During the International Congress of Mathematicians in Paris in 1900 David Hilbert (1862–1943), one of the leading mathematicians of the last century, proposed a list of problems for following generations to ponder [8, p. 290–329] [9]. On the list was whether the axioms of arithmetic are consistent, a question which would have profound consequences for the foundations of mathematics. Continuing in this direction, in 1928 Hilbert proposed the decision problem (das Entscheidungsproblem) [10, 11, 12], which asked whether there was a standard procedure that can be applied to decide whether a given mathematical statement is true. Both Alonzo Church (1903–1995) [2, 3] and Alan Turing (1912–1954) [13] published papers in 1936 demonstrating that the decision problem has no solution, although it is the algorithmic character of Turing’s paper “On Computable Numbers, with an Application to the Entscheidungsproblem” [13] that forms the basis for the modern programmable computer. Today his construction is known as a Turing machine. Let’s first study a few excerpts from Turing’s original paper [13, p. 231–234], and then design a few machines to perform certain tasks.
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