FUNCTIONAL SMARANDACHE ITERATIONS 1) Functional Smarandache Iteration of First Kind: Let f: A ---> A be a function, such that f(x) <= x for all x, and min {f(x), x belongs to A} > = m0, different from negative infinity. Let f have p >= 1 fix points: m0 <= x1 < x2 < ... < xp. [The point x is called fix if f(x) = x.] Then SI1 (x) = the smallest number of iterations k such that f f(f(...f(x)...)) = constant. iterated k times Example: Let n > 1 be an integer, and d(n) be the number of positive divisors of n, d: N ---> N. Then SI1 (n) is the smallest number of iterations k d such that d(d(...d(n)...)) = 2; iterated k times because d(n) < n for n > 2, and the fix points of the function d are 1 and 2. Thus SI1 (6) = 3, because d(d(d(6))) = d(d(4)) = d(3) = 2 = constant. d SI1 (5) = 1, because d(5) = 2. d 2) Functional Smarandache Iteration of Second Kind: Let g: A ---> A be a function, such that g(x) > x for all x, and let b > x. Then: SI2 (x, b) = the smallest number of iterations k such that g g(g(...g(x)...)) >= b. iterated k times Example: Let n > 1 be an integer, and sigma(n) be the sum of positive divisors of n (1 and n included), sigma: N ---> N. Then SI2 (n, b) is the smallest number of iterations k such that sigma sigma(sigma(...sigma(n)...)) >= b, iterated k times because sigma(n) > n for n > 1. Thus SI2 (4, 11) = 3, because sigma(sigma(sigma(4))) = sigma sigma(sigma(7)) = sigma(8) = 15 >= 11. 3) Functional Smarandache Iteration of Third Kind: Let h: A ---> A be a function, such that h(x) < x for all x, and let b < x. Then: SI3 (x, b) = the smallest number of iterations k such that h h(h(...h(x)...)) <= b. iterated k times Example: Let n be an integer and gd(n) be the greatest divisor of n, less than n, gd: N* ---> N*. Then gd(n) < n for n > 1. SI3 (60, 3) = 4, because gd(gd(gd(gd(60)))) = gd(gd(gd(30))) = gd gd(gd(15)) = gd(5) = 1 <= 3. References: [1] Ibstedt, H., "Smarandache Iterations of First and Second Kinds", , Vol. 17, No. 4, Issue 106, 1996, p. 680. [2] Ibstedt, H., "Surfing on the Ocean of Numbers - A Few Smarandache Notions and Similar Topics", Erhus University Press, Vail, 1997; pp. 52-58. [3] Smarandache, F., "Unsolved Problem: 52", , Xiquan Publishing House, Phoenix, 1993.