These notes were taken during the talk given by Tony Yue YU (Caltech)
Definition (Calabi-Yau variety):
A smooth projective variety is called Calabi-Yau if its canonical bundle is trivial, i.e., it has nowhere vanishing holomorphic volume form.
Examples are elliptic curves, abelian varieties, K3 surfaces, hypersurface of degree d+1 in
Mirror symmetry is conjectural duality between Calabi-Yau varieties:
Calabi-Yau variety mirror variety
such that geometric relations hold between and : Hodge structure, Gromov-Witten invariants, Fukaya categories, derived category of coherent sheaves, SY2 torus fibration, etc.
Further study reveals that mirror symmetry is actually a duality between “maximal degenerating family” of Calabi-Yau varieties.
Classical approach to Gromov-Witten theory is via Perfect obstruction theory (by Behrend-Fantechi, Li-Tian)