Month: May 2023

The 21st KMGS will be held on June 1st, Thursday, at Natural Science Building (E6-1) Room 1501.
We invite a speaker Hansol Kim from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

Slot (AM 11:50~PM 12:30)
[Speaker] 김한솔 (Hansol Kim)  from Dept. of Mathematical Sciences, KAIST, supervised by Prof. 임보해 교수님 (Bo-Hae Im)
[Title] Problems on Torsion Subgroups of Elliptic Curves over Number Fields 
[Discipline] Number Theory
[Abstract]
We introduce elliptic curves, their Mordell-Weil group structure, and isogenies over number fields. At the last of the talk, some results on the torsion subgroups of Mordell-Weil groups of elliptic curves defined over a number field will be given.The results are joint works with my advisor Bo-Hae Im.
[Language] Korean 

The 20th KMGS will be held on May 18th, Thursday, at Natural Science Building (E6-1) Room 1501.
We invite a speaker Jungho Ahn from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

Slot (AM 11:50~PM 12:30)
[Speaker] 안정호 (Jungho Ahn) from Dept. of Mathematical Sciences, KAIST, supervised by Prof. 엄상일 교수님(Sang-il Oum)
[Title] Introduction to Kernelization
[Discipline] Graph Theory, Complexity Theory
[Abstract]
We introduce concepts of parameterized complexity, especially, kernelization. Kernelization is a polynomial-time preprocessing algorithm that converts a given instance for a problem to a smaller instance while keeping the answer to the problem. Delicate kernelization mostly boosts the speed of solving the problem. We explain standard techniques in kernelizations, for instance, the sunflower lemma. Most optimization problems can be reformulated in the Hitting Set problem format, and the sunflower lemma gives us a simple yet beautiful kernelization for the problem. We further introduce our recent work about the Hitting Set problem on sparse graph classes.
[Language] Korean but English if it is requested.

The 19th KMGS will be held on May 11th, Thursday, at Natural Science Building (E6-1) Room 1501.
We invite a speaker Doyoung Choi from the Dept. of Mathematical Sciences, KAIST.
The abstract of the talk is as follows.

Slot (AM 11:50~PM 12:30)
[Speaker] Doyoung Choi(최도영) from Dept. of Mathematical Sciences, KAIST, supervised by Prof. Yongnam Lee (이용남 교수님)
[Title] Degree of the 3-secant variety
[Discipline] Algebraic geometry
[Abstract] 
In this talk, we present a formula for the degree of the 3-secant variety of a nonsingular projective variety embedded by a 3-very ample line bundle. The formula is provided in terms of Segre classes of the tangent bundle of a given variety. We use the generalized version of double point formula to reduce the calculation into the case of the 2-secant variety. Due to the singularity of the 2-secant variety, we use secant bundle as a nonsingular birational model and compute multiplications of desired algebraic cycles.
[Language] Korean