%0 Journal Article %T A poset view of the major index %A Richard Ehrenborg %A Margaret Readdy %J Mathematics %D 2014 %I arXiv %R 10.1016/j.aam.2014.09.005 %X We introduce the Major MacMahon map and show how this map interacts with the pyramid and bipyramid operators. When the Major MacMahon map is applied to the ab-index of a simplicial poset, it yields the q-analogue of n! times the h-polynomial of the poset. Applying the map to the Boolean algebra gives the distribution of the major index on the symmetric group, a seminal result due to MacMahon. Similarly, when applied to the cross-polytope we obtain the distribution of one of the major indexes on signed permutations due to Reiner. %U http://arxiv.org/abs/1403.4283v2