Half-integrality, LP-branching, and FPT algorithms

Y Iwata, M Wahlstrom, Y Yoshida - SIAM Journal on Computing, 2016 - SIAM
A recent trend in parameterized algorithms is the application of polytope tools to fixed-
parameter tractable (FPT) algorithms eg, Cygan et al., FOCS 2011, 52nd Annual Symposium …

Linear-time kernelization for feedback vertex set

Y Iwata - arxiv preprint arxiv:1608.01463, 2016 - arxiv.org
In this paper, we propose an algorithm that, given an undirected graph $ G $ of $ m $ edges
and an integer $ k $, computes a graph $ G'$ and an integer $ k'$ in $ O (k^ 4 m) $ time such …

0/1/all CSPs, half-integral A-path packing, and linear-time FPT algorithms

Y Iwata, Y Yamaguchi, Y Yoshida - 2018 IEEE 59th Annual …, 2018 - ieeexplore.ieee.org
A recent trend in the design of FPT algorithms is exploiting the half-integrality of LP
relaxations. In other words, starting with a half-integral optimal solution to an LP relaxation …

A weighted linear matroid parity algorithm

S Iwata, Y Kobayashi - Proceedings of the 49th Annual ACM SIGACT …, 2017 - dl.acm.org
The matroid parity (or matroid matching) problem, introduced as a common generalization of
matching and matroid intersection problems, is so general that it requires an exponential …

[PDF][PDF] Packing even directed circuits quarter-integrally

M Gorsky, K Kawarabayashi, S Kreutzer… - Proceedings of the 56th …, 2024 - dl.acm.org
We prove the existence of a computable function f∶ ℕ→ ℕ such that for every integer k and
every digraph D, either D contains a collection C of k directed cycles of even length such that …

[HTML][HTML] Packing non-zero A-paths via matroid matching

S Tanigawa, Y Yamaguchi - Discrete Applied Mathematics, 2016 - Elsevier
A Γ-labeled graph is a directed graph G in which each edge is associated with an element of
a group Γ by a label function ψ: E (G)→ Γ. For a vertex subset A⊆ V (G), a path (in the …

A Faster Deterministic Algorithm for Mader's -Path Packing

S Iwata, H Kinoshita - arxiv preprint arxiv:2411.18292, 2024 - arxiv.org
Given an undirected graph $ G=(V, E) $ with a set of terminals $ T\subseteq V $ partitioned
into a family $\mathcal {S} $ of disjoint blocks, find the maximum number of vertex-disjoint …

Finding a path with two labels forbidden in group-labeled graphs

Y Kawase, Y Kobayashi, Y Yamaguchi - Journal of Combinatorial Theory …, 2020 - Elsevier
The parity of the length of paths and cycles is a classical and well-studied topic in graph
theory and theoretical computer science. The parity constraints can be extended to label …

Shortest disjoint S-paths via weighted linear matroid parity

Y Yamaguchi - 27th International Symposium on Algorithms and …, 2016 - drops.dagstuhl.de
Mader's disjoint S-paths problem unifies two generalizations of bipartite matching:(a) non-
bipartite matching and (b) disjoint s–t paths. Lovász (1980, 1981) first proposed an efficient …

Finding a shortest non-zero path in group-labeled graphs

Y Iwata, Y Yamaguchi - Combinatorica, 2022 - Springer
We study a constrained shortest path problem in group-labeled graphs with nonnegative
edge length, called the shortest non-zero path problem. Depending on the group in …