= Reflected real-basis CHSH strategy
{title2=$p_{\mathrm{win}}=(3+t-t^2)/4,\quad t=\cos2\theta$}
For the <Bell state> $|\phi_+\rangle$, let both zero-input measurements use the <computational basis>, and let the one-input bases be rotated by $\theta$ for Alice and $-\theta$ for Bob in the real <qubit> plane. In the <CHSH game>, the four conditional winning <probabilities> are $1,\cos^2\theta,\cos^2\theta,\sin^2(2\theta)$. They follow by contraction of the <Bell state> with vectors from the real <orthonormal bases> used for the <basic measurements>. Their average is the displayed expression. On $0\leq\theta\leq\pi/2$, this beats $3/4$ exactly when $0<\theta<\pi/4$ and reaches $13/16$ at $\theta=\pi/6$, since $t-t^2=1/4-(t-1/2)^2$.
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