Pfaffian Calabi-Yau threefolds, Stanley-Reisner schemes and mirror symmetry

Abstract

Calabi-Yau manifolds are important objects in algebraic geometry and in theoretical physics. A hypothesis of mirror symmetry is that Calabi-Yau manifolds of dimension 3 come in pairs, with the Hodge numbers of one manifold mirroring the Hodge numbers of the other. In this thesis, Calabi-Yau manifolds are constructed by smoothing Stanley-Reisner schemes of triangulations of 3-spheres. The triangulations of the 3-sphere with 7 or 8 vertices have been constructed and classified by Gr\"unbaum and Sreedharan (1967). In this thesis we characterize the Calabi-Yau manifolds obtained from the triangulations with 7 vertices. They are embedded in six-dimensional projective space. Mirrors of such manifolds are constructed by resolution of singularities performed on a singular fiber in the deformation family of the Stanley-Reisner scheme. In this way, we reproduce the mirror by R{\o}dland (1999) of a degree 14 pfaffian Calabi-Yau threefold, and the mirror candidate by B\"ohm (2007) of a degree 13 pfaffian Calabi-Yau threefold. In the latter case we verify that the Hodge numbers in fact constitute a mirror, using toric geometry.