Talk:Formal concept analysis

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What about unicorns? Concept, yes, but extension, no.

1. Formal concept analysis is about formal concepts in respect to a formal context. The only concept, which may have empty extent is the bottom concept, which always has the entire attribute set as intent.

2. Talking (non-formally) about unicorns leads to a concept in a fantasy setting, which provides imaginary objects to the "real world". So the concept unicorn has a (non-empty) extension. Excluding imaginary objects from "real wolrd" leads to a concept, too, but it is usually not useful to call it unicorn.

[edit] WTF is Formal Concept Analysis?

I actually know Lattice Theory out the wazoo, but I still fail to understand what this article is about. Does anyone care to shed any light on the subject? In particular, what is the purpose of this subject? How is it useful? Why is it interesting enough that people have written books and articles on it? It seems vaguely interesting but the current article doesn't really communicate the usefulness or purpose of this subject. Cazort 21:40, 23 October 2007 (UTC)

My naive understanding is that's a principled way of automatically deriving an ontology from a collection of objects and their properties. So it's useful to the extent that ontologies are useful more generally and to the extent that the properties are easier to define and derive than the full ontology. —David Eppstein 22:21, 23 October 2007 (UTC)

Can anyone help fix Sample exclusion dimension? Michael Hardy (talk) 16:55, 28 March 2008 (UTC)

I think the definitions there are unambiguous. What's left out is why you should care; for that I guess you need to refer to the Valiant article (which I haven't yet done). But it has little or nothing to do with formal concept analysis. A concept in that setting is a subset of a given domain; the difficulty of learning a concept is the number of membership queries you have to do to distinguish it from all other concepts in a concept class; and the exclusion dimension is the difficulty of the hardest concept in the class. —David Eppstein (talk) 06:33, 29 March 2008 (UTC)