Actually, I've sort of hacked something together:
(defun rat-power (f var)
(setf f ($rat f var))
(let* ((top (if (consp (cadr f)) (cadr f) (list (cadr f))))
(bottom (cddr f))
(symlists (loop for x on (car f) until (listp (car x))
finally (return x)))
(symb (nth (position var (first symlists)) (second symlists))))
(simplifya
`((mplus)
,(if (eq (car top) symb) (cadr top) 0)
((mtimes) -1 ,(if (eq (car bottom) symb) (cadr bottom) 0)))
nil)))
But eugh, so hopefully there's a better way!
Another unrelated question: Is there a way to receive ones own emails
to the list. I'm reasonably sure I've asked the web interface for it,
but can only get it to give me post acknowledgements. Thus this email
isn't going to be in the right thread, sorry.
Rupert
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