Inclusion-exclusion: Which terms cancel?
The author continues his study of the inclusion-exclusion principle (see his paper [Arch. Math. 72, No. 4, 298-303 (1999; Zbl 0934.05011)]), considering cancellations. The terms are regarded as nodes of a rooted tree (the Hasse diagram for the corresponding partial order), and each set of cancelling terms is identified with a subtree of this tree.
scientific article; zbMATH DE number 1462962