One version of this statement made use of lambda definability, which is described as a function that can be calculated by a process of repeated substitution, and another was originally developed while attempting to prove that a posed problem for the predicate calculus was unsolvable. Copeland and Proudfoot wrote a controversial Scientific American article about it, in which they suggest the creation of an oracle.  It says that the halting problem is undecidable, and though it may not be able to be proved, every realistic model discovered has proven to be equivalent. FT
One version of this statement made use of lambda definability, which is described as a function that can be calculated by a process of repeated substitution, and another was originally developed while attempting to prove that a posed problem for the predicate calculus was unsolvable. Copeland and Proudfoot wrote a controversial Scientific American article about it, in which they suggest the creation of an oracle.  It says that the halting problem is undecidable, and though it may not be able to be proved, every realistic model discovered has proven to be equivalent. FTP name this thesis that says any effective computation can be translated into an equivalent computation by one of its namesake's eponymous machines.
One version of this statement made use of lambda definability, which is described as a function that can be calculated by a process of repeated substitution, and another was originally developed while attempting to prove that a posed problem for the predicate calculus was unsolvable.
Church-Turing Thesis [accept in either order; prompt on only a single name]