Saya mau tau "Formal" cumulants dari Cumulant. Jelaskan dalam bahasa sunda

More generally, the cumulants of a sequence { mn : n = 1, 2, 3, ... }, not necessarily the moments of any probability distribution, are given by

where the values of κn for n = 1, 2, 3, ... are found "formally", i.e., by algebra alone, in disregard of questions of whether any series converges.  All of the difficulties of the "problem of cumulants" are absent when one works "formally".  The simplest example is that the second cumulant of a probability distribution must always be nonnegative, and is zero only if all of the higher cumulants are zero.  "Formal" cumulants are subject to no such constraints.