Öznur Yaşar Diner

Yaşar Diner, Öznur

Name Variants

Yaşar Diner, Öznur
Yaşar Diner,Ö.
Oznur, Yasar Diner
O. Yaşar Diner
Yasar Diner, Oznur
Y., Öznur
Oznur Yaşar Diner
Yasar Diner,Ö.
Yaşar Diner, Ö.
YAŞAR DINER, ÖZNUR
YAŞAR DINER, Öznur
Y.,Oznur
Yasar Diner,O.
Öznur Yaşar Diner
Yaşar Diner, ÖZNUR
Yaşar Diner, O.
Y., Oznur
Ö. Yaşar Diner
ÖZNUR YAŞAR DINER
Yaşar Diner, Oznur
Yasar Diner,Oznur
Öznur YAŞAR DINER
Diner, Öznur Yaşar
Diner, Oznur Yasar
Diner, Ö.Y.

Job Title

Dr. Öğr. Üyesi

Email Address

oznur.yasar@khas.edu.tr

ORCID ID

0000-0002-9271-2691

Scopus Author ID

58777832500

Full item page

Scholarly Output

17

Articles

9

Citation Count

0

Supervised Theses

1 Scholarly Output Search Results

Now showing 1 - 10 of 17

Citation Count: 6
On list k-coloring convex bipartite graphs
(Springer Nature, 2021) Yaşar Diner, Öznur; Diner, Öznur Yaşar; Serna, Maria; Oriol, Serra
List k-Coloring (Lik-Col) is the decision problem asking if a given graph admits a proper coloring compatible with a given list assignment to its vertices with colors in {1, 2, …, k}. The problem is known to be NP-hard even for k = 3 within the class of 3-regular planar bipartite graphs and for k = 4 within the class of chordal bipartite graphs. In 2015 Huang, Johnson and Paulusma asked for the complexity of Li 3-Col in the class of chordal bipartite graphs. In this paper, we give a partial answer to this question by showing that Lik-Col is polynomial in the class of convex bipartite graphs. We show first that biconvex bipartite graphs admit a multichain ordering, extending the classes of graphs where a polynomial algorithm of Enright et al. (SIAM J Discrete Math 28(4):1675–1685, 2014) can be applied to the problem. We provide a dynamic programming algorithm to solve the Lik-Col in the class of convex bipartite graphs. Finally, we show how our algorithm can be modified to solve the more general LiH-Col problem on convex bipartite graphs.
Citation Count: 1
Block Elimination Distance
(Springer Japan Kk, 2022) Yaşar Diner, Öznur; Giannopoulou, Archontia C.; Stamoulis, Giannos; Thilikos, Dimitrios M.
We introduce the parameter of block elimination distance as a measure of how close a graph is to some particular graph class. Formally, given a graph class g, the class B(G) contains all graphs whose blocks belong to G and the class A(G) contains all graphs where the removal of a vertex creates a graph in G. Given a hereditary graph class G, we recursively define G((k)) so that G((0)) = B(G) and, if k >= 1 G((k)) B(A(G((k-1))) ) N We show that, for every nontrivial hereditary class g, the problem of deciding whether G is an element of G((k)) is NP-complete. We focus on the case where G is minor-closed and we study the minor obstruction set of G((k)) i.e., the minor-minimal graphs not in G((k)). We prove that the size of the obstructions of G((k)) is upper bounded by some explicit function ofk and the maximum size of a minor obstruction of G. This implies that the problem of deciding whether G is an element of G((k)) is constructively fixed parameter tractable, when parameterized by k. Finally, we give two graph operations that generate members of G((k)) from members of G((k -1)) and we prove that this set of operations is complete for the class O of outerplanar graphs.Please check and confirm if the authors Given and Family names have been correctly identified for author znur YaYar Diner. All authors names have been identified conectly. Please confirm if the corresponding author is correctly identified. Amend if necessary.This is correct
Citation Count: 0
On minimum vertex bisection of random d-regular graphs
(Academic Press inc Elsevier Science, 2024) Yaşar Diner, Öznur; Diner, Oznur Yasar; Serna, Maria; Serra, Oriol
Minimum vertex bisection is a graph partitioning problem in which the aim is to find a partition of the vertices into two equal parts that minimizes the number of vertices in one partition set that have a neighbor in the other set. In this work we are interested in providing asymptotically almost surely upper bounds on the minimum vertex bisection of random d -regular graphs, for constant values of d . Our approach is based on analyzing a greedy algorithm by using the differential equation method. In this way, we obtain the first known non -trivial upper bounds for the vertex bisection number in random regular graphs. The numerical approximations of these theoretical bounds are compared with the emprical ones, and with the lower bounds from Kolesnik and Wormald (2014) [30]. (c) 2024 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/).
List Coloring Based Algorithm for the Futoshiki Puzzle
(Ramazan Yaman, 2024) Yaşar Diner, Öznur; Diner, Oznur Yasar
