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Conference Object Citation - WoS: 13Search-Based Parallel Refactoring Using Population-Based Direct Approaches(Springer-verlag Berlin, 2011) Kilic, Hurevren; Koc, Ekin; Cereci, IbrahimAutomated software refactoring is known to be one of the "hard" combinatorial optimization problems of the search-based software engineering field. The difficulty is mainly due to candidate solution representation, objective function description and necessity of functional behavior preservation of software. The problem is formulated as a combinatorial optimization problem whose objective function is characterized by an aggregate of object-oriented metrics or pareto-front solution description. In our recent empirical study, we have reported the results of a comparison among alternative search algorithms applied for the same problem: pure random, steepest descent, multiple first descent, simulated annealing, multiple steepest descent and artificial bee colony searches. The main goal of the study was to investigate potential of alternative multiple and population-based search techniques. The results showed that multiple steepest descent and artificial bee colony algorithms were most suitable two approaches for an efficient solution of the problem. An important observation was either with depth-oriented multiple steepest descent or breadth-oriented population-based artficial bee colony searches, better results could be obtained through higher number of executions supported by a lightweight solution representation. On the other hand different from multiple steepest descent search, population-based, scalable and being suitable for parallel execution characteristics of artificial bee colony search made the population-based choices to be the topic of this empirical study. I In this study, we report the search-based parallel refactoring results of an empirical comparative study among three population-based search techniques namely, artificial bee colony search, local beam search and stochastic beam search and a non-populated technique multiple steepest descent as the baseline. For our purpose, we used parallel features of our prototype automated refactoring tool A-CMA written in Java language. A-CMA accepts bytecode compiled Java codes as its input. It supports 20 different refactoring actions that realize searches on design landscape defined by an adhoc quality model being an aggregation of 24 object-oriented software metrics. We experimented 6 input programs written in Java where 5 of them being open source codes and one student project code. The empirical results showed that for almost all of the considered input programs with different run parameter settings, local beam search is the most suitable population-based search technique for the efficient solution of the search-based parallel refactoring problem in terms of mean and maximum normalized quality gain. However, we observed that the computational time requirement for local beam search becomes rather high when the beam size exceeds 60. On the other hand, even though it is not able to identify high quality designs for less populated search setups, time-efficiency and scalability properties of artificial bee colony search makes it a good choice for population sizes >= 200.Conference Object F-Actor: a Multiagent Gaming Environment for Controlling Virtual Flow Networks(Univ Wolverhampton, 2008) Ocal, Ilter Kagan; Cevik, Ahmet; Cereci, Ibrahim; Kilic, Hurevren; Computer EngineeringA gaming environment that enables agent-based local control of a configurable virtual flow network is developed. The gaming software what we call F-Actor provides a graph-based discrete virtual control environment on which user-developed controller agents reside and act according to their assigned design goals. Runtime performances of user-developed controller agent codes are made observable through a graphical user interface. The proposed game can be played by different developers having different level of control and programming knowledge. By playing with F-Actor, engineers (or students) can make practices on a virtual flow environment and try alternative intelligent control algorithms before their potential implementations on field.Conference Object An Investigation About Process Matchmaking Performances of Unstructured and Decentralized Digital Environments(Ieee, 2007) Cakir, Bugra; Kilic, HurevrenEfficient matchmaking is an important problem in unstructured and decentralized digital environments. We report the results of simulations of these environments and provide measurements of match performance focusing on unstructured and decentralized environments. In the study, different environment models including P2P (Hypergrid, Gnutella with/without ultrapeer); small-world (Watts-Strogatz); heavy-tailed and random versions of Autonomous System Waxman model showing power-law distribution property; random and 2D-Grid are considered. The flooding mechanism enabling process encounters for match purposes is uninformed Breadth-First-Search. Simulations show that the matchmaking performance of random environment outperforms the others for almost all different problems and time-to-live settings. On the other hand, the total cost of small world environment model is the highest for almost all setups.Conference Object Citation - WoS: 2CAWP A Combinatorial Auction Web Platform(Scitepress, 2010) Cereci, Ibrahim; Kilic, HurevrenOnline auctions, including online Combinatorial Auctions, are important examples of e-commerce applications. In this paper, a Combinatorial Auction Web Platform (CAWP) is introduced. The platform enables both product selling and buying capabilities that can be realized in a combinatorial way. CAWP supports a Sealed-Bid Single-Unit type of Combinatorial Auctions. Easy customization for any selected problem domain is a distinguished feature of CAWP. Platform users are not expected to have any technical knowledge about how to solve the Winner Determination Problem (WDP) known to be critical for profit maximization of the auctioneers in Combinatorial Auctions.Article Citation - WoS: 4Citation - Scopus: 6An Automata Networks Based Preprocessing Technique for Artificial Neural Network Modelling of Primary Production Levels in Reservoirs(Elsevier, 2007) Kilic, Hurevren; Soyupak, Selcuk; Tuzun, Ilhami; Ince, Ozlem; Basaran, GokbenPrimary production in lakes and reservoirs develops as a result of complex reactions and interactions. Artificial neural networks (ANN) emerges as an approach in quantification of primary productivity in reservoirs. Almost all of the past ANN applications employed input data matrices whose vectors represent either water quality parameters or environmental characteristics. Most of the time, the components of input matrices are determined using expert opinion that implies possible factors that affect output vector. Major disadvantage of this approach is the possibility of ending-up with an input matrix that