IMO the most interesting place right now for semantic web development is Wikidata. It's still pretty difficult for newcomers to contribute (as is the case for all Wikimedia projects) but at least it has many eyeballs and a very active community / ecosystem.
There are lots of useful WIKIDATA links and demos on this page: https://www.wikidata.org/wiki/User:Daniel_Mietchen/FSCI_2017...
They are all nice ideas, but the practical usecases are rare. I am skeptical of the often touted usecase in Medicine/Drug Interactions. The only time i saw it in the industry, it was not really used by the lab technicians. Because all questions the system could answer, were trivial. The promise of "the system can inference new combinations/interactions" was never fulfilled.
The second biggest is possibly WikiData, and it is not that small.
As to the practical use cases, there are many, but it is the premier way of encoding metadata for search engines: https://schema.org/docs/about.html
And the amount of datasets and ontologies that exist is quite vast:
- https://lod-cloud.net/dataset
- https://www.mediawiki.org/wiki/Wikidata_Query_Service/User_M...
I would like to understand what other options you would consider better for these datasets, for the metadata and for the ontologies?
I mean if not RDF for web metadata then what? If not semantic web for UK govt data (https://ukparliament.github.io/ontologies/, https://opendatacommunities.org/data_home, https://ckan.publishing.service.gov.uk/dataset?res_format=RD..., https://ckan.publishing.service.gov.uk/dataset?res_format=SP...) then what?
It would be nice to have something even better, but I much prefer RDF to a bunch of CSV files.
So it's a lot of extra work to sift through, but I've found a lot of gold in there.
If you're looking for a simple, noise-free way to do the semantic web, I'm very confident that Tree Notation will enable it (https://treenotation.org/).
I've played around a bit with turning Schema.org into a Tree Language, and think that would be a fruitful exercise, but plenty more on the plate first.
FWIW I've pitched this concept to W3C for 4 or 5 years to no avail yet. I think though if someone can put together a decent prototype the idea might start clicking.
Imagine a noise free way to encode the semantic web with natural 3-d positional semantics. Could be cool!
My take with ontologies is building consensus is hard.
Tree Notation offers a solution to the problem of: what should we agree on for the encoding? I assume that simpler is better, all else being equal. Then Tree Notation is the simplest, in terms of the thing with the fewest pieces(tokens).
To get to Tree Notation, nothing was added, only stripped. I started with an existing notation and stripped away each visible syntax token that wasn't needed. Surprisingly, not one is needed. Not one quote, parens, bracket, colon, etc.
So now if we can get consensus around going with the simplest thing, we have got a way to agree on an whether we should use XML, JSON-LD, turtle, etc. The simplest thing works (which would be Tree Notation, or a close relative—someone can rebrand the notation but the idea is largely the same). This does not suffer from the 927 problem, as there are a few classes of things where we do have 1 new language that is mathematically superior and of a different kind than others (binary notation, for example).
So after you have agreement on that encoding, versioning and forking and merging schemas is dead simple (just use Git—in Tree Notation all changes are semantic and noise free).
So now we've solved what encoding to use for our ontologies, and we have a very fast and efficient way to collaborate on them (it's just plain text and git).
That brings us to a third advantage which is more theoretical. Tree Notation maps words/nodes to a 3-D representation. This means that there would be an X-Y-Z isomorphism with an ontology and the real world. I don't really know where we go from there, but at least by this point we've moved the semantic web idea a lot further and can start looking at the next realm of possibilities.