Çavdaroğlu, Burak

Çavdaroğlu, Burak

Name Variants

Çavdaroğlu, Burak
B.,Çavdaroğlu
B. Çavdaroğlu
Burak, Çavdaroğlu
Cavdaroglu, Burak
B.,Cavdaroglu
B. Cavdaroglu
Burak, Cavdaroglu
Çavdaroğlu, B.

Job Title

Dr. Öğr. Üyesi

Email Address

Burak.cavdaroglu@khas.edu.tr

Full item page

Scholarly Output

8

Articles

4

Citation Count

0

Supervised Theses

3 Scholarly Output Search Results

Now showing 1 - 8 of 8

Citation Count: 1
Round-robin scheduling with regard to rest differences
(Springer, 2023) Tuffaha, Tasbih; Cavdaroglu, Burak; Atan, Tankut
Fairness is a key consideration in designing sports schedules. When two teams play against each other, it is only fair to let them rest the same amount of time before their game. In this study, we aim to reduce, if not eliminate, the difference between the rest durations of opposing teams in each game of a round-robin tournament. The rest difference problem proposed here constructs a timetable that determines both the round and the matchday of each game such that the total rest difference throughout the tournament is minimized. We provide a mixed-integer programming formulation and a matheuristic algorithm that tackle the rest difference problem. Moreover, we develop a polynomial-time exact algorithm for some special cases of the problem. This algorithm finds optimal schedules with zero total rest difference when the number of teams is a positive-integer power of 2 and the number of games in each day is even. Some theoretical results regarding tournaments with one-game matchdays are also presented.
Debris Removal Strategies To Improve Accessibility Road Networks
(Kadir Has Üniversitesi, 2019) Özkenar, Tuğçe; Çavdaroğlu, Burak
Disasters are non-routine events which have occurred in every age of history and have resulted in losses of several lives and economic losses. Debris is one of the most devastating consequence of the disasters. Debris occurs by the collapse of buildings and roads, threatens life, causes environmental problems and interrupts daily life. It is very crucial to remove debris effectively to open blocked roads, reach affected areas and help the people in need. Debris removal operations require a rational decision making process. This thesis focuses debris clearance on the response stage of the disaster management. It is assumed that debris will shut down the roads and prevent the travel of emergency aid teams from reaching people in need. The aim of the dynamic spanning tee (DST) problem introduced in the thesis is to determine the sequence of blocked roads to be cleaned in order to increase the accessibility of the affected areas. The optimization model developed is a mixed integer programming model which is based on an efficient LP formulation of the minimum spanning tree problem. We develop four heuristic methods for the DST problem. With different damage scenarios for a small hypothetical network, the performances of these heuristic methods are compared with the exact optimal solutions. It has been observed that two heuristic methods give the closest results to the optimal solutions. The exact and heuristic methods are also tested on two realistic data sets representing the road networks of Güven and Şirinevler neighborhoods in ˙Istanbul. Due to the large number of variables in the model, commercial solver experiences memory issues in these network instances. It has been shown that the same two heuristic methods performing best in hypothetical instance also give the best results in these data sets. Keywords: Disaster, Debris, Minimum spanning tree (MST)
Detection of Fraudulent Activities in Mobile Display Advertising
(Kadir Has Üniversitesi, 2017) Kaya, Safiye Şeyma; Çavdaroğlu, Burak
Most of the marketing expenditures in mobile advertising are conducted through realtime bidding (RTB) marketplaces in which ad spaces of the sellers (publishers) are auctioned for the impression of the buyers’ (advertisers) mobile apps. One of the most popular cost models in RTB marketplaces is cost per install (CPi). in a CPi campaign publishers place mobile ads of the highest bidders in their mobile apps and are paid by advertisers only if the advertised app is installed by a user. CPi cost model causes some publishers to conduct some infamous fraudulent activities known as click spamming and click injection. A click spamming publisher executes clicks for lots of users who haven’t made them. if one of these users hears about the advertised app organically (say via TV commercial) and installs it this installation will be attributed to the click spamming publisher. in click injection the fraudulent publisher’s spy app monitors the user’s activities in the app market to detect when a mobile app is downloaded on her device and triggers a click attributed to the fraudster right before the installation completes. in this study we propose a novel multiple testing procedure which can identify click spamming and click injection activities using the data of click-to-install time (CTiT) the time difference between the click of a mobile app’s ad and the first launch of the app after the installation. in a sample set of publishers we show that our procedure has a falsepositive error rate of at most 5%. Finally we run an experiment with 15263 publishers. According to the results of the experiment a total of 1474 fraudulent publishers are successfully detected.
The Rest Difference Problem in Round-Robin Tournaments
(Kadir Has Üniversitesi, 2022-01) Tuffaha, Tasbih; Çavdaroğlu, Burak
