# On the PCT--Theorem in the Theory of Local Observables

December 11, 2000

We review the PCT-theorem and problems connected with its demonstration. We
add a new proof of the PCT-theorem in the theory of local observables which is
similar to that one of Jost in Wightman quantum field theory. We also look at
consequences in case the PCT-symmetry is given on the algebraic level. At the
end we present some examples which answer general questions and throw some
light on open problems.

Keywords:

*none*