Re: x*x+1=0

Jan,

In the preface to the American Edition, it says this:

"What we do in Chapter 11 is extend the concept to Boolean algebras, which means that a valid argument may contain not just three classes of statement, but four: true, false, meaningless, and imaginary. The implications of this, in the fields of logic, philosophy, mathematics, and even physics, are profound."

I note that, in the above, imaginary is listed as the fourth class, while meaningless is listed as third. This might be the answer to your question.

--
Regards,
    David Cressey
    www.dcressey.com
"Jan Hidders" <hidders_at_REMOVE.THIS.win.tue.nl> wrote in message
news:94gv99$c38$2_at_news.tue.nl...


> Sounds interesting. Do you know what the 4th boolean value was?

>

> --

>   Jan Hidders