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Open-problem statements, with their sources attached.

Each statement record keeps the mathematical question, a dated status source, accessible references, and any pinned Lean formulation separate from proof verification.

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Source labels openGreen's Open Problems · Combinatorics

Ben Green's Open Problem 14

W(3,38)>1378W(3, 38) > 1378 from [AKS14, Table 3].

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

Erdős Problem 354: Ii

Let α,βR>0\alpha,\beta\in \mathbb{R}_{>0} such that α/β\alpha/\beta is irrational. Is

\{ \lfloor \beta\rfloor,\lfloor \gamma\beta\rfloor,\lfloor \gamma^2\beta\rfloor,\ldots\}$$ complete?
Source checked Jul 26, 20261 pinned Lean statementInspect problem
Source labels openGreen's Open Problems · Combinatorics

Ben Green's Open Problem 14

W(3,39)>1418W(3, 39) > 1418 from [AKS14, Table 3].

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

Erdős Problem 357: I

Let f(n)f(n) be the maximal kk such that there exist integers 1a1<<akn1 \le a_1 < \dotsc < a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. Is f(n)=o(n)f(n)=o(n)?

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

Green's Open Problem 15

Does there exist a Lipschitz function f:NZf : \mathbb{N} \to \mathbb{Z} whose graph Γ={(n,f(n)):nN}Z2\Gamma = \{(n, f(n)) : n \in \mathbb{N}\} \subseteq \mathbb{Z}^2 is free of 3-term progressions?

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

Erdős Problem 357: Big O Version

Let f(n)f(n) be the maximal kk such that there exist integers 1a1<<akn1 \le a_1 < \dotsc < a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. How does f(n)f(n) grow? Can we find a (good) explicit function gg such that g=O(f)g = O(f) ?

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

Ben Green's Open Problem 16

What is the largest subset of [N][N] with no solution to x+3y=2z+2wx + 3y = 2z + 2w in distinct integers x,y,z,wx, y, z, w?

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

Erdős Problem 357: Big O Version Symm

Let f(n)f(n) be the maximal kk such that there exist integers 1a1<<akn1 \le a_1 < \dotsc < a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. How does f(n)f(n) grow? Can we find a (good) explicit function gg such that f=O(g)f = O(g) ?

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

Ben Green's Open Problem 16

From [Ruzsa] f(N)N1/2f(N) \gg N^{1/2}.

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

Erdős Problem 357: Big Theta Version

Let f(n)f(n) be the maximal kk such that there exist integers 1a1<<akn1 \le a_1 < \dotsc < a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. How does f(n)f(n) grow? Can we find a (good) explicit function gg such that f=Θ(g)f = \Theta(g) ?

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

Ben Green's Open Problem 16

From [Schoen and Sisask] f(N)Nec(logN)1/7f(N) \ll N \cdot e^{-c(\log N)^{1/7}}.

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

Erdős Problem 357: Little O Version

Let f(n)f(n) be the maximal kk such that there exist integers 1a1<<akn1 \le a_1 < \dotsc < a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. How does f(n)f(n) grow? Can we find a (good) explicit function gg such that g=o(f)g = o(f) ?

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

Ben Green's Open Problem 16

f(N)Nec(logN)1/7f(N) \gg N \cdot e^{-c(\log N)^{1/7}}.

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

Erdős Problem 357: Little O Version Symm

Let f(n)f(n) be the maximal kk such that there exist integers 1a1<<akn1 \le a_1 < \dotsc < a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. How does f(n)f(n) grow? Can we find a (good) explicit function gg such that f=o(g)f = o(g) ?

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

Ben Green's Open Problem 16

From [Yufei Zhao]: Is there a subset of {1,,N}\{1, \ldots, N\} of size N1/3o(1)N^{1/3 - o(1)} with no nontrivial solutions to x+2y+3z=x+2y+3zx + 2y + 3z = x' + 2y' + 3z'?

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

Erdős Problem 357: Infinite Set Density

Suppose AA is an infinite set such that all finite sums of consecutive terms of AA are distinct. Then it is conjectured that AA has density 0.

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

Ben Green's Open Problem 18

Suppose that GG is a finite group, and let AG×GA \subset G \times G be a subset of density α\alpha. Is it true that there are αG3\gg_\alpha |G|^3 triples x,y,gx, y, g such that (x,y),(gx,y),(x,gy)(x, y), (gx, y), (x, gy) all lie in AA?

Note: A is taken as α\alpha-dense, i.e. AαG2|A| \ge \alpha |G|^2 [Au16, Question 2]

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

Erdős Problem 357: Infinite Set Sum

Suppose AA is an infinite set such that all finite sums of consecutive terms of AA are distinct. Then it is conjectured that the sum k1ak\sum_k \frac{1}{a_k} converges.

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

Ben Green's Open Problem 19: Lower

[Ma21] showed that 3.13C3.13 \leq C.

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

Erdős Problem 357: Hegyvari

Let g(n)g(n) be the maximal kk such that there exist integers 1a1,,akn1 \le a_1, \dotsc, a_k \le n such that all sums of the shape uivai\sum_{u \le i \le v} a_i are distinct. It is known that (13+o(1))ng(n)(23+o(1))n.\left(\frac 1 3 + o(1) \right)n \leq g(n) \leq \left(\frac 2 3 + o(1) \right)n.

Source checked Jul 26, 20261 pinned Lean statementInspect problem