Given a graph G = ( V, E ) and a list of available colors L ( v ) for each vertex v is an element of V , where L ( v ) subset of {1,2, . . . , k }, LIST k-COLORING refers to the problem of assigning colors to the vertices of G so that each vertex receives a color from its own list and no two neighboring vertices receive the same color. The decision version of the problem, LIST k-COLORING, is NP-complete even for bipartite graphs. As an application of list coloring problem we are interested in the Futoshiki Problem. Futoshiki is an NP-complete Latin Square Completion Type Puzzle. Considering Futoshiki puzzle as a constraint satisfaction problem, we first give a list coloring based algorithm for it which is efficient for small boards of fixed size. To thoroughly investigate the efficiency of our algorithm in comparison with a proposed backtracking-based algorithm, we conducted a substantial number of computational experiments at different difficulty levels, considering varying numbers of inequality constraints and given values. Our results from the extensive range of experiments indicate that the list coloring-based algorithm is much more efficient.
Citation Count: 0
The multicolored graph realization problem
(Elsevier B.V., 2022) Yaşar Diner, Öznur; Diner, Ö.Y.; Serna, M.; Serra, O.
We introduce the multicolored graph realization problem (MGR). The input to this problem is a colored graph (G,?), i.e., a graph G together with a coloring ? on its vertices. We associate each colored graph (G,?) with a cluster graph (G?) in which, after collapsing all vertices with the same color to a node, we remove multiple edges and self-loops. A set of vertices S is multicolored when S has exactly one vertex from each color class. The MGR problem is to decide whether there is a multicolored set S so that, after identifying each vertex in S with its color class, G[S] coincides with G?. The MGR problem is related to the well-known class of generalized network problems, most of which are NP-hard, like the generalized Minimum Spanning Tree problem. The MGR is a generalization of the multicolored clique problem, which is known to be W[1]-hard when parameterized by the number of colors. Thus, MGR remains W[1]-hard, when parameterized by the size of the cluster graph. These results imply that the MGR problem is W[1]-hard when parameterized by any graph parameter on G?, among which lies treewidth. Consequently, we look at the instances of the problem in which both the number of color classes and the treewidth of G? are unbounded. We consider three natural such graph classes: chordal graphs, convex bipartite graphs and 2-dimensional grid graphs. We show that MGR is NP-complete when G? is either chordal, biconvex bipartite, complete bipartite or a 2-dimensional grid. Our reductions show that the problem remains hard even when the maximum number of vertices in a color class is 3. In the case of the grid, the hardness holds even for graphs with bounded degree. We provide a complexity dichotomy with respect to cluster size. © 2022 The Author(s)
Citation Count: 5
Three-fast-searchable graphs
(Elsevier Science Bv, 2013) Yaşar Diner, Öznur; Diner, Öznur Yaşar; Dyer, Danny
In the edge searching problem searchers move from vertex to vertex in a graph to capture an invisible fast intruder that may occupy either vertices or edges. Fast searching is a monotonic internal model in which at every move a new edge of the graph G must be guaranteed to be free of the intruder. That is once all searchers are placed the graph G is cleared in exactly vertical bar E(G)vertical bar moves. Such a restriction obviously necessitates a larger number of searchers. We examine this model and characterize graphs for which 2 or 3 searchers are sufficient. We prove that the corresponding decision problem is NP-complete. (C) 2013 Elsevier B.V. All rights reserved.
Citation Count: 0
Searching circulant graphs
(2011) Yaşar Diner, Öznur; Dyer, Danny
[Abstract Not Available]
Citation Count: 11
Strategic Early Warning System for the French milk market: A graph theoretical approach to foresee volatility
(Elsevier, 2017) A. Bısson, Chrıstophe Louıs; Yaşar Diner, Öznur
