let H be CTL-formula; :: thesis: ( H is ExistNext implies ( not H is atomic & not H is conjunctive & not H is negative & not H is ExistGlobal & not H is ExistUntill ) )
assume H is ExistNext ; :: thesis: ( not H is atomic & not H is conjunctive & not H is negative & not H is ExistGlobal & not H is ExistUntill )
then H . 1 = 2 by Lm5;
hence ( not H is atomic & not H is conjunctive & not H is negative & not H is ExistGlobal & not H is ExistUntill ) by Lm3, Lm4, Lm6, Lm7, Lm8; :: thesis: verum