Comments by "robheusd" (@robheusd) on "The Most Difficult Program to Compute? - Computerphile" video.

  1. /* Is there a pattern of Ackermann functions ?? */ int ack0() { return 1; } int ack1(int n) { if (n == 0) return ack0(); else return ack1(n - 1); } int ack2(int m, int n) { if (m == 0) return ack1(n) + ack0(); else if (n == 0) return ack2(m - 1, ack0()); else return ack2(m - 1, ack2(m, n - 1)); } // Then ack3 would be something like this ?? int ack3(int k, int l, int m) { if (k == 0) return ack2(l, ack1(m)) + ack1(m) + ack0(); else (if l == 0) return ack2(k - 1, ack2(1, m)); else if (m == 0) return ack3(k - 1, ack2(l, m - 1)), ack0()); else return ack3(k - 1, ack3(k, ack2(l, m) , ack2(l, m - 1)) - 1, ack2(l - 1, ack2(l, m) - 1)); } ...... int ackn(int n, int x[n]) { // ???? Could we even express the function in C ??? }
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