The ring of arithmetical functions with unitary convolution: General   Truncations
  Let A denote the ring of arithmetical functions with unitary convolution, and let V be a finite subset of the positive integers having the property that for every v in V, all unitary divisors of v lie in V. We study the truncation A_V, an artinian monomial quotient of a polynomial ring in finitely many indeterminates, isomorphic to the ``Artinified'' Stanley-Reisner ring C[\bar{\Delta(V)}] of a certain simplicial complex \Delta(V). 
Jan Snellman