12 citations · 37 across the 22 of their papers we have counts for
13 papers · 1 filter
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…
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…
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 $\…
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…
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…
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…