 By Constantin Meghea

ISBN-10: 3540055797

ISBN-13: 9783540055792

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This text discusses a few equipment of describing and relating mathematical items and of constantly and unambiguously signaling the logical constitution of mathematical arguments.

Extra info for Compactification des Espaces Harmoniques

Example text

If n ≥ 2m, note that sn = sm sn−m − 5m 7m sn−2m , so gcd(sm , sn ) = gcd(sm , sn−2m ).. Similarly, if m < n < 2m, we have gcd(sm , sn ) = gcd(sm , s2m−n ). Thus by the Euclidean algorithm, we conclude that if m + n is even, then gcd(sm , sn ) = gcd(s1 , s1 ) = 12, and if m+n is odd, then gcd(sm , sn ) = gcd(s0 , s1 ) = 2. 3. Let x > 1 be a real number which is not an integer. For n = 1, 2, 3, . , let an = xn+1 − x xn . Prove that the sequence {an } is not periodic. Solution: Assume, on the contrary, that there exists p > 0 such that ap+n = an for every n.

Bt . Find the first position in which they differ; without loss of generality, assume this position is k and that ak > bk . Then m≤ bk k + bk − 1 bk − k + 1 + ··· + k−1 1 < bk + 1 k ≤ m, a contradiction. To show existence, apply the greedy algorithm: find the largest ak such that akk ≤ m, and apply the same algorithm with m and k replaced by m − akk and k − 1. We need only make sure that the sequence obtained is indeed decreasing, but this follows because by ak assumption, m < akm+1 , and so m − akk < k−1 .

Thus f (z) = 0 for all z ∈ C. 2. Find the greatest positive integer n for which there exist n nonnegative integers x1 , x2 , . . , xn , not all zero, such that for any sequence 3 1 , 2 , . . , n of elements of {−1, 0, 1}, not all zero, n does not divide 1 x1 + 2 x2 + . . + n xn . Solution: The statement holds for n = 9 by choosing 1, 2, 22 , . . , 28 , since in that case | 1 + ··· + 8 92 | ≤ 1 + 2 + · · · + 28 < 93 . However, if n = 10, then 210 > 103 , so by the pigeonhole principle, there are two subsets A and B of {x1 , .