(= (rev-w $c) (/ $c (- 1 $c)))

(= (corrected-revise (stv $f1 $c1) (stv $f2 $c2))
  (let* (($w1 (rev-w $c1))
         ($w2 (rev-w $c2))
         ($ws (+ $w1 $w2))
         ($fr (/ (+ (* $w1 $f1) (* $w2 $f2)) $ws))
         ($cr (/ $ws (+ $ws 1)))
         ($wc (* (/ $cr (- 1 $cr)) 0.49))
         ($cc (/ $wc (+ $wc 1))))
    (stv $fr $cc)))

!(corrected-revise (stv 0.7 0.5) (stv 0.6 0.4))
!(corrected-revise (stv 0.9 0.8) (stv 0.3 0.6))
!(corrected-revise (stv 0.8 0.9) (stv 0.8 0.9))