| M.L. Wachs, Whitney homology of semipure shellable posets, J. Algebraic Combin. 9 (1999), 173--207. |
....layer, the subcomplex of all faces of K whosedegreeisatleastr 1 (equivalently, the subcomplex generated by all facets whose dimension is at least r) and K [i] K (i,i) thepure i skeleton, the pure subcomplex generated by all i dimensional faces. The notation K [i] is due to Wachs [Wa]. Other interpretations of K (r,s) then, are that K (r,s) K r ) s) and, if r # s,thatK (r,s) K [r] s) Lemma 2.1. Let L # K be a pair of simplicial complexes. a) If deg L # i 1, then L # K i . b) L i # K i . Proof. a) Let F # L.Becausedeg L ....
....of combinatorics 3 (1996) #R21 7 If i d 1, then K [i 1] and K [i] are Cohen Macaulay. In that case, K [i 1] i) is the skeleton of a Cohen Macaulay complex, and hence Cohen Macaulay. Then, by Corollary 3.2, # i (K) K [i] K [i 1] i) is relative Cohen Macaulay. See [Wa] for another characterization of sequential Cohen Macaulayness, which relies upon Theorem 3.3. 4 Algebraic shifting Algebraic shifting transforms a simplicial complex into a shifted simplicial complex with the same f vector, and also preserves many algebraic properties of the original complex. ....
M. Wachs, "Whitney homology of semipure shellable posets," preprint, 1996.
....layer, the subcomplex of all faces of K whose degree is at least r 1 (equivalently, the subcomplex generated by all facets whose dimension is at least r) and K [i] K (i;i) the pure i skeleton, the pure subcomplex generated by all i dimensional faces. The notation K [i] is due to Wachs [Wa]. Other interpretations of K (r;s) then, are that K (r;s) K r ) s) and, if r s, that K (r;s) K [r] s) Lemma 2.1. Let L K be a pair of simplicial complexes. a) If deg L i 1, then L K i . b) L i K i . Proof. a) Let F 2 L. Because deg L F i ....
....3 (1996) #R21 7 If i d Gamma 1, then K [i 1] and K [i] are Cohen Macaulay. In that case, K [i 1] i) is the skeleton of a Cohen Macaulay complex, and hence Cohen Macaulay. Then, by Corollary 3.2, Omega i (K) K [i] K [i 1] i) is relative Cohen Macaulay. See [Wa] for another characterization of sequential Cohen Macaulayness, which relies upon Theorem 3.3. 4 Algebraic shifting Algebraic shifting transforms a simplicial complex into a shifted simplicial complex with the same f vector, and also preserves many algebraic properties of the original complex. ....
M. Wachs, "Whitney homology of semipure shellable posets," preprint, 1996.
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M.L. Wachs, Whitney homology of semipure shellable posets, J. Algebraic Combin. 9 (1999), 173--207.
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