"If the correction channel has a capability equal to Hy(x) (the amount of additional information that must be supplied per second at the receiving point to correct the received message), it is possible to so en
code the correction data as to send it over this channel and correct all but an arbitrarily small fraction of the errors. This is not possible if the
channel capacity is less than Hy(x)." (Shannon and Weaver, 1948, p. 68)
see TENTH theorem of information theory (
Krippendorff)
