# Next Meeting

### University of Cambridge - Thursday 7th February 2019

The next meeting of the COW will take place at the University of Cambridge on Thursday 7th February 2019. The meeting will start at 2pm. All talks will be held in room MR9 in the Centre for Mathematical Sciences.

### Schedule

Time |
Speaker |
Title |

2:00pm | Michel van Garrel | Open-Closed Duality is Mirror to the Double Suspension |

3:30pm | Diane Maclagan | TBA |

5:00pm | Maksym Fedorchuk | Standard Models of Low Degree del Pezzo Fibrations via GIT for Hilbert Points |

### Abstracts

**Michel van Garrel (Warwick) - Open-Closed Duality is Mirror to the Double Suspension**- Let S be a toric del Pezzo surface and let E be a smooth anticanonical divisor on it. In this talk, I consider both the log geometry given by the pair (S,E) and the local geometry given by the total space of O(-E). The claim is that for the purpose of genus 0 mirror symmetry, they form equivalent geometries. The genus 0 A-model invariants are related to each other by a version of open-closed duality and the B-model geometries by the double suspension. After describing the relevant constructions, I will formulate a theorem of relative mirror symmetry in this context.
**Diane Maclagan (Warwick) - TBA**- Abstract forthcoming.
**Maksym Fedorchuk (Boston College) - Standard Models of Low Degree del Pezzo Fibrations via GIT for Hilbert Points**- A del Pezzo fibration is one of the natural outputs of the Minimal Model Program for threefolds. At the same time, geometry of an arbitrary del Pezzo fibration can be unsatisfying due to the presence of non-integral fibers and terminal singularities of an arbitrarily large index. In 1996, Corti developed a program of constructing 'standard models' of del Pezzo fibrations within a fixed birational equivalence class. Standard models enjoy a variety of desired properties, one of which is that all of their fibers are Q-Gorenstein integral del Pezzo surfaces. Corti proved the existence of standard models for del Pezzo fibrations of degree d ≥ 2, with the case of d = 2 being the most difficult. The case of d = 1 remained a conjecture. In 1997, Kollár recast and improved Corti’s result in degree d = 3 using ideas from the Geometric Invariant Theory for cubic surfaces. I will present a generalization of Kollár’s approach in which we develop notions of stability for families of low degree (d ≤ 2) del Pezzo fibrations in terms of their Hilbert points (i.e., low degree equations cutting out del Pezzos). A correct choice of stability and a bit of enumerative geometry then leads to (very good) standard models in the sense of Corti. This is a joint work with Hamid Ahmadinezhad and Igor Krylov.

This page is maintained by Alan Thompson and was last updated on 23/01/19. Please email comments and corrections to A.M.Thompson (at) lboro.ac.uk.