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What Is a Knowledge Graph?

neo4j.com

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Re: What Is a Knowledge Graph?

#11

Post by andersonvaz »

kmerroll wrote: post #4

Good article on the high level concepts of a knowledge graph, but some concerning mischaracterizations of core functions of ontologies supporting the class schema and continued disparaging of competing standards-based (RDF triple-store) solutions. That the author omits the updates for property annotations using RDF* is probably not an accident and glosses over the issues with their proprietary clunky query language.…

Do you mind in mentioning some of the options available that you consider better than Cypher?

Re: What Is a Knowledge Graph?

#12

Post by nemo44x »

What's great about knowledge graphs and property graphs in general is once you really get it (and it's not too difficult, especially if you come from a CS background) you start to see graphs all over the place. It's a really nice way to work with data for certain classes of problems. Once you get "enough" data in and "enough" of a variety of things connected, you start to see remarkable relationships emerge.

Re: What Is a Knowledge Graph?

#13

Post by CharlieDigital »

kmerroll wrote: post #4

Good article on the high level concepts of a knowledge graph, but some concerning mischaracterizations of core functions of ontologies supporting the class schema and continued disparaging of competing standards-based (RDF triple-store) solutions. That the author omits the updates for property annotations using RDF* is probably not an accident and glosses over the issues with their proprietary clunky query language.…

    > While knowledge graphs are useful in many ways, personally I wouldn't use Neo4J to build a knowledge graph as it doesn't really play to any of their strengths.
I'd strongly disagree. The built-in Graph Data Science package has a lot of nice graph algos that are easy to reach for when you need things like community detection.

The ability to "land and expand" efficiently (my term for how I think about KG's in Neo4j) is quite nice with Cypher. Retrieval performance with "land and expand" is, however, highly dependent on your initial processing to build the graph and how well you've teased out the relationships in the dataset.

    > I would rather stab myself with a fork than try to use Cypher to query a concept graph when better standards-based options are available.
Cypher is a variant of the GQL standard that was born from Cypher itself and subsequently the working group of openCypher: https://opencypher.org/

More info:

https://neo4j.com/blog/gql-international-standard/

https://neo4j.com/blog/cypher-gql-world/

Re: What Is a Knowledge Graph?

#15

Post by burakemir »

In addition to labelled property graphs and triples, a list of approaches to knowledge graph should consider facts(tuples) that are connected via common values as a form of graph, with datalog queries to query them. This is a lot more flexible than either approach IMHO and also more easily connected to existing relational data.

RDFox is a tool that uses Datalog internally. RelationalAI uses a datalog based approach. Another example is Mangle Datalog, my own humble open source project that can be found on GitHub.

The language in the article about relational being "non native graph" is a bit biased. With some developer attention, there are massive opportunities to store data in a distributed manner and with te right indices querying can be fast. Though to be fair, good performance will always need developer attention.

Re: What Is a Knowledge Graph?

#16

Post by cobertos »

nemo44x wrote: post #12

What's great about knowledge graphs and property graphs in general is once you really get it (and it's not too difficult, especially if you come from a CS background) you start to see graphs all over the place. It's a really nice way to work with data for certain classes of problems. Once you get "enough" data in and "enough" of a variety of things connected, you start to see remarkable relationships emerge.

What sort of relationships have you seen in the data you've worked with that you'd describe as remarkable?

I've explained a similar thing to friends before, but I was always at a loss for relationships/insights that have led to concrete outcomes

Re: What Is a Knowledge Graph?

#17

Post by nemo44x »

cobertos wrote: post #16
nemo44x wrote: post #12

What's great about knowledge graphs and property graphs in general is once you really get it (and it's not too difficult, especially if you come from a CS background) you start to see graphs all over the place. It's a really nice way to work with data for certain classes of problems. Once you get "enough" data in and "enough" of a variety of things connected, you start to see remarkable relationships emerge.

