Bukh–Balla–Dräxler–Keevash–Sudakov conjecture on equiangular-line bounds

Let $r\geq2$ be an integer. For $\alpha>0$, let $N_\alpha(d)$ denote the maximum number of equiangular lines in $\mathbb{R}^d$ with common absolute inner product $\alpha$.

Bukh–Balla–Dräxler–Keevash–Sudakov conjecture. For sufficiently large $n$,

$$N_{\frac{1}{2r-1}}(d)=\frac{r(n-1)}{r-1}+O(1).$$

This conjecture proposes a general asymptotic formula for equiangular-line systems whose common angle is the reciprocal of an odd integer. The statement uses $n$ in its formula although the surrounding notation defines the parameter as $d$; this notation mismatch should be checked against the source.