Serhat Dogan - Academia.edu (original) (raw)
Papers by Serhat Dogan
Operations Research
Dogan and Yildiz introduce and analyze the pro-con model that is inspired by Franklin’s prudentia... more Dogan and Yildiz introduce and analyze the pro-con model that is inspired by Franklin’s prudential algebra. Consider an agent who is endowed with two sets of orderings: pro- and con-orderings. For each choice set, if an alternative is the top-ranked by a pro-ordering (con-ordering), then this is a pro (con) for choosing that alternative. The alternative with more pros than cons is chosen from each choice set. Each ordering may have a weight reflecting its salience. In this case, the probability that an alternative is chosen equals the difference between the total weights of its pros and cons. Although, this is an additive model similar to the random utility model with structurally invariant primitives, authors show that every (random) choice function is (random) pro-con rational. Their technique requires a generalization of Ford-Fulkerson theorem. The connection between the random model and its deterministic counterpart demonstrates a fruitful use of classical integer programming te...
METU Studies in Development, 2020
In a standard tug-of-war model, two players engage in a component battle each period and a player... more In a standard tug-of-war model, two players engage in a component battle each period and a player wins the contest if her number of battle victories exceeds the other contestant’s by a certain number. In this paper, we introduce a multi-player model of intra-group tug-of-war played by two groups of two players, where a player wins the contest if she wins a certain number of battles more than the other player from her group before either player from the other group achieves the same against one another. We characterize the unique subgame perfect Nash equilibrium of the model and further analyze an asymmetric case with different number of players in the competing groups. Our results indicate an extreme discouragement effect for the laggards and a strong momentum effect for the winner of the first battle.
SSRN Electronic Journal, 2020
We present a new choice model. An agent is endowed with two sets of preferences: pro-preferences ... more We present a new choice model. An agent is endowed with two sets of preferences: pro-preferences and con-preferences. For each choice set, if an alternative is the best (worst) for a pro-preference (con-preference), then this is a pro (con) for choosing that alternative. The alternative with more pros than cons is chosen from each choice set. Each preference may have a weight reflecting its salience. In this case, the probability that an alternative is chosen equals the difference between the weights of its pros and cons. We show that this model provides a unified lens through which every nuance of the rich human choice behavior can be structurally explained. ∗We are grateful to Ariel Rubinstein, Efe Ok, Yusufcan Masatlioglu, Erkut Ozbay, Ed Green, Kfir Eliaz, Mustafa Celebi Pinar, Ran Spiegler, Burak Pac, Paola Manzini, Marco Mariotti, Michael Richter, Battal Dogan, Selman Erol, Faruk Gul, Wolfgang Pesendorfer, Leeat Yariv, David Dillenberger, Pietro Ortoleva, and seminar participa...
In this short paper we propose a preference based extension of the Luce rule, and show that it is... more In this short paper we propose a preference based extension of the Luce rule, and show that it is the only random choice rule that satisfies rejection likelihood additivity. Luce rule asserts that each alternative has a fixed positive weight and from each choice set the probability that an alternative is chosen equals to its relative weight in the given choice set. 1 Since the weight that is assigned to each alternative is positive and there is no ranking of these alternatives, each alternative is chosen from each choice set with positive probability.2 On the other hand, for a decision maker or a group of decision makers, an alternative may clearly dominate the other, therefore from some choice sets some alternatives may not be chosen at all. Motivated with ∗We are grateful to Ariel Rubinstein, Faruk Gul, Efe Ok, and Battal Dogan, seminar participants at Tel Aviv University, NYU, and Bilkent University for their helpful comments. †Bilkent University, Department of Economics. ‡Bilken...
SSRN Electronic Journal, 2020
Journal of Turgut Ozal Medical Center, 2017
Mathematical Social Sciences, 2021
We study bribing in a sequential team contest with multiple pairwise battles. We allow for asymme... more We study bribing in a sequential team contest with multiple pairwise battles. We allow for asymmetries in winning prizes and marginal costs of effort; and we characterize the conditions under which (i) a player in a team is offered a bribe by the owner of the other team and (ii) she accepts the bribe. We show that these conditions depend on the ratios of players' winning prizes and marginal costs of effort: the team owner chooses to bribe the player with the most favorable winning prize to marginal cost of effort ratio, and offer a bribe that leaves her indifferent between accepting (and exerting zero effort) and not accepting (and exerting her optimal effort). In some cases, the competition between players and the negative consequences of one player receiving a bribe on the team performance can drag down equilibrium bribe to zero. We also study the impact of changes in winning prizes and marginal costs of effort on equilibrium bribing behavior.
