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Source labels openErdős Problems · Measure and integration

Erdős Problem 1038: I

What is the infimum of |{x ∈ ℝ : |f x| < 1}| over all nonconstant monic polynomials f such that all of its roots are real and contained in [-1,1]?

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

Ben Green's Open Problem 35: Lower

Lower bound for c(p)c(p) for 1<p1 < p \le \infty, improving the known value at p=2p = 2 or p=p = \infty.

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

Green's Open Problem 85

Suppose that AA is an open subset of [0,1]2[0, 1]^2 with measure α\alpha. Are there four points in AA determining an axis-parallel rectangle with area >cα2\gt c \alpha^2?

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

Ben Green's Open Problem 35: Upper

Upper bound for c(p)c(p) for 1<p1 < p \le \infty, improving the best-known value at p=p = \infty.

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

Ben Green's Open Problem 94

Let A ⊂ R be a set of positive measure. Does AA contain an affine copy of {1, 1/2, 1/4, . . . }?

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Source labels openErdős Problems · Combinatorics

Erdős Problem 120

Let ARA \subseteq \mathbb{R} be an infinite set. Must there be a set ERE \subseteq \mathbb{R} of positive measure which does not contain any set of the shape aA+ba * A + b for some a,bRa,b \in \mathbb{R} and a0a \neq 0?

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

Erdős Problem 501

For every xRx \in \mathbb{R} let AxRA_x \subset \mathbb{R} be a bounded set with outer measure <1< 1. Must there exist an infinite independent set, that is, some infinite XRX \subseteq \mathbb{R} such that xAyx \notin A_y for all xyXx \neq y \in X?

If the sets AxA_x are closed and have measure <1< 1, then must there exist an independent set of size 33?

Known results: Erdős–Hajnal [ErHa60] proved the existence of arbitrarily large finite independent sets. Hechler [He72] showed the answer is no assuming the continuum hypothesis.

Source checked Jul 26, 20261 pinned Lean statementInspect problem