[topicmapmail] Zero or more roleplayers in XTM 1.0.1

[Kevin Johnson]

The null or empty set is considered to be a subset of every set.*

*Seymour Lipschutz in "Set Theory and Related Topics,"  New York: McGraw
Hill, 1964, page 3.  My copy of Quine's "Mathematical Logic" is kicking
around here somewhere; says the same thing.


----- Original Message -----
From: "Lars Marius Garshol" <larsga@garshol.priv.no>
To: <topicmapmail@infoloom.com>
Sent: Thursday, November 14, 2002 8:43 AM
Subject: Re: [topicmapmail] Zero or more roleplayers in XTM 1.0.1



* Steve Pepper
|
| It was always the intention that it should be possible to specify a
| role without specifying the role players. The rationale is to be
| able to represent incomplete knowledge. (I know Marc is married, but
| I don't know who his wife is...)

Do note, however, that the decision we made in Montréal was that in
these cases blank topics will be created on deserialization. So what
this means is that leaving out the topic reference is a shorthand for
creating a topic with no characteristics.

In LTM, which does not support this, this is what we've usually done
in the cases where we have not known the player of a role.

<URL:
http://www.ontopia.net/omnigator/models/topic_complete.jsp?tm=tm-standards.x
tm&id=assoc-role-player-type >

--
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
ISO SC34/WG3, OASIS GeoLang TC        <URL: http://www.garshol.priv.no >