This thread is about umbral calculus and and exercise about Appell Sequences. I provide first the question, then the definition, then a first attempt at solving the question, then I ask as an optional question if the first method could work, then I propose a second method (in which I ask an opti...
The tag feature of Math Stack Exchange seems to be a nice feature but I don't understand why some are allowed and some aren't. For the example of umbral calculus, I tried the "umbral" tag. I can understand that the Sheffer sequences or Appell sequences are removed because probably to specific. Is...
I am reading the book The Mathematics of Diffusion by J. Crank (cf. Crank_1975_Diffusion) and, at pages 13-16, I could not understand the relation between $h$ and $l$. I am beginner yet and on my short thought they do not have any relation, I mean, I imagine the column between $0$ and $l$. Where ...
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