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Michael Hardy
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Is there a set of point $S \subset \mathbb R^2$ such that $|\{C: C \text{ is unit circle boundary }, |C \cap S| = 10\}| > |S|$

There are some blue points and red points on the plane such that in the boundary of every unit circle centered at one blue point there are exactly 10 red point. Can the number of blue points strictly greater than the number of red points ?

This is a problem I found a very long time ago with any solution the only hint I found is this problem will use probabilistic method somewhere

I figured out that if we change exactly 10 to at least 10, the answer is yes, it is because we can chessboard coloring a large grid and scale it down by a factor of $1/ \sqrt{N}$ where $N$ satisfy that the solution $x^2+y^2 = N$ has at least 10 positive integer solution.

Translating the problem into a set-intersecting problem will not work here, there exist a large number $n$ and a family of set $\mathcal F$ with $|\mathcal F| = O(n^2)$ such that $|C| = 10$ and $C \subset \{1,2,\ldots,n\}$ for every $C \in \mathcal F$ and $|C_i \cap C_j| < 2 $ for all $C_i, C_j \in \mathcal F, C_i \not = C_j$