Similarity to Cascade-Correlation

[Scott.Fahlman@SEF1.SLISP.CS.CMU.EDU]

    Now as I understand CC it does 
    freeze the weights for each hidden unit once
    asymptotic learning takes place and takes as input to
    a next candidate hidden unit the frozen hidden unit
    output (ie hyperplane decision or discriminant function).

Right.  The frozen hidden unit becomes available both for forming an output
and as an input to subsequent hidden units.

An aside: Instead of "freezing", I've decided to call this "tenure" from now
on.  When a candidate unit becomes tenured, it no longer has to learn any
new behavior, and from that point on other units will pay attention to what
it says.

    Consequently, CC does not "...keep all of the training 
    data together and <keeps> retraining the output units (weights?) as it 
    incrementlly adds hidden units".

How does this follow from the above?
    
    As to higher-order hidden units... I guess i see what you mean, however,
    don't units below simply send a decision concerning the subset
    of data which they have correctly classified?

It's not just a decision.  The unit's output can assume any value in its
continuous range.  Some hidden units develop big weights and tend to act
like sharp-threshold units, while others do not.

    Consequently,
    units above see the usual input features and a 
    newly learned hidden unit feature indicating that a some subset 
    of the input vectors are on one side of its decision surface? right?

Right, modulo the comment above.

    Consequently the next hidden unit in the "cascade" can learn
    to ignore that subset of the input space and concentrate on
    other parts of the input space that requires yet another hyperplane?  
    It seems as tho this would produce a branching tree of discriminantS
    similar to cart.

No, this doesn't follow at all.  Typically there are still errors on both
sides of the unit just created, so the next unit doesn't ignore either
"branch".  It produces some new cut that typically subdivides all (or many)
of the regions created so far.  Again, I suggest you look at the diagrams
in the tech report to see the kinds of "cuts" are actually created.
    
    n'est pas?

Only eagles nest in passes.  Lesser birds hide among the branches of
decision trees.  :-)

-- Scott