Fairness is a key consideration in designing tournament schedules. When two teams play against each other, it is only fair to let them rest the same amount of time before their game. In this study, we aim to reduce, if not eliminate, the difference between the rest durations of opposing teams in each game of a round-robin tournament. The rest difference problem proposed in this study constructs a timetable that determines both the round and the matchday of each game such that the total rest difference throughout the tournament is minimized. We provide a mixed-integer programming formulation and a matheuristic algorithm that solve the problem. Moreover, we de velop a polynomial-time exact algorithm for some special cases of the problem. This algorithm finds optimal schedules with zero total rest difference when the number of teams is a positive-integer power of 2 and the number of games in each day is even. Some theoretical results regarding tournaments with one-game matchdays are also provided.
Citation Count: 8
Determining Matchdays in Sports League Schedules To Minimize Rest Differences
(ELSEVIER, 2020) Çavdaroğlu, Burak; Atan, Tankut
Many sports leagues first announce the games to be played in each round and then determine their matchdays as the season progresses. This study focuses on the fairness criterion of minimizing the total rest difference among opposing teams to find the matchdays for an announced schedule. We show that the problem is decomposable into optimizing the rounds separately. We also provide a polynomial-time exact algorithm for canonical schedules.
Citation Count: 13
Minimization of Rest Mismatches in Round Robin Tournaments
(Pergamon-Elsevier Science Ltd, 2018) Atan, Tankut; Çavdaroğlu, Burak
In sports tournaments an occurrence of a difference in the rest periods of opponent teams in a game which we refer to as a rest mismatch will disadvantage the less rested team. Thus it is only fair to expect opposing teams to have rested equally before their game. In this work we introduce and study the Rest Mismatch Problem where the goal is to minimize the number of rest mismatches in a round robin tournament. Two integer linear formulations and a constraint programming formulation are provided and their computational performances are compared for several problem instances. Moreover a heuristic algorithm is developed which finds a single round robin schedule with zero mismatches when the number of teams in the tournament is a multiple of 8 and four mismatches when it is a multiple of 4 but not 8. (C) 2018 Elsevier Ltd. All rights reserved.
Citation Count: 1
Detection of Click Spamming in Mobile Advertising
(Springer Science and Business Media B.V., 2020) Kaya, S.Ş.; Çavdaroğlu, B.; Şensoy, K.S.
Most of the marketing expenditures in mobile advertising are conducted through real-time bidding (RTB) marketplaces, in which ad spaces of the sellers (publishers) are auctioned for the impression of the buyers’ (advertisers) mobile apps. One of the most popular pricing models in RTB marketplaces is cost-per-install (CPI). In a CPI campaign, publishers place mobile ads of the highest bidders in their mobile apps and are paid by advertisers only if the advertised app is installed by a user. CPI pricing model causes some publishers to conduct an infamous fraudulent activity, known as click spamming. A click spamming publisher executes clicks for lots of users who have not authentically made them. If one of these users hears about the advertised app organically (say, via TV commercial) afterwards and installs it, this install will be attributed to the click spamming publisher. In this study, we propose a novel multiple testing procedure which can identify click spamming activities using the data of click-to-install time (CTIT), the time difference between the click of a mobile app’s ad and the first launch of the app after the install. We statistically show that our procedure has a false-positive error rate of 5% in the worst case. Finally, we run an experiment with 30 publishers, half of which are fraudulent. According to the results of the experiment, all non-fraudulent publishers are correctly identified and 73% of the fraudulent publishers are successfully detected. © 2020, Springer Nature Switzerland AG.
Citation Count: 1
Integrated Break and Carryover Effect Minimization
(Springer, 2022) Cavdaroglu, Burak; Atan, Tankut
A fair schedule helps in improving the competitiveness and attractiveness of sports tournaments and in turn contributes positively to the sports economy. Break minimization and carryover effects minimization are considered to be two important criteria of fairness in scheduling of compact round-robin tournaments, and most related research looks at these problems separately. Various studies have sought to minimize the carryover effects in tournaments so that the number of breaks per team does not exceed a specific level. This study, however, is the first effort to define an integrated problem that aims to minimize the carryover effects and the number of breaks simultaneously for round-robin tournaments. We first introduce the mathematical formulation for the problem, whose objective measures how well a schedule simultaneously performs with respect to the number of breaks and the carryover effects. We then develop a heuristic method for this computationally hard problem. Comparing our results with the previous literature and the current practices of some European leagues, we show that our method provides schedules with better objective function values.