We construct for each
nn an Eulerian partially ordered set
TnT_n of
rank
n+1n+1 whose
cece-index provides a non-commutative generalization of
the
nnth Tchebyshev polynomial. We show that the order complex of each
TnT_n
is shellable, homeomorphic to a sphere, and that its face numbers minimize the
expression
max|x| £ 1 |åj=0n (fj-1/fn-1)·2-j·(x-1)j|\max_{|x|\leq 1} |\sum_{j=0}^n (f_{j-1}/f_{n-1})\cdot
2^{-j}\cdot (x-1)^j|
among the
ff-vectors of all
(n-1)(n-1)-dimensional simplicial
complexes. The duals of the posets constructed have a recursive
structure similar to face lattices of simplices or cubes, offering the
study of a new special class of Eulerian partially ordered sets to test
the validity of Stanley

s conjecture on the non-negativity of the
cdcd-index of all Gorenstein
*^* posets.