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Apr 30, 2020 at 18:34 history edited Matt Samuel CC BY-SA 4.0
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Apr 30, 2020 at 14:48 comment added Bipolar Minds @SamHopkins thanks for the reference, this exactly the direction I'm aiming for
Apr 30, 2020 at 14:44 comment added Matt Samuel @BipolarMinds Not sure if it will be useful, but I combinatorially described a recurrence for $\frac{\binom{n+1}2!}{|R(w_0(n))|}$.
Apr 30, 2020 at 14:42 history edited Matt Samuel CC BY-SA 4.0
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Apr 30, 2020 at 14:39 comment added Sam Hopkins @BipolarMinds: it sounds like you might be interested in higher Bruhat orders in the sense of Manin--Schechtman/Ziegler (doi.org/10.1016/0040-9383(93)90019-R). In that paper Ziegler says that, beyond the case covered by Stanley's work, little is known in terms of enumeration. But of course that paper is 30 years old so perhaps more is known now.
Apr 30, 2020 at 14:26 history edited Matt Samuel CC BY-SA 4.0
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Apr 30, 2020 at 14:22 comment added Bipolar Minds Yes, I actually did the same thing at first :)
Apr 30, 2020 at 14:21 comment added Matt Samuel @BipolarMinds That's fair, but are you sure it's not always a natural number?
Apr 30, 2020 at 14:16 comment added Bipolar Minds Well yes, fair enough :) My problem with this is that the quotient is not always a natural number, so it doesn't count anything. The recurrence relation should come from a bijection on sets, as for example $S_n= S_{n-1}\times [n]$ gives $n! =n(n-1)!$. In some sense, it should be a higher analogue of this identity, but I don't expect it to be easy. Sorry for my imprecise formulation of the question.
Apr 30, 2020 at 13:04 history edited Matt Samuel CC BY-SA 4.0
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Apr 27, 2020 at 18:36 comment added Bipolar Minds I found it in a paper of Richard Stanley
Apr 27, 2020 at 18:29 comment added Matt Samuel @BipolarMinds The formula is well known, for example it's in Combinatorics of Coxeter groups by Bjorner and Brenti, though I'm not sure of the original source.
Apr 27, 2020 at 18:26 comment added Bipolar Minds Thx! I actually forgot to write that I mean recurrence relation in $n$ but now that there is a closed formula, all the better
Apr 27, 2020 at 18:23 vote accept Bipolar Minds
Apr 30, 2020 at 10:20
Apr 27, 2020 at 18:18 history answered Matt Samuel CC BY-SA 4.0