erdős #209
Let be a finite collection of non-parallel lines in such that there are no points where at least four lines from meet. Must there exist a 'Gallai triangle' (or 'ordinary triangle'): three lines from which intersect in three points, and each of these intersection points only intersects two lines from ?
Worked, still open.
geometry · solved · 0 attempts
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vela registry pull vfr_37aec80d874a0239vela reproduce examples/erdos-problems