[Notice] 60th KMGS on September 10 (Thu), 2026

The 60th KMGS will be held on September 10, Thursday, at the Natural Science Building (E6-1) Room 1410. We invite a speaker Beomho Kim from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

[Speaker] 김범호 (Beomho Kim) from Dept. of Mathematical Sciences, KAIST, supervised by Prof. 임보해 (Bo-Hae Im)
[Title] Elliptic Curves over Global Function Fields
[Discipline] Number Theory
[Abstract]
Elliptic curves are fundamental objects in modern number theory, connecting algebraic geometry and arithmetic.In this talk, I will give an introductory overview of elliptic curves and their arithmetic, comparing the number field and function field settings and highlighting their similarities and differences. I will then present recent results on elliptic curves of analytic rank one and their ranks over certain ring class fields, based on joint work with Seokhyun Choi and Bo-Hae Im.
[Language] Korean

[Notice] 53rd KMGS on December 4 (Thu), 2025

The 53rd KMGS will be held on December 4, Thursday, at the Natural Science Building (E6-1) Room 1410. We invite a speaker Donghan Kim from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

[Speaker] 김동한(Donghan Kim) from Dept. of Mathematical Sciences, KAIST, supervised by  Prof. 김우진 (Woojin Kim)
[Title] Persistent Homology is Complementary to the Weisfeiler–Leman Test
[Discipline] Algebraic Topology
[Abstract]
We analyze the expressive power of persistent homology obtained purely from Vietoris–Rips filtrations on the shortest-path metric of a graph, without using any node features. We show that the verbose diagram completely determines the clique numbers in all dimensions, demonstrating that persistent homology captures rich combinatorial structure. We further construct, for every integer k, explicit graph pairs that the k-dimensional Weisfeiler–Leman test cannot distinguish but persistent homology can. These results demonstrate that persistent homology and the Weisfeiler–Leman test are fundamentally incomparable.
[Language] Korean

[Notice] 52nd KMGS on November 20 (Thu), 2025

The 52nd KMGS will be held on November 20, Thursday, at the Natural Science Building (E6-1) Room 1410. We invite a speaker Yoochan Han from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

[Speaker] 한유찬 (Yoochan Han) from Dept. of Mathematical Sciences, KAIST, supervised by  Prof. 이지운 (Ji Oon Lee)
[Title] Spectral Properties and Weak Detection in Stochastic Block Models
[Discipline] Probability Theory
[Abstract]
In this talk, I will introduce basic ideas from random matrix theory and explain how spectral methods are used to study random graphs. Focusing on the stochastic block model, I will present recent results showing a sharp phase transition in the extreme eigenvalues and a central limit theorem for linear spectral statistics. These results lead to a simple spectral test for detecting the presence of communities. This talk is based on the joint work with Prof. Ji Oon Lee and Dr. Wooseok Yang.
[Language] Korean

[Notice] 51st KMGS on November 6 (Thu), 2025

The 51st KMGS will be held on November 6, Thursday, at the Natural Science Building (E6-1) Room 1410. We invite a speaker Chanyoung Kim from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

[Speaker] 김찬영(Chanyoung Kim) from Dept. of Mathematical Sciences, KAIST, supervised by  Prof. 하우석 (Wooseok Ha)
[Title] Quantum spectral operator learning for solving partial differential equations
[Discipline] Applied Mathematics
[Abstract]
Partial differential equations (PDEs) are central to modeling physical and engineering systems. Operator learning approximates their solution operators, enabling fast inference after training across diverse problem instances and strong generalization. While recent advances have proposed unsupervised methods that mitigate the cost of data generation, classical neural network–based approaches remain computationally expensive for high-dimensional operators and fine-resolution problems. To address these challenges, we propose a quantum–classical hybrid framework for unsupervised spectral operator learning. Our approach predicts spectral coefficients using quantum circuits, with gate parameters mapped from PDE instances (e.g., forcing functions or PDE parameters) via a classical neural network. To improve efficiency and feasibility, we introduce a training objective that requires fewer measurement repetitions than standard variational quantum linear solvers (VQLS). With this, we design shallower circuits by replacing controlled-unitary gates with direct Pauli measurements, which in turn allows grouping of commuting measurement operators for further reduction in runtime. The objective also resolves the sign ambiguity inherent in standard VQLS and guarantees recovery of the correct solution sign for PDEs. Overall, our framework reduces the computational cost and improves solution accuracy of VQLS, while also demonstrating the potential efficiency and scalability advantages of quantum operator learning over classical machine learning approaches. We validate our framework on one- and two-dimensional reaction–diffusion, Helmholtz, and convection–diffusion equations under diverse boundary conditions, achieving relative errors below 1%.
[Language] English

[Notice] 50th KMGS on October 2 (Thu), 2025

The 50th KMGS will be held on October 2, Thursday, at the Natural Science Building (E6-1) Room 1410. We invite a speaker Dongha Lee from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

[Speaker] 이동하 (Dongha Lee) from Dept. of Mathematical Sciences, KAIST, supervised by  Prof. 박진성 (Jinsung Park, KIAS) and Prof. 백형렬 (Hyungryul Baik, KAIST)
[Title] Minimal Surfaces in Riemann-Cartan Geometry
[Discipline] Differential Geometry
[Abstract]
In this talk, we extend the classical theory of minimal surfaces studied in Euclidean and Riemannian geometry to a more general framework in Weitzenböck and Riemann-Cartan geometry, which incorporates torsion. After providing a gentle introduction to minimal surface theory, we present theorems that generalize classical results concerning the holomorphic nature of the Hopf differential, the conformality of the Gauss map, and the minimality of surfaces.
[Language] English