans building tooling around them to answer specific questions by writing the code, and a third set who get to actually ask the questions.

LLMs can manage ambiguity, and they can also do more technical code based things. We haven't really historically had things that could manage ambiguity like this for arbitrary tasks without lots of expensive human time.

I am now wondering if anyone has done a graph db where the edges are embedding vectors rather than strict terms.

The more academic side will add more complexity to the modelling, trying to model it all.

The more business side will add more shortcuts to simplify the modelling, trying to get just something done.

Neither is wrong as such but I prefer the tendency to focus on solving an actual problem because it forces you to make real decisions about how you do things.

I think being able to build up knowledge in a searchable way is really useful and having LLMs means we finally have technology that understands ambiguity pretty well. There's likely an excellent place for this now that we can model some parts precisely and then add more fuzzy knowledge as well.

> The big question I still have is whether RDF offers any significant benefits for these way more limited scopes. Is it really that much faster, simpler or better to do queries on knowledge graphs rather than something like SQL?

I'm very interested in this too, I think we've not figured it out yet. My guess is probably no in that it may be easier to add the missing parts to non-rdf things. I have a rough feeling that actually having something like a well linked wiki backed by data sources for tables/etc would be great for an llm to use (ignoring cost, which for predictions across a year or more seems pretty reasonable).

They can follow links around topics across arbitrary sites well, you only need more programmatic access for aggregations typically. Or rare links.