An oracle separating (+)P from PP/sup PH/
F. Green · 2002
The existence of an oracle A such that (+)P/sup A/ is not contained in PP/sup PHA/ is proved. This separation follows in a straightforward manner from a circuit complexity result, which is also proved: to compute the parity of n inputs, any constant depth circuit consisting of a single threshold gate on top of ANDs and ORs requires exponential size in n.>