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Source labels openGreen's Open Problems · Probability

Green's Open Problem 28

Suppose that X,YX, Y are two finitely-supported independent random variables taking integer values, and such that X+YX + Y is uniformly distributed on its range. Are XX and YY themselves uniformly distributed on their ranges?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openGreen's Open Problems · Functional analysis

Ben Green's Open Problem 54

Let KRnK \subset \mathbb{R}^n be a balanced compact set (that is, λKK\lambda K \subseteq K whenever λ1|\lambda| \leq 1) and suppose that the normalised Gaussian measure γn(K)0.99\gamma_n(K) \geq 0.99. Does 10K10K contain a compact convex set CC with γn(C)0.01\gamma_n(C) \geq 0.01?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Field theory and polynomials

Erdős Problem 522

Let f(z)=0knϵkzkf(z)=\sum_{0\leq k\leq n} \epsilon_k z^k be a random polynomial, where ϵk{1,1}\epsilon_k\in \{-1,1\} independently uniformly at random for 0kn0\leq k\leq n.

Is it true that, if RnR_n is the number of roots of f(z)f(z) in {zC:z1}\{ z\in \mathbb{C} : \lvert z\rvert \leq 1\}, then

Rnn/21 \frac{R_n}{n/2}\to 1

almost surely?

There is some ambiguity as to whether the intended coefficient set is {1,1}\{-1, 1\} or {0,1}\{0, 1\}, see erdos_522.variants.zero_one for the alternate version.

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Field theory and polynomials

Erdős Problem 522: Zero One

Let f(z)=0knϵkzkf(z)=\sum_{0\leq k\leq n} \epsilon_k z^k be a random polynomial, where ϵk{0,1}\epsilon_k\in \{0,1\} independently uniformly at random for 0kn0\leq k\leq n.

Is it true that, if RnR_n is the number of roots of f(z)f(z) in {zC:z1}\{ z\in \mathbb{C} : \lvert z\rvert \leq 1\}, then

Rnn/21 \frac{R_n}{n/2}\to 1

almost surely?

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openGreen's Open Problems · Combinatorics

Green's Open Problem 39

If AZ/pZA \subset \mathbb{Z}/p\mathbb{Z} is random, A=p|A| = \sqrt{p}, can we almost surely cover Z/pZ\mathbb{Z}/p\mathbb{Z} with 100p100\sqrt{p} translates of AA? [Gr24]

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openGreen's Open Problems · Combinatorics

Green's Open Problem 39: Variant 101

"I do not know how to answer this even with 100 replaced by 1.01." [Gr24]"

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Source labels openGreen's Open Problems · Combinatorics

Green's Open Problem 39: Variant Theta

Similar questions are interesting with p\sqrt{p} replaced by pθp^\theta for any θ1/2\theta \le 1/2. [Gr24]

NOTE: using CpθC p^\theta translates as stated makes the conjecture trivially false by the pigeonhole principle. Indeed for a set of size pθp^\theta, we cover at most Cp2θC p^{2\theta} elements, which is strictly less than pp for θ<1/2\theta < 1/2. We interpret the question as asking whether O(p1θ)O(p^{1-\theta}) translates suffice. This generalizes the main conjecture where p=p11/2\sqrt{p} = p^{1-1/2}.

Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openErdős Problems · Number theory

Erdős Problem 520

Let ff be a Rademacher multiplicative function. Does there exist some constant c>0c > 0 such that, almost surely,

lim supNmNf(m)NloglogN=c? \limsup_{N \to \infty} \frac{\sum_{m \leq N} f(m)}{\sqrt{N \log \log N}} = c?
Source checked Jul 26, 20261 pinned Lean statementInspect problem