演講公告

演講

  • 演講時間:2024年06月14日(五)
    Tight Bound on Joints Problem and Partial Shadow Problem
    講者:趙庭偉博士

    .演講時間:2024年6月14日(五) 11:00 –12:00
    .演講地點:(光復校區) 科學一館223室
    .摘要內容:

    Abstract
    Given a set of lines in R^d, a joint is a point contained in d linearly independent lines. Guth and Katz showed that N lines can determine at most O(N^{3/2}) joints in R^3 via the polynomial method.
    Yu and I proved a tight bound on this problem, which also solves a conjecture proposed by Bollob\'as and Eccles on the partial shadow problem. It is surprising to us that the only known proof to this purely extremal graph theoretic problem uses incidence geometry and the polynomial method.

    相關檔案:Talk_1130614.pdf

  • 演講時間:2024年03月15日(五)
    Factorizing three-dimensional smooth flops
    講者:陳星谷博士(韓國高級研究所)

    .演講時間:2024年3月15日(五) 上午11:00 –12:00
    .演講地點:(光復校區) 科學一館307室
    .摘要內容:

    Abstract. A flop is a special birational transformation which produces a symmetry between two algebraic varieties. In this talk we will give an explicit description for three-dimensional smooth flops over complex numbers by factorizing them as a sequence of smooth blow-ups and blow-downs.

    相關檔案:Talk_1130315.pdf

  • 演講時間:2024年01月24日(三)
    Towards decompositions of small transitions of Calabi-Yau 3-folds
    講者:王賜聖博士 (中研院數學所)

    .演講時間:2024年1月24日(三) 14:00 –15:00
    .演講地點:(光復校區) 科學一館223室
    .摘要內容:

    Abstract.
    The Calabi-Yau manifolds play an important role in geometry and mathematical physics. There is a small transition process for two Calabi-Yau 3-folds, a small birational contraction followed by a complex smoothing. The simplest one is a conifold transition. In this talk, I will introduce a primitive subclass of small transitions as the building blocks and investigate the relation between conifold transitions and primitive ones.

    相關檔案:Talk_1130124.pdf

  • 演講時間:2024年01月12日(五)
    Extensions of Yamamoto-Nayak's asymptotic theorem
    講者:Tin-Yau Tam 教授 (美國內華達大學雷諾分校)

    .演講時間:2024年1月12日 (五) 11:00 - 12:00
    .演講地點:(光復校區)科學一館 223 室
    .摘要內容:

    詳情請見附件。

    相關檔案:Talk_20240112 .pdf

  • 演講時間:2023年12月19日(二)
    Stable estimation of time-varying treatment effects using an approximate multiply robust estimator
    講者:田栗正隆教授 (日本東京醫科大學)

    .演講時間:2023年12月19日 (二) 11:00 - 12:00
    .演講地點:光復校區 綜合一館四樓427室
    .摘要內容:

    報名表單 (有意參加者請協助填寫報名表單,以利場地安排,謝謝您的配合)
    https://forms.gle/nzwnU6Hcn7H9yo8u7

    Abstract
    In longitudinal studies involving time-varying treatments, time-dependent confounding can occur if the time-dependent covariates are influenced by past treatments. Multiply robust estimators, which are based on augmented inverse probability (AIPW) estimating equations, have been proposed to protect against model misspecification(Bang and Robins, 2005; Rotnitzky et al., 2017). However, these estimators have large variances when there is significant variability in inverse probability weights. To address this issue, we propose an approximate multiply robust estimator based on stratification of inverse probability weights.For the point treatment, our proposed method corresponds to the approach combining outcome regression models and propensity score stratification (Lunceford and Davidian, 2004). We will present the results of simulations comparing the proposed estimator with existing estimators.

    相關檔案:Postor.jpg

  • 演講時間:2023年12月15日(五)
    Conformal Geometry on 4-manifolds
    講者:張聖容教授(普林斯頓大學數學系)

    .演講時間:2023年12月15日(五) 11:00 - 12:00
    .演講地點:(光復校區) 科學一館223室
    .摘要內容:

    In this talk, I will give a survey talk on results and PDE techniques in conformal geometry.
    On 4-manifolds, one of the key ingredients is the study of the integrand of the Chern-
    Gauss-Bonnet formula. The part that involves the Ricci tensor gives a fully non-linear PDE
    known as the second elementary symmetric equation. It turns out this PDE can be studied
    via a 4-th order linear operator (part of the family of GJMS operator) and its associated 4-th
    order curvature called the Q-curvature. I will explain the connection and give an application
    of using this concept to compute the renormalized volume.
    As another application, we will study the problem of ”conformal filling in” in ADS/CFT
    theory. Namely, given a manifold (Mn; [h]), when is it the boundary of a conformally compact
    Einstein manifold ( Xn+1; g+) with r2
    g+|M = h for some defining function r on Xn+1?
    The model example is the n-sphere as the conformal infinity of the hyperbolic (n+1) ball.

    相關檔案:Talk_20231215.pdf