Land as subclass or part of

[Garybc]

Should "land" have a part-of relation to "solid surface layer" rather than being a subclass?

[wdduncan]

I think it depends on how you define "layers" within the ontology. EnvO defines layer as:

A layer is a quantity of some material which is spatially continuous, has comparable thickness, and usually covers some surface.

So, IMHO, land fits as a subclass. But, I think I see why you are suggesting a part-of relation. In general, material entities can have other material entities as parts. So, it might make sense to assert that land is part of a solid surface layer. However, do you have a use case in which including the part-of axiom would add value (i.e., you couldn't get the same information using the subclass relation)?

[dr-shorthair]

"and usually covers some surface" isn't quite right. More like "and usually extends across a significant fraction of some surface" though this still does not quite work for sub-surface layers (e.g. geological strata).

[pbuttigieg]

@Garybc

Should "land" have a part-of relation to "solid surface layer" rather than being a subclass?

Thanks for raising this, but please concisely explain your thinking for this to move forward.

Following on from @wdduncan's points, I can also see arguments for both. But if it's a part of something, what is that something? The solid surface of an astronomical body?

Perhaps land is too colloquial and shouldn't be under layer at all, as extrusions or uplifts (which are not layer-like) are also considered land.

@dr-shorthair

"and usually covers some surface" isn't quite right. More like "and usually extends across a significant fraction of some surface" though this still does not quite work for sub-surface layers (e.g. geological strata).

Agreed, maybe this is extraneous entirely

[Garybc]

Here is a proposed way of handling this by revising the definition by removing the last part. Simplify the current definition for land : A surface layer of an astronomical body which is primarily composed of solid material. and is not covered by oceans or other bodies of water. Then distinguish 2 sub-classes of land - that surround by air (terrestrial land) and that below water (underwater land). Boht are a solid surface layer and part of the crust.

Gary Berg-Cross Ph.D. Consultant Potomac, MD 240-426-0770

On Tue, Mar 9, 2021 at 1:23 PM Pier Luigi Buttigieg < @.***> wrote:

@Garybc https://github.com/Garybc

Should "land" have a part-of relation to "solid surface layer" rather than being a subclass?

Thanks for raising this, but please concisely explain your thinking for this to move forward.

Following on from @wdduncan https://github.com/wdduncan's points, I can also see arguments for both. But if it's a part of something, what is that something? The solid surface of an astronomical body?

Perhaps land is too colloquial and shouldn't be under layer at all, as extrusions or uplifts (which are not layer-like) are also considered land.

@dr-shorthair https://github.com/dr-shorthair

"and usually covers some surface" isn't quite right. More like "and usually extends across a significant fraction of some surface" though this still does not quite work for sub-surface layers (e.g. geological strata).

Agreed, maybe this is extraneous entirely

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