Re: minimal requirements for Arch document

> A while ago I sent around a picture that contained the various extensions.
> The picture is very complicated to my taste, but it is fairly comprehensive.
> I am attaching it again.

Studying that picture....  

How do you get from (positive?) Horn to Strong (aka classical) Negation
without adding expressive power?  That doesn't seem right.

The blue arrows, in adding new expressive power, are the same as
syntactic sugar?    You can mechanically convert a ruleset backwards
along a blue arrow arc without changing its entailments?    Or am I not
understanding "expressive power"....?

> http://www.w3.org/Submission/2005/SUBM-SWSF-SWSL-20050909/#sec-language
> has a much simpler picture, but not as complete.

Yeah, and I remember thinking at the time that _that_ diagram was
complicated!

[ I want to understand the diagram before replying on other points. ]

   -- Sandro