This paper presents a new approach for developing a Strategic Early Warning System aiming to better detect and interpret weak signals. We chose the milk market as a case study in line with the recent call from the EU Commission for governance tools which help to better address such highly volatile markets. Furthermore on the first of April 2015 the new Common Agricultural Policy ended quotas for milk which led to a milk crisis in the EU. Thus we collaborated with milk experts to get their inputs for a new model to analyse the competitive environment. Consequently we constructed graphs to represent the major factors that affect the milk industry and the relationships between them. We obtained several network measures for this social network such as centrality and density. Some factors appear to have the largest major influence on all the other graph elements while others strongly interact in cliques. Any detected changes in any of these factors will automatically impact the others. Therefore scanning ones competitive environment can allow an organisation to get an early warning to help it avoid an issue (as much as possible) and/or seize an opportunity before its competitors. We conclude that Strategic Early Warning Systems as a corporate foresight approach utilising graph theory can strengthen the governance of markets. (C) 2017 Elsevier Ltd. All rights reserved.
Citation Count: 0
The multicolored graph realization problem
(Elsevier, 2024) Yaşar Diner, Öznur; Diner, Oznur Yasar; Serna, Maria; Serra, Oriol
We introduce the multicolored graph realization problem (MGR). The input to this problem is a colored graph ( G , phi ), i.e., a graph G together with a coloring phi on its vertices. We associate each colored graph ( G , phi ) with a cluster graph ( G phi ) in which, after collapsing all vertices with the same color to a node, we remove multiple edges and self -loops. A set of vertices S is multicolored when S has exactly one vertex from each color class. The MGR problem is to decide whether there is a multicolored set S so that, after identifying each vertex in S with its color class, G [ S ] coincides with G phi . The MGR problem is related to the well-known class of generalized network problems, most of which are NP -hard, like the generalized Minimum Spanning Tree problem. The MGR is a generalization of the multicolored clique problem, which is known to be W [ 1 ] -hard when parameterized by the number of colors. Thus, MGR remains W [ 1 ] - hard, when parameterized by the size of the cluster graph. These results imply that the MGR problem is W [ 1 ] -hard when parameterized by any graph parameter on G phi , among which lies treewidth. Consequently, we look at the instances of the problem in which both the number of color classes and the treewidth of G phi are unbounded. We consider three natural such graph classes: chordal graphs, convex bipartite graphs and 2 -dimensional grid graphs. We show that MGR is NP -complete when G phi is either chordal, biconvex bipartite, complete bipartite or a 2 -dimensional grid. Our reductions show that the problem remains hard even when the maximum number of vertices in a color class is 3. In the case of the grid, the hardness holds even for graphs with bounded degree. We provide a complexity dichotomy with respect to cluster size. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Computational complexity of list coloring and ıts variants for particular graph classes
(2023) Yaşar Diner, Öznur; Diner, Öznur Yaşar
Her bir 𝑣 ∈ 𝑉 düğümü için bir 𝐺 = (𝑉, 𝐸) çizgesi ve her bir düğüme atanan mevcut renklerin bir listesi 𝐿(𝑣) verilmiştir. Burada Liste 3-Renklendirme problemi her düğümün 𝐿(𝑣) ⊆ {1, 2, . . . , 𝑘}, kendi listesinden bir renk aldığı ve 𝐺'deki hiçbir iki komşu düğümün aynı rengi alamadığı renk atama problemini ifade eder. Liste 3-Renklendirme probleminin karar versiyonu, iki parçalı çizgeler için NP-Tamdır ve tarak dışbükey iki parçalı çizgelerdeki karmaşıklığı açık bir problemdir. Bu tezde Liste 3-Renklendirme problemini tarak dışbükey iki parçalı çizgelerin süper sınıfı olan tırtıl dışbükey iki parçalı çizgelere indirgeyen polinom zamanlı bir algoritma veriyoruz. Tanıma algoritmaları verimli algoritmaların tasarlanmasında çok önemli bir yer tutar. İki parçalı çizgeler gibi birçok çizge sınıfını tanımak ve bir çizgenin uygun temsilini üretmek için iyi bilinen algoritmalar vardır. Burada tırtıl dış bükey iki parçalı çizge sınıfı için bir polinom zamanlı tanıma algoritması ve bu çizgeye karşılık gelen bir tırtıl temsili veriyoruz. Bu algoritma değiştirilerek, tarak dışbükey iki parçalı çizgelerin için bir polinom zamanlı tanıma algoritması verildi. Liste 3-Renklendirme ve tanıma algoritmalarının yanında Liste renklendirme probleminin bir uygulaması olan Futoshiki Problemi ile ilgileniyoruz. Futoshiki, bir NP-Tam Latin Kare Tamamlama Tipi Bulmacasıdır. Futoshiki bulmacasını bir koşul tatmin problemi olarak ele aldığımızda, öncelikle buna yönelik bir liste renklendirme tabanlı algoritma veriyoruz. Ayrıca, geliştirdiğimiz algoritmanın performansını gerçekleştirdiğimiz deneylerden elde ettiğimiz sonuçlarla karşılaştırmak için iki deterministik algoritma daha sunuyoruz. Son olarak, Minimum Çatışma Algoritması, Karınca Kolonisi Optimizasyon Algoritması ve Genetik Algoritmayı içeren üç stokastik algoritma veriyoruz.