Deformations of calibrations, {Calabi-Yau, HyperKähler, and Spin(7) structures}
arXiv:math/0204288
Abstract
We shall develop a new deformation theory of geometric structures in terms of closed differential forms. This theory is a generalization of Kodaira -Spencer theory and further we obtain a criterion of unobstructed deformations. We apply this theory to certain geometric structures: Calabi-Yau, HyperKähler, $\G$ and $\Spin$ structures and show that these deformation spaces are smooth in a systematic way.
54pages