2 problems

Let $\mathcal{Y}\to B$ be the one-parameter family of smooth, multiply connected Calabi–Yau threefolds over … where $\xi$ is a primitive fifth root of unity, and write $Y_t$ for th…

Let $M$ be a fixed differentiable manifold underlying a K3 surface, and let … and $'$. Write $[]$ and $[']$ for their periods in ${\mathbb P}(H^2(M,{\mathbb C}))$, and let…