for r being non negative Real
for n being non zero Element of NAT
for o being Point of (TOP-REAL n)
for x being Point of (Tdisk (o,r))
for f being Function of (Tdisk (o,r)),(Tdisk (o,r)) st not x is_a_fixpoint_of f & x is Point of (Tcircle (o,r)) holds
HC (x,f) = x