[SCL] Update to SCL-related work

[Tanel Tammet]

Hi,

During the last few days I have significantly
updated the ECL language (SCL branch).

Have a look at
http://www.ttu.ee/it/elm/ecl.html

Main changes:

   - Principal changes in the data type
     (numbers, strings, etc)  handling.
   - Chapters for two concrete syntaxes
   - Adoption of the KIF-like syntax in
     most examples and axioms
   - Restructuring the chapters

As said before, it would be great if we
could ever merge SCL and ECL.

 From my viewpoint (other people might have
very different considerations) the
following things should be done with
the SCL draft Pat has been writing:

- Clarification of the basic semantics.

   As it stands now, I cannot really understand
   all the details there, and this leaves
   two main possibilities:

    - perhaps the SCL semantics is
      objectively much more complex
      than FOL semantics
    - perhaps it is written down in
      a far too complex way.

  IMHO: an easy-to-understand FOL-based
  semantics is crucial for a language
  like SCL.

- Equality confusion solved. As it stands
   now, many of the complexities in the
   semantics seem to be motivated by the
   desire to fight the Horrocks sentences,
   which is purely a problem with equality
   axiomatisation. The current SCL
   approach seems to be the requirement
   to declare some predicates and functions
   in a special header, which I think is
   a very bad idea (unless the declaration
   is optional, in which case it is fine).

- Annotations (at least comments) added.

- Crucial data types fully axiomatised,
   at least numbers, strings and lists.


Regards,
              Tanel Tammet