On an example of Aspinwall, Morrison, and Szendroi
Abstract
We study the cohomology of a 1-parameter family Yt of Calabi-Yau 3-folds introduced by Aspinwall and Morrison, related to the mirror quintic family. Szendroi proved that Yt, Yxi t, ..., Yxi4 t, where xi is a fifth root of unity, have the same rational Hodge structure but are not isomorphic, and conjectured that they are not birational or even derived equivalent. We confirm this by proving that their integral Hodge structures are different, and discuss how this fits with known Torelli-type theorems and counterexamples.
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