11 Questions 140 Answers 0 Followers
Questions related from George Stoica
Maybe in general (on metric spaces, etc).
29 October 2023 6,512 10 View
Note. The sequence of polynomials should be the same for all the continuity points; yet the convergence does not have to be uniform of the continuity set. Comment. Looks and sounds like "déjà...
10 October 2023 5,308 11 View
Let a ∈ ℝ and b > 0 be fixed. Find all functions f : [0, ∞) → ℝ satisfying the differential equation f'(x) = -a + b/f(x) for x > 0 and f(0) = 0.
22 January 2021 9,225 13 View
Let 0 < xn ↗ ∞ such that xn+1 - xn → 0 as n → ∞ . Then, for every 0 < c < 1, there exists a subsequence k(n) such that xk(n) - xn → c as n → ∞ . Is the problem true if c ≥ 1?
26 December 2020 3,903 45 View
I have some complicated hints and clues, but I think their solutions should be much simpler.
13 September 2020 6,780 4 View
Let T denote the circle group, that is, the multiplicative group of all complex numbers with absolute value 1. Let f : T → T be a (sequentially) continuous map, and such that f(z2 ) = f2 (z) for...
25 July 2020 2,200 3 View
If it makes easier, assume that f is continuous on [0,∞).
25 July 2020 2,984 3 View
For any given function f : [a, b] → R, there exists a sequence of polynomial functions converging to f at each point where f is continuous. (Note that we did not ask the convergence to be uniform).
25 July 2020 9,109 30 View
If the answer is yes, can one replace log n by another sequence that approaches ∞ faster than log n ?
22 July 2020 7,680 4 View
To avoid trivial solutions, assume that a and b are non-zero real numbers. My feeling is that, for certain values of a and b, there are no such functions.
14 July 2020 4,880 24 View
I was able to prove (only) that neither sequence has a finite limit; probably anyone saw that coming, but it does not answer the question in full. Am I missing something, or is this hard to get?...
04 July 2020 3,889 99 View