Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Ask HN: What happened to the semantic web?

news.ycombinator.com

Post reply on HN
Print view View original

61–70 of 72 posts

Re: Ask HN: What happened to the semantic web?

#61

Post by sgt101 »

I had a project where we wanted a ticketing / events ontology and budgeted 6 weeks for three people to build it, in the end we spent probably 3 person years on it, which was dim... but we got suckered in by the idea that the ontologies themselves would be valuable (spoiler - nope).

So, knowledge engineering scales badly, but there were other problems. There was a big debate in the EU community about what kind of reasoner to use, and for some god awful reason F-logic was chosen, at the time we thought that reasoners like Otter wouldn't be able to scale and do FOL tractably. It's a shame that answersets and MCMC probalistic reasoners were 10 years later - I think that the weak reasoning and poor representation systems were big gaps.

The other problem was institutional, the way that EU semantic web funding worked, and the way that the projects developed. A lot of money was spent, and then there was no money - there was no self sustaining legacy.

Re: Ask HN: What happened to the semantic web?

#62

Post by icebraining »

drcode wrote: post #59
icebraining wrote: post #29

Earlier quoted context omitted.

But RDF was pretty good with that, because it didn't force records into hierarchies. You could just define relationships, and then create them freely between records. Some people created heavy ontologies, but it wasn't a result of the data model.

Right, but the whole dream of the "semantic web" to me was that one website could discuss red wines, and another website could discuss Vietnamese food, and then a reader could use the semantic vocabulary shared between the two sites to arbitrarily ask questions such as "what wine will go best with this dish?" If you just have a vocabulary where everyone can freely define concepts and their relationships in a fuzzy wa…

Right, the vocabularies were supposed to be reused as much as possible, but that doesn't require heavy hierarchies, just that they were available. A single record could have facts/relationships defined by any number of ontologies, so they didn't have to be all-encompassing either.

Also, I think there were ways to "map" different ontologies, thought I never really explored that.

Re: Ask HN: What happened to the semantic web?

#64

Post by naasking »

AndrewDucker wrote: post #48
naasking wrote: post #31

Earlier quoted context omitted.

> don't map neatly onto mathematically-sound hierarchies. I think they do, but finding the right mathematical model is very difficult. If it were easy, everyone would be a mathematics PhD. Learning to program is becoming efficient at recognizing the right spherical cow in any given situation, because such shortcuts are essential to getting shit done.

Are viruses alive? (To pick one question where something doesn't map onto a hierarchy simply)

Precisely define "alive" and you'll have your answer.

Re: Ask HN: What happened to the semantic web?

#65

Post by naasking »

drcode wrote: post #60
naasking wrote: post #31

Earlier quoted context omitted.

> don't map neatly onto mathematically-sound hierarchies. I think they do, but finding the right mathematical model is very difficult. If it were easy, everyone would be a mathematics PhD. Learning to program is becoming efficient at recognizing the right spherical cow in any given situation, because such shortcuts are essential to getting shit done.

I think you'd change your tune (like I did) once you dig into the ugly details of such mathematical modeling. A book like this will show you just how hard this is https://www.amazon.com/Knowledge-Representation-Reasoning-Ar...

I recognize it's difficult since I literally said that. But programming is simplified mathematical modelling of a sort (for instance, via Curry-Howard), hence my "spherical cow".

Re: Ask HN: What happened to the semantic web?

#66

Post by naasking »

TeMPOraL wrote: post #57
naasking wrote: post #31

Earlier quoted context omitted.

> don't map neatly onto mathematically-sound hierarchies. I think they do, but finding the right mathematical model is very difficult. If it were easy, everyone would be a mathematics PhD. Learning to program is becoming efficient at recognizing the right spherical cow in any given situation, because such shortcuts are essential to getting shit done.

I disagree. It all boils down to the way we use language - words have meanings, but those meanings are just pretty fuzzy boundaries in conceptspace. It seems that words represent concrete things from a distance, but if you look closely, it all breaks down. Hell, the meaning of words also heavily depends on context in communication, so they can paint barely overlapping borders in conceptspace from one conversation to…

I'm not sure that you disagreed with anything I said.

Re: Ask HN: What happened to the semantic web?

#68

Post by Shamanmuni »

drcode wrote: post #25

I think the main issue is that even though "knowledge representation" with ontologies is an enticing goal, it's simply a fact that real entities, as used by humans at a practical level, don't map neatly onto mathematically-sound hierarchies.. . To see this, just look at the arguments the ancient Greeks already had as to whether a human is a "two-legged featherless animal" or the endless online arguments as to whether…

I suppose you're talking about OWL. The thing is most programmers look at OWL, see the words class and property and immediately think that it's OOP, that they don't have to look more into it and it has the same problems.

But OWL is not based on OOP, it's based on Description Logic, which is a much more powerful abstraction than OOP and it let's you easily represent things which are very hard with something like Java. OWL includes the concept of complex class, in which you define the logical constraints of the class and then it is inferred automatically by a reasoner. This means that you can build really complex multidimensional hierarchies pretty easily.

For example, you can solve the circle/ellipse this way: the class circle is a complex class which is the intersection of the class ellipse and the class of two dimensional geometric shapes in which both major and minor axis have the same length. Any object that satisfies those constraints is a circle!

About the greek problem: you have to declare that the human class and the complex class which results from the intersection of the class two-legged animal and featherless animal are equivalent. It means that every human is two-legged featherless animal and viceversa.

You can even declare equivalences between ontologies, which lets you build conceptual bridges.

OWL has problems related with the maturity and performance of its implementations, and it remains to be seen if it's possible to treat the web as a gigantic Prolog program, but its conceptual model is powerful and sound.

Re: Ask HN: What happened to the semantic web?

#69

Post by hacknat »

The simple reason is that people are lazy. Someone isn’t going to put in the extra work of marking up their text with the correct semantic structure if they don’t get much out of it, and the ROI for an individual site owner was dubious at best. People keep talking about RFD, but that barely qualifies IMO, it was more of an agreed upon RFC so that search engines didn’t force site owners to all adopt differing indexable formats (events, addresses, etc). Even with the backing of Google, RFD is not something that most sites are doing until they start tackling some enterprise grade SEO optimizations.

Re: Ask HN: What happened to the semantic web?

#70

Post by Eli_P »

What about NIEM (National Information Exchange Model) [1][2].

I see this tech is supposed to be replacement for paper documents and be the medium for government information arbitrage. The only obstacle for using it everywhere is structural complexity of NIEM and lack of tools. I've spent a bit of time hacking it with XML queries and my mind is blown [3].

You can interpret NIEM as a type system similar to types in programming languages, but for composing electronic documents; it could be integrated with payment systems. I think progress will go two ways: composing new documents will be happening with NIEM, older docs could be converted with natural language processing.

The latest version 4.0 is dated 2017, and US has spent lots of money to build an XML representation of real-life objects.

[1] https://www.niem.gov/ [2] https://en.wikipedia.org/wiki/National_Information_Exchange_... [3] https://github.com/NIEM

Post reply on HN