I've been thinking a lot about rigid categories (clear-cut, well defined rules, often mutually exclsuve and/or hierarchical) and soft categories (fuzzy membership rules, rarely mutually exclusive or hierarchical).
It seems to me that we want not categories, but ''relations'' between objects, from which categories fall out as a consequence.
* Relations should be of the form x R y, where x and y are articles, and R is a relation-name. I propose a new namespace, Relation: for talking about relations. Notice that this makes it possible that x or y, or both, can also be relations!
The current link structure defines exactly one kind of relation: links-to
* Relations need not be equivalence relations, or even be reflexive or transitive.
* Now reserve a special syntax for putting relations into articles:
#relation [[article 1]] relation-name [[article 2]]
Note that article 1 or article 2 should be the name of the article that the line is written in: perhaps we could have a shorthand, 'this' for this article.
Now we can say things like:
#relation [[science]] is-a [[field of enquiry]]
#relation [[physics]] is-a [[science]]
#relation [[England]] subset-of [[Great Britain]]
#relation [[United Kingdom]] is-a [[nation state]]
#relation [[two]] is-a [[prime number]]
and so on...
It's ideal fodder for machine analysis (RDF can be generated naturally), and easy to parse and write. It's easy! It's wiki-style!
* Now comes the nice bit.
We can have meta-rules:
#relation [[relation:subset-of]] reverse-of [[relation:superset-of]]
#relation [[relation:subset-of]] more-important-for-sorting-than [[relation:member-of]]
#relation [[relation:identical-to]] is-a [[equivalence relation]]
Brainstorming...
* fuzzy relations:
#relation [[man]] indentical-to [[woman]] 0.85
* Bayesian inference on fuzzy rules...
-- Neil