Accomplishments for week ending 4/9/04  (Don Smith):

  I added propositional proof terms to proverD.pl (focussing+Dyckhoff's)
as well as to prover.pl (the focussing only prover). When a proof is
found, the code checks that the propositional proof terms are valid.
This code works.

   I've added first-order proof terms to both provers but I haven't yet
modified check/3 and syn/2 in proverUtilities.pl to handle first-order
proof terms. That will take some thought.

  I added to prover.pl support for first order formulas (using
'$existential_variable'/2 and '$parameter'/1). For prover.pl I haven't
yet found an intuitionistic formula in which it behaves incorrectly
(though it takes so long on some intutitionistic theorems that I gave up
waiting).

I've added support for first-order formulas to proverD.pl, but there are
still bugs with that code.

I wrote a procedure to do the Godel-Gentzen negative translation,
thereby providing a large set of examples: any first-order theorem can
now be converted into an intuitionistic theorem.  The "Pelletier
formulas" (provided with LeanTap) are first-order theorems, apparently,
and so far prover.pl has successfully proven some of them (slow!!!).
See proverTestCases.pl for the Pelletier formulas.  See
proverUtilities.pl for the negative translation procedure.

I also fixed some bugs in unification.

Made lots of utilities for checking syntax and for converting syntax
from LeanTap format to the more restricted internal format of the
provers.