I made my Hilbert axiomatic geometry code more readable, but code that
ran in 1:07 minutes now runs in 2:15 minutes.  I sure enjoyed myself!
Perhaps this is an interface issue of the sort Mark & Felix raised.

I'd like to be able to write != or <> to mean "not equal" and have it
work fine, so that e.g. miz3 would know that ~(x = y) is the same as x
<> y, and if my thesis is
(x = y) \/ alpha
I could prove it by first making the assumption
x <> y
and then proving alpha.   I tried this for IN, defining NOTIN by 

let NOTIN = new_definition
  `!a:A l:A->bool. a NOTIN l  <=> ~(a IN l)`;;

I had to make massive changes to get away with this, and it was fun,
as I improved some sub-optimal old proofs, but I don't like this:

let Interval2sides2aLineHelp_THM = thm `;
  let A B C X be point;
  let l be point_set;
  assume ¬(A = B) ∧ ¬(A = C) ∧ ¬(A = X) ∧ ¬(B = C) ∧ ¬(B = X) ∧ ¬(C = X)     
[H1];
  assume Line l ∧ A ∈ l ∧ B ∈ l ∧ C ∈ l ∧ X ∈ l     [H2];
  assume B ∈ open (A,C)     [H3];                        
  thus X ∉ open (A,B) ∨ X ∉ open (B,C) 

  proof
    assume ¬(X ∉ open (A,B));
    X ∈ open (A,B)     [X_AB] by -, ∉;
    Collinear X B C     [XBCcol] by H2, Collinear_DEF;
    ordered A X B C     [AXBC] by X_AB, H3, TransitivityBetweennessVariant_THM;
    B ∈ open (X,C)     [B_XC] by AXBC, Ordered_DEF;
    X ∉ open (C,B)     by H1, XBCcol, B_XC, B3', ∉;
  qed     by -, B1', ∉`;;

It would be nice to replace the first two lines of my proof with 
    assume X ∈ open (A,B)     [X_AB];

As another interface issue, I find my concrete syntax here, which
Emacs pre-processes (turning ∉ to NOTIN), to be improve readability.

Anyway, I'm happy, I've basically formalized the first 6 sections of
my paper, and so I only have one left to formalize, the hardest, which
treats Hartshorne's book, and I'm over 2700 lines of code!
http://www.math.northwestern.edu/~richter/RichterHOL-LightMiz3HilbertAxiomGeometry.tar.gz
-- 
Best,
Bill 

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