Meike Hatzel gave a talk on a structural characterization of digraphs not immersing a cylindrical grid at the Discrete Math Seminar

On August 5, 2026, Meike Hatzel from TU Darmstadt gave a talk at the Discrete Math Seminar on a structural characterization of digraphs not immersing a cylindrical grid. The title of her talk was "Directed tree-cutwidth and immersions".

dimag.ibs.re.kr

Tomohiro Koana gave a talk on a faster FPT algorithm for expanding a subgraph to be a 2-connected subgraph of a given graph by adding at most k edges

On August 4, 2026, Tomohiro Koana from University of Tokyo gave a talk at the Discrete Math Seminar on a single-exponential fixed-parameter algorithm for enlarging a subgraph with at most k edges to make a 2-connected subgraph of a given graph. The title of his talk was "A Single-Exponential FPT Algorithm for 2-Vertex-Connectivity Augmentation".

dimag.ibs.re.kr

Reducing CMSO to Unbreakable Graphs Cannot be Computable

Lokshtanov, Ramanujan, Saurabh, and Zehavi [ICALP 2018] proved that for any CMSO formula $ϕ$, testing $ϕ$ on arbitrary graphs can be reduced to testing it on $(q,k)$-unbreakable graphs for appropriate...

arxiv.org

Redirecting

doi.org

Additive decompositions of multiplicative subgroups in prime fields: a self-contained approach

Sárközy conjectured that the nonzero quadratic residues modulo a sufficiently large prime have no nontrivial additive decomposition. Hanson and Petridis proved the conjecture for almost all primes, an...

arxiv.org

Intersection patterns in spaces with a forbidden homological minor | Forum of Mathematics, Sigma | Cambridge Core

Intersection patterns in spaces with a forbidden homological minor - Volume 14

doi.org

Strong invariants and Tverberg numbers in convexity spaces

Helly, Carathéodory, and Radon numbers encode three kinds of finite certificates in a convexity space: for the emptiness of an intersection, for membership in a convex hull, and for the existence of i...

arxiv.org

Welcome Olga Medrano Martín del Campo, a new member of the IBS Discrete Mathematics Group

The IBS discrete mathematics group welcomes Dr. Olga Medrano Martín del Campo, a new research fellow at the IBS Discrete Mathematics Group from August 1, 2026. She received her Ph.D. from the University of Chicago under the supervision of Prof. Maryanthe Malliaris. She is interested in Learning in Theoretical Computer Science and connections to Logic and Combinatorics.

dimag.ibs.re.kr

Welcome Rifakat Alim Rashkee, a new graduate student of the IBS Discrete Mathematics Group

The IBS Discrete Mathematics Group welcomes Rifakat Alim Rashkee, a new graduate student of the Discrete Mathematics Group from August 1, 2026. He received his B.S. degree from KAIST and entered the Department of Mathematical Sciences at KAIST as a graduate student on March 2026. His advisor is Sebastian Wiederrecht.

dimag.ibs.re.kr

Saturated Partial Embeddings of Planar Graphs

In this work, we study how far one can deviate from optimal behavior when embedding a planar graph. For a planar graph $G$, we say that a plane subgraph $H\subseteq G$ is a \textit{plane-saturated sub...

arxiv.org

On Sparsity Conditions Guaranteeing a Fractional Coloring

A graph has an ( a : b ) -coloring if there exists an assignment from the vertices to subsets of { 1 , … , a } with size b such that adjacent vertices are assigned disjoint subsets. Odd girth at l...

doi.org

Multiplicative subgroups are not restricted sumsets

We determine exactly which proper multiplicative subgroups of a prime field can be represented as a restricted sumset of the form $A\mathbin{\widehat{+}} A=\{a+a':a,a'\in A,\ a\ne a'\}$. We prove that...

arxiv.org

Stephan Kreutzer gave a talk on the disjoint paths problem at the Discrete Math Seminar

On July 28, 2026, Stephan Kreuter from TU Berlin gave a talk on the disjoint paths problem on undirected graphs and directed graphs at the Discrete Math Seminar. The title of his talk was "Disjoint Paths in Graphs and Digraphs".

dimag.ibs.re.kr

Formalizing Flag Algebras in Lean

Razborov's flag algebra method is a powerful tool for proving asymptotic inequalities in extremal graph theory, often reducing the task to finding a finite certificate by semidefinite programming. We ...

arxiv.org

The Excluded Vertex-Minors and Pivot-Minors for Rank-Width at Most Two

We determine both the excluded vertex-minors and the excluded pivot-minors for the class of graphs of rank-width at most two. Up to local equivalence and graph isomorphism, there are exactly 25 exclud...

