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Re: [ontolog-forum] a skill of definition - "river"

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Александр Шкотин <alex.shkotin@xxxxxxxxx>
Date: Thu, 12 Feb 2009 17:13:35 +0300
Message-id: <b24945a10902120613gb870b7btbd4790571be53abf@xxxxxxxxxxxxxx>


According to that definition the Okavango is not a river.


I think it's better to ask the author of definition. If you see Okavango as a counterexample.

I can do it, but I don't know Okavango;)

Anyway there is a chance to make definition better, or to get more about a topographical point of view;)


So it is a good example around the issues. Are stretches really "Parts"

of a river for example?

I guess it's possible to set out too many characteristics of something,

rather than just those things which, by virtue of being true of an

individual, make it a member of that class of thing.


You are right about "characteristics", but parts are very important, and for many artificial (and simple natural) things they give definition.

This is the case with some mixtures of molecules we buy to eat (sometimes they wrote these parts on the envelope;) and all thechnological things, when we define a thing (or process) independently or as part of.

Have a look at definition in "description" field for "pump":


and eliminating unnecessary loops...:

"A physical object that is a driven piece of equipment in which energy is either constantly or periodically added to an amount of liquid in order to increase the pressure required for the process of moving liquid in determinate direction."

Do we have a formal language for this kind of statements? - Yes and not one. For ex. RDF may syntactically "eat" everything, especially with reification technique.

Do we have inference rules (may I say "Figures of the Syllogism";) for this language to prove this kind of lemma: "Pump P1 cannot lift water on 10 meters."?

- I don't know. But on my knowledge, DL-reasoner, for ex., has only two services: subsumption checking and to check belongness.

Then we need a lot of logical axioms to reduce different kind of inference rules to these two services.

Well, in math-logic modus ponens is enough somehow. But it more reminds Sheffer operation.

So, where Linguist stops with all broadly used meanings discovered and defined, Logician begins clarifying definitions and discovering axioms and inference rules.

what do you think?

But back to "river".

for me informal definition as #1a at http://www.merriam-webster.com/dictionary/river

" a natural stream of water of usually considerable volume."

sound valuable to begin with, but we just should keep in mind that usually informal definitions are overlaped.

like with this one (following m-w.com): brook = creek#2 == "a natural stream of water normally smaller than and often tributary to a river"

But good news is that a number of sub-definitions about natural stream of water is fixed and small;)


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