“Indeed, if general recursive function is the formal equivalent of effective calculability, its formulation may play a role in the history of combinatory mathematics second only to that of the formulation of the concept of natural number.” —E.L. Post, addressing the American Mathematical Society, in 1944.
Prepare to read”
FORMAL REDUCTIONS OF THE GENERAL COMBINATORIAL DECISION PROBLEM.* By EMIL L. POST.
RECURSIVELY ENUMERABLE SETS OF POSITIVE INTEGERS AND THEIR DECISION PROBLEMS By EMILL.POST”