2:08 AM
I guess the tag is intended for different meaning of the word filter than in: How can particle filter be implemented in practice? (A separate question is whether this question is on-topic here.)
0

I see that the multiple model method can be used without the knowledge of dynamic models, which usually happens in practice. But how can the particle filter be used when we don't exactly know the dynamic models?

4 hours later…
5:56 AM
The tags , and created back in July have been removed. As a result, Nambu Vinogradov bracket now has the tag . (At the moment this is the only such question on MathOverflow.)
6

Has there been any work on homotopy Nambu brackets or even better on strong homotopy Nambu brackets?? Ordinary Nambu brackets appear most recently in work of Takhtajan.

Let me just explain here in detail what happened here and how tag-pruning works.
Tags which have been used only on single question - and no other question has been added for a long time - are removed automatically by the system.
One exception is that if a tag has tag-wiki, then it remains only if there is only one question.
40

I don't know -- can anyone make a case for these single use tags existing for more than a month? edit: I am convinced this is a useful cleanup task, to remove these orphaned tags from the system automatically. I've implemented a routine that removes tags created more than 6 months ago which have...

> I am convinced this is a useful cleanup task, to remove these orphaned tags from the system automatically. I've implemented a routine that removes tags created more than 6 months ago which have been used only a single time. It will run monthly.
75

Single-use tags automatically expire after a few months. This is arguably the right thing when the tag is a misspelling (though I'd prefer some way of reviewing the process — but this post is not about that). However, if the tag was clearly deliberate, the default should be not to delete it. I pr...

So if somebody created a tag and they do not want it to disappear, they can either: 1. Created a tag-wiki for the tag. 2. Add it to more questions.
I will also mention that I have asked here in chat about these specific tags whether or not they are going to be useful: chat.stackexchange.com/… But I received no feedback on this.
6

Has there been any work on homotopy Nambu brackets or even better on strong homotopy Nambu brackets?? Ordinary Nambu brackets appear most recently in work of Takhtajan.

I think it would be useful if you could include a tag which wasn't created just for this question... — Wojowu Jul 31 '18 at 21:23
You might have noticed that the tags on your question have been removed and that it now only has the (untagged) tag. I have given a more detailed explanation what actually happend here in chat. — Martin Sleziak 23 secs ago

2 hours later…
7:38 AM
Another tag which was recently removed (probably by the same automated process) is : chat.stackexchange.com/transcript/10243/2018/8/10

1 hour later…
8:54 AM
Since I have mentioned the tag, I will add that SEDE returns 4 deleted questions with this tag: data.stackexchange.com/mathoverflow/query/883845/… There are 92 such questions on Mathematics: data.stackexchange.com/math/query/883845/…

3 hours later…
11:41 AM
0

The tags on convexity are convex-geometry ($\times$560), convex-analysis ($\times$ 266), convexity ($\times$ 420). Here the number is the current (2019/02/23) number of uses and I ignore some more specific tags whose meaning is quite well-identified such as convex-polytopes or convex-optimization...

7 hours later…
6:23 PM
Looking back at the posts and comments I have mentioned here, possibly I should have looked just at the ones containing research.att.com/~njas or maybe even research.att.com/~njas/sequences rather than just research.att.com/.

2 hours later…
8:21 PM
I see that I have forgotten to include a link. The above is related to these messages from a few days ago: chat.stackexchange.com/transcript/10243/2019/2/20

2 hours later…
10:09 PM
@MartinSleziak The OP removed (discrete-mathematics) and added (sequences-and-series). The question still has no top-level tag.
2

Given the base case $a_0 = 1$, does $a_n = a_{n-1} + \frac{1}{\left\lfloor{a_{n-1}}\right \rfloor}$ have a closed form solution? The sequence itself is divergent and simply goes {$1, 2, 2+\frac{1}{2}, 3, 3+\frac{1}{3}, 3+\frac{2}{3}, 4, 4+\frac{1}{4}, 4+\frac{2}{4}, 4+\frac{3}{4}, . . .$} and so ...

@MartinSleziak In this case, the OP changed (discrete-mathematics) to (fa.functional-analysis). (And the question was closed.)
0

I know that $f : R^n \xrightarrow{} R$ and $g : R^n \xrightarrow{} R$ are quasiconcave functions. How can I prove that the function $h(x)=\min\left\{f(x),g(x)\right\}$ is also quasiconcave? $\\$ $\\$ edit: (1) $f:D\xrightarrow{}R$ is quasiconcave if and only if the following holds for all $x... At the moment there are 873 questions with deprecated tags. This is the lowest number since I've started to pay attention to those tags. 10:25 PM @MartinSleziak So now the OP also added (nt.number-theory) - now the question has a top-level tag. (Probably some of the more experienced user might still check whether the choice of tags can be improved. 2 Given the base case$a_0 = 1$, does$a_n = a_{n-1} + \frac{1}{\left\lfloor{a_{n-1}}\right \rfloor}$have a closed form solution? The sequence itself is divergent and simply goes {$1, 2, 2+\frac{1}{2}, 3, 3+\frac{1}{3}, 3+\frac{2}{3}, 4, 4+\frac{1}{4}, 4+\frac{2}{4}, 4+\frac{3}{4}, . . .$} and so ... I might leave them there for a day or two - but prob ably I could at some point delete the comments about tagging I left at those questions. 10:52 PM Another question with deprecated tag was posted: Why do polynomials$x^n + 1 \bmod N$close a shorter cycle when$n$is even than when$n$is odd?. Simply remove the (abstract-algebra) tag? What would be a suitable top-level tag here? 0 Polynomials$p(x) \bmod N$, where$p(x)$is of integer coefficients and$N$is a composite of two distinct primes$p, q\$, form a cycle --- usually leaving a tail because the cycle tends to close not on the first element of the sequence. The cycle size is called the period of the polynomial. Try...

SEDE returns 145 questions where the tag abstract-algebra was removed‌​, 713 questions for geometry and...
... 70 questions for discrete-mathematics.