Journal of Economics & Management Strategy, 2020
We consider a network of heterogeneous agents where each edge represents a two-player contest bet... more We consider a network of heterogeneous agents where each edge represents a two-player contest between the respective nodes. In these bilateral contests, agents compete over an endogenous prize jointly produced using their own contest efforts. We provide a necessary and sufficient condition for the existence of Nash equilibrium and characterize the equilibrium total effort for every agent. Our model has insightful results regarding the network type, that is, depending on whether the network is bipartite or nonbipartite. Finally, considering the sum of all expected utilities as an efficiency notion, we investigate the optimal network structure.
SSRN Electronic Journal, 2017
A new choice model is presented. An agent is endowed with two sets preferences: pro-preferences a... more A new choice model is presented. An agent is endowed with two sets preferences: pro-preferences and con-preferences. For each choice set, if an alternative is the best (worst) for a pro-preference (con-preference), then this is a pro (con) for choosing that alternative. The alternative that has more pros than cons is chosen from each choice set. Each preference may have a weight reflecting its salience. In this case, each alternative is chosen with a probability proportional to the difference between the weights of its pros and cons. We show that this model accommodates every choice behavior. JEL Classification Numbers: D01
Selcuk Tip Dergisi, 2019
Kırk bir yaşında kadın ve 64 yaşında bir erkek hasta karın ağrısı nedeniyle kliniğimize başvurdu.... more Kırk bir yaşında kadın ve 64 yaşında bir erkek hasta karın ağrısı nedeniyle kliniğimize başvurdu. Yapılan tetkiklerinde her iki vakada da karaciğerde dev hemanjiom olduğu raporlandı. Her iki vakada semptomatik olması ve malignite şüphesi olması nedeniyle operasyon kararı alındı. Operasyon esnasında kitlenin karaciğer kaynaklı olmadığı, sağ sürrenal kaynaklı dev adenom olduğu görüldü, ikinci vakada da kitlenin sağ böbrek kaynaklı olduğu görüldü. Rezeksiyon yapıldı. Sürrenal bölgedeki kitlelerin hemanjiomlarla karıştırılabileceği unutulmamalıdır.
SSRN Electronic Journal, 2018
We present a characterization of the Luce rule in terms of positivity and a new choice axiom call... more We present a characterization of the Luce rule in terms of positivity and a new choice axiom called odds supermodularity that strengthens the regularity axiom. This new characterization illuminates a connection that goes unnoticed, and sheds light on the behavioral underpinnings of the Luce rule and its extensions from a different perspective. We also show that odds supermodularity per se characterizes a structured extension of the Luce rule that accommodates zero probability choices.
Public Choice, 2019
In the contest literature, sabotage is defined as a deliberate and costly activity that damages t... more In the contest literature, sabotage is defined as a deliberate and costly activity that damages the opponent's likelihood of winning the contest. Most of the existing results suggest that, anticipating a possible sabotage, contestants would be discouraged from exerting high efforts. In this paper we investigate the act of sabotage in a team contest wherein team members exert costly efforts as a contribution to their team's aggregate effort, which in turn determines the contest's outcome. For the baseline model with no sabotage, there exists a corner equilibrium implying a free-rider problem in each team. As for the model with sabotage, our characterization of Nash equilibrium reveals two important results: (i) a unique interior equilibrium exists so that the free-rider problem no longer is a concern and (ii) the discouragement effect of sabotage vanishes for some players. On top of those conclusions, we investigate the team owner's problems of prize allocation and team formation with the objective being to maximize his team's winning probability.
Journal of Economic Behavior & Organization, 2018
We present a model of race with multiple players and study players' effort choices and expected p... more We present a model of race with multiple players and study players' effort choices and expected prizes in equilibrium. We show that, in equilibrium, once any two players win one battle each, the remaining players do not exert any effort anymore. This turns the continuation game into a two-player race. This is different than the results in previous two-player models of race, which report that all states of the game are reached with positive probabilities. We also provide a set of comparative static results on the effects of the number of players and the victory threshold.
Annals of Medical Research, 2018
First cadaveric kidney transplant was performed in 1933 in Russia by Voronoy (1,2). Renal failure... more First cadaveric kidney transplant was performed in 1933 in Russia by Voronoy (1,2). Renal failure is treated with renal transplantation. After renal transplantation (tx) rate of urinary complications are 5-12.5%. Double-j ureteral stents was developed by Finney in 1978 (3). After renal transplantation double J catheter-related urinary complications are quite rare. Our aim is, in this study we explain ureteral necrosis, and double J catheter was distortion and anastomotic leakage of urine in renal transplant patient.
