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May 17, 2023 at 19:15 answer added Peter Taylor timeline score: 1
May 4, 2023 at 12:07 comment added Oleksandr Kulkov Oh I see, thanks for noting! I'm still not sure about the exact interpretation in the given context though...
May 4, 2023 at 12:04 comment added Martin Rubey What I meant to say is that in this form you can interpret it combinatorially, because the coefficients are (essentially) positive and meaningful.
May 4, 2023 at 12:00 comment added Oleksandr Kulkov To the best of my knowledge, the exact value of the LHS is $$\frac{1}{1-xy} \left(y^{n+1} - \left(\frac{y-1}{1-x}\right)^{n+1}\right).$$ You can get it by expanding $$D^{n+1} uv = \sum\limits_{k=1}^{n+1} \binom{n+1}{n} D^{n-k} u D^{k+1} v,$$ but still it's a low-lever symbolic manipulation rather than high-level explanation/interpretation...
May 4, 2023 at 11:53 comment added Martin Rubey If I'm not mistaken, the difference of the two sides is $(y-1)^{n+1} \sum_{m, k} \binom{k+n}{n} y^{m-k} x^m$, which looks quite doable.
May 4, 2023 at 10:49 history asked Oleksandr Kulkov CC BY-SA 4.0