of_sort_derivation: weaken bypasses derivation for identical sort -- accomodate proof terms by krauss/schropp, for example;
header {* Main HOL *}
theory Main
imports Plain Predicate_Compile Nitpick
begin
text {*
Classical Higher-order Logic -- only ``Main'', excluding real and
complex numbers etc.
*}
text {* See further \cite{Nipkow-et-al:2002:tutorial} *}
end