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Published online by Cambridge University Press: 12 March 2014
In Smullyan [1], where recursive enumerability is defined in terms of elementary dyadic arithmetics (dyadic EA's), it is shown that for any number n, the parallel definition in terms of n-adic EA′s is equivalent. This proof at one stage uses the deep result of Godei that plus and times form a sub-basis for the recursively enumerable attributes (sets and relations)2. The aim of this note is to prove this equivalence in more pedestrian fashion.
I am indebted to the referee, who suggested using a construction from Smullyan [2] that made my proof shorter and more elegant.