  This paper attempts to provide a comprehensive compilation of results, many
new here, involving the invariant totally antisymmetric tensors (Omega tensors)
which define the Lie algebra cohomology cocycles of $su(n)$, and that play an
essential role in the optimal definition of Racah-Casimir operators of $su(n)$.
Since the Omega tensors occur naturally within the algebra of totally
antisymmetrised products of $\lambda$-matrices of $su(n)$, relations within
this algebra are studied in detail, and then employed to provide a powerful
means of deriving important Omega tensor/cocycle identities. The results
include formulas for the squares of all the Omega tensors of $su(n)$. Various
key derivations are given to illustrate the methods employed.
