Krivine rounding constant ($c_K=\frac{2}{\pi }\log (1+\sqrt{2})$)

The Krivine rounding scheme yields $c_K=0.56109985\dots$ as its guaranteed objective factor. It is obtained by normalizing $\sinh t=1$, so $t=\mathrm{arsinh}(1)$ and $c_K=2t/\pi$. This proof gives a valid universal factor for the bipartite sign problem, not a proof that it is optimal.