I am looking for:
- Michael O. Rabin, "Degree of difficulty of computing a function, and a partial ordering of recursive sets", Hebrew University, Jerusalem, 1960
“We attempt to measure the amount of work inherent in the task of computing a given computable (recursive) function. A notion of degree of difficulty of computing is introduced and studied. The notion is invariant in the sense that it is independent of the idealized computers (Turing Machines) used for computing the functions in question. Applications are made to the classification of solvable decision problems (recursive sets) according to relative difficulty.”
I couldn't find a copy online or at our library.