Editing Möbius function (section)

===Incidence algebras===
In [[combinatorics]], every locally finite [[partially ordered set]] (poset) is assigned an [[incidence algebra]]. One distinguished member of this algebra is that poset's "Möbius function". The classical Möbius function treated in this article is essentially equal to the Möbius function of the set of all positive integers partially ordered by [[divisor|divisibility]]. See the article on [[incidence algebra]]s for the precise definition and several examples of these general Möbius functions.