Talk:Filtration (mathematics)

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Sigma-algebra case

The concept is more general than the sigma-algebra case, though.

Charles Matthews 08:28, 15 Jun 2004 (UTC)

Not that I know of, so feel free to expand the article to the general case. Bryan Barnard 12:29, 3 Jul 2004 (UTC)

Need clarification

There appears to be an anomaly in the article. The definition mentions

"... subject only to the condition that if i ≤ j in I then Si is a subset of Sj"

whereas in the groups subsection of Examples in Algebra mentions

"A filtration of a group G, is then a sequence Gn of normal subgroups of G which is decreasing in the sense that for any n, we have Gn+1 ⊆ Gn."

According to the first statement, it should have been Gn ⊆ Gn+1.

Tsachin 13:16, 16 May 2007 (UTC)Tsachin[reply]

Let I be N with the reverse ordering. You get the same concept. Joeldl 13:47, 16 May 2007 (UTC)[reply]

Is the definition of filtration given in the "Groups" section the "only" definition in this context? It seems like a decreasing sequence of subgroups (not necessarily normal) or an increasing sequence of (normal) subgroups would also be consistent with the general definition given in the introduction. Are these also considered filtrations? ATC2 (talk) 18:11, 15 March 2011 (UTC)[reply]

I-stable module filtrations

It would be nice to have some mention of I-stable module filtrations (for some ideal I), and how any two I-stable filtrations have bounded difference and hence induce the same topology (which is, of course, the I-topology). 128.148.41.116 (talk) 23:39, 5 May 2008 (UTC)[reply]

That is the Artin-Rees lemma. Joeldl (talk) 06:44, 6 May 2008 (UTC)[reply]

Modal logic connection?

I have come across filtrations in proofs of the decidability of modal logics (in Chellas's book, e.g.). Are they an example of the same thing? — Preceding unsigned comment added by 81.131.24.208 (talk) 17:14, 30 January 2013 (UTC)[reply]

Right-continuous filtration

Is it still right if $t\in \{0,1,\dots ,\infty \}$ ? The whole idea is in infinitesimal increase. --Igor Yalovecky (talk) 15:12, 5 February 2018 (UTC)[reply]