Talk:Projective hierarchy

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This used to be a redirect to analytical hierarchy, but that doesn't make any sense as "analytical" is a lightface notion, whereas "projective" is boldface. This page and analytic set are candidates for a future merge into the pointclass page, when I get that written. --Trovatore 8 July 2005 06:19 (UTC)

Requested move

Projective set → Projective hierarchy

There's no sense in having both articles, and the "hierarchy" title better reflects the content. --Trovatore 06:56, 31 March 2007 (UTC)[reply]

Done. CMummert · talk 14:02, 31 March 2007 (UTC)[reply]

I think it is nice to have a separation between X hierarchy and X set. For example:

Arithmetical hierarchy / Arithmetical set

Analytical hierarchy / Analytic set

Borel hierarchy / Borel set (= Borel algebra)

There is a little duplication of content, but I think it is helpful to a naive reader to start with the non-hierarchy definition and later learn about the stratification. CMummert · talk 14:06, 31 March 2007 (UTC)[reply]

Well, you can make a case for that, but it does make maintenance and improvement more difficult. (By the way the "analytical hierarchy/analytic set" juxtaposition is wrong.) --Trovatore 16:37, 31 March 2007 (UTC)[reply]

The Lightface and darkface page is still unwritten. Not being a descriptive set theorist, I tend mentally identify the corresponding hierarchies. CMummert · talk 17:18, 31 March 2007 (UTC)[reply]