I have been studying Shannon's proof of Vernams (1917) unbreakable cipher. Can His proof be applied to positional ciphers?
Can his proof be applied to positional ciphers.
Shannon's proof requires that there be at least as many possible keys as possible plaintexts; unless your positional cipher has that property, then no, it cannot.
(I'm not sure what you're referring to as a 'position cipher' - would that be a transposition cipher?)