[26] A complexity class which is likely to be properly contained in \(\textbf{EXP}\) but which still contains many apparently infeasible problems which arise in computational practice is \(\textbf{PSPACE}\). e. a statement of the form \(Q_1 x_i \ldots Q_n x_n\psi\) where \(Q_i = \exists\) or \(\forall\) and \(\psi\) is a formula of propositional logic containing the propositional variables \(x_1,\ldots,x_n\) which are treated as bound by these quantifiers. g. \(\forall x_1 \exists x_2 (x_1 \vee