The Semantics Are Important

Stefan Plantikow asks a good question:

> But isnt it absurd or at least meaningless to believe we are talking about the same “uri-wise” thing iff we put “it” into completely different classes? What does such an identity establish at all?

I don't think it's meaningless at all. Think about how we talk about things in the real world.

Q: "Where are you going this weekend?"
A: :Seth :travelsTo [geo:lat "123"; geo:long "456"];

OK, so now we have a bnode for some location. That is unambiguous as far as I'm concerned, as there's only one Point on Earth with that lat and long.

Now, here's my point about the difference between identity and meaning. The identity is singular. The meaning is relative. Let's think about all the different meanings we can associate to that identity.

[geo:lat "123"; geo:long "456"] a :Beach.


[geo:lat "123"; geo:long "456"] a :CountyPark.


[geo:lat "123"; geo:long "456"] a :Ocean.

All of the above would work in the real world. You can easily answer the question, "I'm going to the beach" or "I'm going to the park" or "I'm going to the ocean" and we know you mean the same thing. The real world is that flexible, so the semantic web must allow for this type of flexibility.

Now, this is where Semantics comes in. When you say "ocean", you might mean "Something with sand, next to the ocean, where people hang out, where you can swim". Again, the identifier for the class :Ocean is what is globally unique. But the definition of :Ocean is context specific.

Thinking about it, it happens that your definition of :Ocean (above) matches perfectly with my definition of :Beach ("Something with sand, next to the ocean, where people hang out, where you can swim"). And this is where the semantic web shines... when you say :Ocean and I say :Beach, we can reason we are talking about the same type of thing.

If we apply our contextual definitions (semantics) to the Thing in question (here it is [geo:lat "123"; geo:long "456"]) then we are at least talking about the same thing. This is the important part about the whole operation. No matter how we define that location on earth, it's the same location between the both of us.

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