  In fact, if one looks closer, all of Schaefer’s satisfiability problems are either NP complete, P complete, \(\oplus\)L complete, NL complete, L complete, or trivial [Allender et al., 2009].  That is the non-trivial problems  in P may be P complete, or complete for one of these three complexity classes within P.  In other words, if we look closer, the NP/P dichotomy phenomenon problem is really a “multi-chotomoy” phenomenon, namely all non-trivial satisfiability problems are complete for one of five well-known complexity classes. 