(1) Department of Mathematics, Faculty of Education, Saga University, Saga 840, Japan;(2) Department of Mathematics, Graduate School of Science, Osaka University, Toyonaka Osaka, 560, Japan
Abstract:
A technique of minimal free resolutions of Stanley—Reisner rings enables us to show the following two results: (1) The 1-skeleton of a simplicial (d–1)-sphere is d-connected, which was first proved by Barnette; (2) The comparability graph of a non-planar distributive lattice of rank d–1 is d-connected.