arxiv.org

Multiplicative irreducibility of shifted multiplicative subgroups in the extremal case

In a recent breakthrough, Kalmynin proved a conjecture of Sárközy on additive irreducibility of the set of quadratic residues in a prime field. More recently, Kim, Yip, and Yoo initiated the study of ...

arxiv.org

Yu Deng Wins the Fields Medal 2026 for His Work on the Random Data Problem | Quanta Magazine

Before he won a Fields Medal for his pioneering work balancing randomness and order, Yu Deng first had to achieve equilibrium in his own life.

quantamagazine.org

Group vertex-arboricity of group-labelled graphs

We introduce the vertex-arboricity of group-labelled graphs. For an abelian group $Γ$, a $Γ$-labelled graph is a graph whose edges are labelled by elements of $Γ$. For an abelian group $Γ$ and $A\subs...

arxiv.org

Zichao Dong gave a talk on the maximum size of a set family in which, for each i≤k, every intersection of i members has a prescribed parity at the Discrete Math Seminar

On July 21, 2026, Zichao Dong from the IBS Extremal Combinatorics and Probability Group a talk on the maximum size of a set family in which, for each i ≤ k, every intersection of i members has a prescribed parity at the Discrete Math Seminar. The title of his talk was "k-wise odd-even towns".

dimag.ibs.re.kr

A proof of the cycle double cover conjecture by OpenAI: An exposition

The cycle double cover conjecture states that every bridgeless graph has a list of cycles such that every edge is in exactly two of them. In July 2026, OpenAI announced a proof. This exposition presen...

arxiv.org

Maximum Partial List H-Coloring on P_5-free graphs in polynomial time

In this article we show that Maximum Partial List H-Coloring is polynomial-time solvable on P_5-free graphs for every fixed graph H. In particular, this implies that Maximum k-Colorable Subgraph is po...

arxiv.org

A proof of the cycle double cover conjecture by OpenAI: An exposition · Sang-il Oum (엄상일)

I have written an exposition of a proof of the cycle double cover conjecture announced by OpenAI in July 11, 2026, while preparing a talk at the Discrete …

sangil.dimag.kr

FOCS 2026 – Accepted Papers

sanjeevkhanna.org

Sang-il Oum (엄상일) gave a talk at the Discrete Math Seminar on a recent proof of the cycle double cover conjecture by OpenAI

On July 16, 2026, Sang-il Oum from the IBS Discrete Mathematics Group gave a talk on a recent proof the cycle double cover conjecture by OpenAI at the Discrete Math Seminar. The title of his talk was "A proof of the cycle double cover conjecture by OpenAI".

dimag.ibs.re.kr

Yaobin Chen gave a talk on the maximum size of a subset in general position of a random subset of a finite-dimensional vector space over a finite field

On July 14, 2026, Yaobin Chen from the IBS Extremal Combinatorics and Probability Group gave a talk at the Discrete Math Seminar on the maximum size of a subset in general position of a random subset of a finite-dimensional vector space over a finite field. The title of his talk was "Maximum in-general-position set in a random subset of $\mathbb{F}_q^d$".

dimag.ibs.re.kr

2026 Workshop on Topological Combinatorics Successfully Held at GIST

The 2026 Workshop on Topological Combinatorics was successfully held at Gwangju Institute of Science and Technology (GIST) from June 28 to July 11, 2026. The workshop was organized by Andreas Holmsen (KAIST & IBS DIMAG), Jinha Kim (Chonnam National University & IBS DIMAG), and Minki Kim (GIST), with support from GIST, IBS Discrete Mathematics Group (DIMAG), and the National Research Foundation of Korea (NRF). 

dimag.ibs.re.kr

Welcome Yaobin Chen and Simón Piga, new members of IBS ECOPRO

The IBS Discrete Mathematics Group welcomes Dr. Yaobin Chen and Dr. Simón Piga, new research fellows at the IBS Extremal Combinatorics and Probability Group, starting July 1, 2026. Yaobin Chen received his Ph.D. from Fudan University under the supervision of Prof. Hehui Wu. He is interested in extremal graph theory and combinatorics. Simón Piga received his Ph.D. from the University of Hamburg under the supervision of Prof. Mathias Schacht. Until recently, he was a postdoctoral researcher at the Czech Academy of Science. He is interested in extremal and probabilistic combinatorics.

dimag.ibs.re.kr

Ting-Wei Chao gave a talk on a variation of the odd town problem at the Discrete Math Seminar

On July 10, 2026, Ting-Wei Chao from MIT gave a talk at the Discrete Math Seminar on a variation of the odd town problem. The title of his talk was "The Oddtown Problem Modulo a Composite Number".

dimag.ibs.re.kr

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