We next define a -counterpart of * and * and look into some of its closure properties.
18.104.22.168 Definition. (Semi-computable Relations) A relation P() is called semi-computable or semi-recursive iff for some f , we have, for all n,
The set of all semi-computable relations is denoted by *.
If in (1) above, then we say that “a” is a semi-computable index ...