What sort of relationships have you seen in the data you've worked with that you'd describe as remarkable? I've explained a similar thing to friends before, but I was always at a loss for relationships/insights that have led to concrete outcomes

Supply chain and logistics. We’d start to see where the biggest risk points were and use that to diversify risk and also rank failover. We could make predictions about how the supply chain would be disrupted based on individual suppliers/movers/warehouses/etc having events that affected their ability to perform. You start to see how much some suppliers rely on each other, etc. Holy hell did Covid make that crazy!

Re: What Is a Knowledge Graph?

#18

Post by CharlieDigital »

enragedcacti wrote: post #10
kmerroll wrote: post #4

Good article on the high level concepts of a knowledge graph, but some concerning mischaracterizations of core functions of ontologies supporting the class schema and continued disparaging of competing standards-based (RDF triple-store) solutions. That the author omits the updates for property annotations using RDF* is probably not an accident and glosses over the issues with their proprietary clunky query language.…

> That the author omits the updates for property annotations using RDF* is probably not an accident and glosses over the issues with their proprietary clunky query language. Not just that, w.r.t. reification they gloss over the fact that neo4j has the opposite problem. Unlike RDF it is unable to cleanly represent multiple values for the same property and requires reification or clunky lists to fix it.

    > clunky lists
Not sure what the problem is here. The nodes and relationships are represented as JSON so it's fairly easy to work with them. They also come with a pretty extensive set of list functions[0] and operators[1].

Neo4j's UNWIND makes it relatively straightforward to manipulate the lists as well[2].

I'm not super familiar with RDF triplestores, but what's nice about Neo4j is that it's easy enough to use as a generalized database so you can store your knowledge graph right alongside of your entities and use it as the primary/only database.

[0] https://neo4j.com/docs/cypher-manual/current/functions/list/

[1] https://neo4j.com/docs/cypher-manual/current/syntax/operator...

[2] https://neo4j.com/docs/cypher-manual/current/clauses/unwind/...

Re: What Is a Knowledge Graph?

#19

Post by westurner »

alexchantavy wrote: post #5
kmerroll wrote: post #4

Good article on the high level concepts of a knowledge graph, but some concerning mischaracterizations of core functions of ontologies supporting the class schema and continued disparaging of competing standards-based (RDF triple-store) solutions. That the author omits the updates for property annotations using RDF* is probably not an accident and glosses over the issues with their proprietary clunky query language.…

I enjoy cypher, it's like you draw ASCII art to describe the path you want to match on and it gives you what you want. I was under the impression that with things like openCypher that cypher was becoming (if not was already) the main standard for interacting with a graph database (but I could be out of date). What are the better standards-based options you're referring to?

W3C SPARQL, SPARUL is now SPARQL Update 1.1, SPARQL-star, GQL

GraphQL is a JSON HTTP API schema (2015): https://en.wikipedia.org/wiki/GraphQL

GQL (2024): https://en.wikipedia.org/wiki/Graph_Query_Language

W3C RDF-star and SPARQL-star (2023 editors' draft): https://w3c.github.io/rdf-star/cg-spec/editors_draft.html

SPARQL/Update implementations: https://en.wikipedia.org/wiki/SPARUL#SPARQL/Update_implement...

/? graphql sparql [ cypher gremlin ] site:github.com inurl:awesome https://www.google.com/search?q=graphql+sparql++site%253Agit...

But then data validation everywhere; so for language-portable JSON-LD RDF validation there are many implementations of JSON Schema for fixed-shape JSON-LD messages, there's W3C SHACL Shapes and Constraints Language, and json-ld-schema is (JSON Schema + SHACL)

/? hnlog SHACL, inference, reasoning; https://news.ycombinator.com/item?id=38526588 https://westurner.github.io/hnlog/#comment-38526588

Re: What Is a Knowledge Graph?

#20

Post by findthewords »

For me a knowledge graph is a complex network.

When you try to grasp any complex topic your brain starts to build and connect a fuzzy network of topics and their respective positive or negative correlations and of course the weights between the connections.

Once you have unfuzzied the picture in your head you realize that the network is active and dynamic and that this network has different "modes" of operation and that some weights and correlations can change over time, while others are always static.

Mastering the dynamics of the knowledge graph is the final step in understanding it.

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