Equiangular lines with a fixed angle

نویسندگان

چکیده

Solving a longstanding problem on equiangular lines, we determine, for each given fixed angle and in all sufficiently large dimensions, the maximum number of lines pairwise separated by angle. Fix $0 < \alpha 1$. Let $N_\alpha(d)$ denote through origin $\mathbb{R}^d$ with common $\arccos \alpha$. $k$ minimum (if it exists) vertices graph whose adjacency matrix has spectral radius exactly $(1-\alpha)/(2\alpha)$. If $k \infty$, then $N_\alpha(d) = \lfloor k(d-1)/(k-1) \rfloor$ $d$, otherwise d + o(d)$. In particular, $N_{1/(2k-1)}(d) every integer $k\ge 2$ $d$. A key ingredient is new result theory: connected bounded degree sublinear second eigenvalue multiplicity.

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ژورنال

عنوان ژورنال: Annals of Mathematics

سال: 2021

ISSN: ['1939-8980', '0003-486X']

DOI: https://doi.org/10.4007/annals.2021.194.3.3