may have high correlations between some of its components. In this paper, an automata networks (AN) based preprocessing technique was developed to select suitable and appropriate constituents of input matrix to eliminate redundancy and to enhance calculation efficiency. The proposed technique specifically provides an apriori rough behavioral modeling through identification of minimal AN interaction topology. Predictive ANN models of primary production levels were developed for a reservoir following AN based pre-modeling step. The achieved levels of model precisions and performances were acceptable: the calculated root mean square error values (RMSE) were low; a correlation coefficient (R) as high as 0.83 was achieved with an ANN model of a specific structure. (c) 2006 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 3An Agent-based Trading Infrastructure for Combinatorial Reverse Auctions(Ieee, 2014) Bayindir, Hakan; Kilic, Hurevren; Rehan, MohammedA Combinatorial Reverse Auction Trading Infrastructure - CRATI is designed and implemented as an agent-based system. Two basic building blocks Java Agent Development Framework (JADE) and an Open Source Java Constraint Programming Library (Choco Solver) are used to facilitate agent interactions and an optimization task. For our purpose, it is shown that auction Winner Determination Problem (WDP) can suitably be represented as a weighted set covering problem instance whose solution gives the decided winners of the auction process. In order to realize the system, a variation of Contract Net protocol is designed and implemented to handle auctions that occur in the platform from start to finish.Article Citation - WoS: 1Citation - Scopus: 2Promotion of Cooperation in a Co-Evolutionary Pragmatic Agent Multigame Environment(Elsevier, 2025) Kilic, Omer Durukan; Kilic, HurevrenThe promotion of cooperation in a co-evolutionary environment where pragmatic agents participate in a multigame setting that contains Prisoner's Dilemma (PD) and SnowDrift (SD) games is investigated. The pragmatic agent conserves its current perspective when successful; otherwise adopts the opposite perspective. Unlike traditional models, this study introduces a setup in which perception and strategy spaces co-evolve in terms of iterative game payoffs. The players are situated in a 2-D square lattice environment and synchronously update their perceptions and strategies after interacting with their immediate neighbors. The ratios of perceptions and strategy are randomly set based on parameters alpha and /3, indicating initial SD and cooperation (C) percentages, respectively. By the end of various simulations, the system's convergent and stable behavior is shown by means, standard deviations, and confidence intervals. The results show that larger (alpha >= 0.5) initial populations of SD agents promote greater cooperation and lead to a dominance of cooperative strategies even for smaller initial C strategies (/3 similar to 0.2). Conversely, when the environment is initially dominated by PD perspectives and defect (D) strategies (alpha = 0.1, /3 = 0.2), it leads to lower levels of cooperation. Depending on the initial ratios of PD/SD and D/C players, cooperative player clusters are not only formed but are also persistent parts of the environment. Finally, we observed that co-evolving PD/SD and D/C environments coupled with pragmatic players lead to a controllable promotion of cooperation even against small initial SD player ratios.Conference Object Mobile Prisoner's Dilemma Game Played on Diverse Habitats(Ieee, 2011) Celebi, Remzi; Kilic, HurevrenPromotion of cooperative behavior in Prisoner's Dilemma (PD) game while players that are allowed to move between different gaming environments (i.e. habitats) is investigated. The stochastic mobile model under study is realized over connected habitats that are situated on a two dimensional grid environment. The players appearing in the same habitat are allowed to interact with their immediate neighbors. Mobility of a player is defined as movement from its habitat to another based on both obtained payoff and randomly assigned habitat diversity values. By the end of extensive experimentation, it is concluded that player mobility is an effective factor that contributes to promotion of cooperation in spatial evolutionary games. Also, even for higher values of temptation of PD game, habitat diversity supports and triggers a collective resistance for the emergence and promotion of cooperative system behavior.Conference Object Citation - WoS: 6Citation - Scopus: 7Protocol and Connectivity Based Overlay Level Capacity Calculation of P2p Networks(Ieee Computer Soc, 2006) Oztoprak, Kasim; Kilic, HurevrenIn this paper, we proposed a metric for P2P networks based on Shannon's L-channel capacity calculation idea. The metric calculates the maximum rate of information (in bits per second) that can be transmitted over P2P network (a.k.a. combinatorial capacity) caused by protocol and overlay-level connectivity. We suggest P2P systems to be modeled as a discrete noiseless channel on which the protocol together with dynamically changing overlay-level instant connectivity topology defines a Shannon Language. In experimental works, we applied the metric first to the Gnutella 0.6 protocol for which message traffic explosion is a known problem and then to its time-based clustering version. The obtained results are compared with other two known metrics' namely, number of query hits and unit query-hit response time, results and potential correlations among them are discussed.Article Citation - WoS: 3Citation - Scopus: 3Online Learning Perceptions Amid Covid-19 Pandemic: the Engineering Undergraduates' Perspective(Tempus Publications, 2022) Eryilmaz, Meltem; Kalem, Guler; Kilic, Hurevren; Tirkes, Guzin; Topalli, Damla; Turhan, Cigdem; Yazici, Ali; Information Systems Engineering; Computer Engineering; Software EngineeringThe COVID-19 pandemic caused face-to-face education in just about all universities worldwide to shift to online education. For most students, this educational model was a compulsory first experience. In this study, the survey results are analyzed and discussed related to a group of students in the Engineering Faculty of a university in Turkey regarding their online education perceptions. Briefly summarized, the findings of the study indicate that: (a) most of the students still prefer face-to-face learning, which is also favored if accompanied by distance learning; (b) the concentration level of the students has dropped due to the concerns about the COVID-19 pandemic which affects their learning negatively; and (c) around half of the students participating in the study feel that the online exams conducted without a secure exam software, is considered unsafe. Additionally, the study's results were further extended to evaluate the questionnaire results and reported along with the suggestions of necessary actions in emergency online learning (EOL).
