Move Negation Inward (Perlis85)

Perlis85 proposes that a quoted sentence is true if and only if a rewriten version of the sentence, with negation moved inside any quotation operators, is true. This is what KIF94 used, but was abandoned in KIF98 as being unnecessarily complex for their intended applications.

I'm unclear about whether the rewrite is always possible; I suspect it is not possible using some styles of quotation, so this truth predicate would really be 3-valued (true, false, bad). It seems reasonable to me that isTrue("this sentence is false") ==> bad.