12 citations · 37 across the 22 of their papers we have counts for
28 papers
A Matroid Generalization of Weighted Popular Matching: Characterization and Algorithm
Yuni Iwamasa, Yusuke Kobayashi, Ryoga Mahara +1
We study a problem that unifies two major generalizations of popular matchings in the one-sided preference model. In a bipartite graph in which each vertex, or applicant, on one si…
Towards discrete convex analysis over classical root systems
Yuni Iwamasa
Discrete Convex Analysis (DCA) is a discrete analog of continuous convex analysis, originally proposed as a unified theoretical framework for efficiently solvable combinatorial opt…
A general framework for finding diverse solutions via network flow and its applications
Yuni Iwamasa, Tomoki Matsuda, Shunya Morihira +1
In this paper, we present a general framework for efficiently computing diverse solutions to combinatorial optimization problems. Given a problem instance, the goal is to find …
Computing diverse pair of solutions for tractable SAT
Tatsuya Gima, Yuni Iwamasa, Yasuaki Kobayashi +3
In many decision-making processes, one may prefer multiple solutions to a single solution, which allows us to choose an appropriate solution from the set of promising solutions tha…
Basis sequence reconfiguration in the union of matroids
Tesshu Hanaka, Yuni Iwamasa, Yasuaki Kobayashi +2
Given a graph and two spanning trees and in , Spanning Tree Reconfiguration asks whether there is a step-by-step transformation from to such that all inter…
Homotopy types of Hom complexes of graph homomorphisms whose codomains are cycles
Soichiro Fujii, Yuni Iwamasa, Kei Kimura +2
For simple graphs and , the Hom complex is a polyhedral complex whose vertices are the graph homomorphisms and whose edges connect the pairs of…
Algorithmic aspects of semistability of quiver representations
Yuni Iwamasa, Taihei Oki, Tasuku Soma
We study the semistability of quiver representations from an algorithmic perspective. We present efficient algorithms for several fundamental computational problems on the semistab…
On the sizes of BDDs and ZDDs representing matroids
Hiromi Emoto, Yuni Iwamasa, Shin-ichi Minato
Matroids are often represented as oracles since there are no unified and compact representations for general matroids. This paper initiates the study of binary decision diagrams (B…
Finding a Maximum Restricted -Matching via Boolean Edge-CSP
Yuni Iwamasa, Yusuke Kobayashi, Kenjiro Takazawa
The problem of finding a maximum -matching without short cycles has received significant attention due to its relevance to the Hamilton cycle problem. This problem is generalize…
Algebraic combinatorial optimization on the degree of determinants of noncommutative symbolic matrices
Hiroshi Hirai, Yuni Iwamasa, Taihei Oki +1
We address the computation of the degrees of minors of a noncommutative symbolic matrix of form \[ A[c] := \sum_{k=1}^m A_k t^{c_k} x_k, \] where are matrices over a field $\…
Reconfiguration of Time-Respecting Arborescences
Takehiro Ito, Yuni Iwamasa, Naoyuki Kamiyama +4
An arborescence, which is a directed analogue of a spanning tree in an undirected graph, is one of the most fundamental combinatorial objects in a digraph. In this paper, we study…
Characterizations of the set of integer points in an integral bisubmodular polyhedron
Yuni Iwamasa
In this note, we provide two characterizations of the set of integer points in an integral bisubmodular polyhedron. Our characterizations do not require the assumption that a given…
Reconfiguration of colorings in triangulations of the sphere
Takehiro Ito, Yuni Iwamasa, Yusuke Kobayashi +4
In 1973, Fisk proved that any -coloring of a -colorable triangulation of the -sphere can be obtained from any -coloring by a sequence of Kempe-changes. On the other han…
Rerouting Planar Curves and Disjoint Paths
Takehiro Ito, Yuni Iwamasa, Naonori Kakimura +5
In this paper, we consider a transformation of disjoint paths in a graph. For a graph and a pair of disjoint paths and connecting the same set o…
Reforming an Envy-Free Matching
Takehiro Ito, Yuni Iwamasa, Naonori Kakimura +5
We consider the problem of reforming an envy-free matching when each agent is assigned a single item. Given an envy-free matching, we consider an operation to exchange the item of…
Independent set reconfiguration on directed graphs
Takehiro Ito, Yuni Iwamasa, Yasuaki Kobayashi +4
\textsc{Directed Token Sliding} asks, given a directed graph and two sets of pairwise nonadjacent vertices, whether one can reach from one set to the other by repeatedly applying a…
Monotone edge flips to an orientation of maximum edge-connectivity à la Nash-Williams
Takehiro Ito, Yuni Iwamasa, Naonori Kakimura +6
We initiate the study of -edge-connected orientations of undirected graphs through edge flips for . We prove that in every orientation of an undirected -edge-conne…
Reconfiguring (non-spanning) arborescences
Takehiro Ito, Yuni Iwamasa, Yasuaki Kobayashi +3
In this paper, we investigate the computational complexity of subgraph reconfiguration problems in directed graphs. More specifically, we focus on the problem of reconfiguring arbo…
Quantaloidal Approach to Constraint Satisfaction
Soichiro Fujii, Yuni Iwamasa, Kei Kimura
The constraint satisfaction problem (CSP) is a computational problem that includes a range of important problems in computer science. We point out that fundamental concepts of the…
A combinatorial algorithm for computing the entire sequence of the maximum degree of minors of a generic partitioned polynomial matrix with submatrices
Yuni Iwamasa
In this paper, we consider the problem of computing the entire sequence of the maximum degree of minors of a block-structured symbolic matrix (a generic partitioned polynomial matr…
A combinatorial algorithm for computing the rank of a generic partitioned matrix with submatrices
Hiroshi Hirai, Yuni Iwamasa
In this paper, we consider the problem of computing the rank of a block-structured symbolic matrix (a generic partitioned matrix) , where is a $2 \tim…
Optimal matroid bases with intersection constraints: Valuated matroids, M-convex functions, and their applications
Yuni Iwamasa, Kenjiro Takazawa
For two matroids and with the same ground set and two cost functions and on , we consider the problem of finding bases of and of…
Reconstructing phylogenetic trees from multipartite quartet systems
Hiroshi Hirai, Yuni Iwamasa
A phylogenetic tree is a graphical representation of an evolutionary history of taxa in which the leaves correspond to the taxa and the non-leaves correspond to speciations. One of…
A tractable class of binary VCSPs via M-convex intersection
Hiroshi Hirai, Yuni Iwamasa, Kazuo Murota +1
A binary VCSP is a general framework for the minimization problem of a function represented as the sum of unary and binary cost functions. An important line of VCSP research is to…