I've been working on extending the capabilities of the solver and have
something that is passing the tests as well as being able to make
general u-substitutions to turn expressions into polynomials
(including trig expressions) and expressions with radicals. I am stuck
right now trying to think of how to do a symmetric test for something
like 2**x-5**x which has a trivial-like solution of x=0 which sets
both terms to 1 (not 0) and they cancel. Does anyone have any ideas of
how to recognize when such an attempt might succeed...and when if
might fail?

e.g. Given x + (1-x**2)**(1/2) if we try to see if there are any
values of x that set both terms to a cancelling constant, we proceed
as follows:

  we need the value of x that sets x=c and (1-x**2)**(1/2)=-c but
solving the second term for x gives x=(1-c**2)**(1/2) and if we equate
that with the negative of the x obtained from x=c we are led back to
where we started:

   c+(1-c**2)**(1/2) = 0

==> infinite solving loop.

Does anyone understand what I am trying to do and have any suggestions
on how to accompllish it? Is there a way that this could be extended
to more than 1 term, perhaps through pattern matching?

/c
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