SSRN Electronic Journal, 2017
A (capacity-constrained) choice problem consists of a set of alternatives and a capacity. A (capa... more A (capacity-constrained) choice problem consists of a set of alternatives and a capacity. A (capacity-constrained) choice rule, at each choice problem, chooses from the alternatives without exceeding the capacity. A choice rule is lexicographic if there exists a list of priority orderings over potential alternatives such that at each choice problem, the set of chosen alternatives is obtainable by choosing the highest ranked alternative according to the first priority ordering, then choosing the highest ranked alternative among the remaining alternatives according to the second priority ordering, and proceeding similarly until the capacity is full or no alternative is left. Lexicographic choice rules have been useful in designing allocation mechanisms for school choice to achieve diversity. We provide a characterization of lexicographic choice rules. We discuss some implications for the Boston school choice system. We also provide a characterization of deferred acceptance mechanisms that operate based on a lexicographic choice structure.
SSRN Electronic Journal, 2016
We introduce and analyze an efficiency criterion for probabilistic assignment of objects, when on... more We introduce and analyze an efficiency criterion for probabilistic assignment of objects, when only ordinal preference information is available. This efficiency criterion is based on the following domination relation: a probabilistic assignment dominates another assignment if it is ex-ante efficient for a strictly larger set of utility profiles consistent with the ordinal preferences. We provide a simple characterization of this domination relation. We revisit an extensively studied assignment mechanism, the Probabilistic Serial mechanism (Bogomolnaia and Moulin, 2001), which always chooses a "fair" assignment. We show that the Probabilistic Serial assignment may be dominated by another fair assignment. We provide conditions under which the serial assignment is undominated among fair assignments.
SSRN Electronic Journal, 2017
Each acceptant and substitutable choice rule is known to have a maximizer-collecting representati... more Each acceptant and substitutable choice rule is known to have a maximizer-collecting representation: there exists a list of priority orderings such that from each choice set that includes more elements than the capacity, the choice is the union of the priority orderings' maximizers (Aizerman and Malishevski, 1981). We introduce the notion of a prime atom and constructively prove that the number of prime atoms of a choice rule determines its smallest size maximizer-collecting representation. We show that responsive choice rules require the maximal number of priority orderings in their maximizer-collecting representations among all acceptant and substitutable choice rules. We characterize maximizer-collecting choice rules in which the number of priorities equals the capacity. We also show that if the capacity is greater than three and the number of elements exceeds the capacity by at least two, then no acceptant and substitutable choice rule has a maximizer-collecting representation of the size equal to the capacity.
Archives of Medical Science - Civilization Diseases, 2017
Surgical laparoscopy, endoscopy & percutaneous techniques, Jan 3, 2015
Laparoscopic cholecystectomy (LC) now has become the golden standard in the treatment of symptoma... more Laparoscopic cholecystectomy (LC) now has become the golden standard in the treatment of symptomatic gallstone cholecystitis. This retrospective analysis was conducted to clarify the reasons of early return to the hospital after discharge following a procedure like LC that has been frequently performed in daily surgical practice. This study covers 586 patients, who were called to follow-ups and thus evaluated, of 676 patients who had had LCs at Meram Medical School's General Surgery Clinic between January 2010 and May 2011. The rate of representation to the hospital during the early phase following LC was found to be 2.4% in our study. It was observed that 71% of returning patients had presented to the hospital with complaints of abdominal pain. We believe that the rate of 2.4% early return to the hospital in our series is a bit high when all the complications are taken into consideration. This retrospective analysis, however, has shown that this rate can further be decreased by...
Operations Research
Dogan and Yildiz introduce and analyze the pro-con model that is inspired by Franklin’s prudentia... more Dogan and Yildiz introduce and analyze the pro-con model that is inspired by Franklin’s prudential algebra. Consider an agent who is endowed with two sets of orderings: pro- and con-orderings. For each choice set, if an alternative is the top-ranked by a pro-ordering (con-ordering), then this is a pro (con) for choosing that alternative. The alternative with more pros than cons is chosen from each choice set. Each ordering may have a weight reflecting its salience. In this case, the probability that an alternative is chosen equals the difference between the total weights of its pros and cons. Although, this is an additive model similar to the random utility model with structurally invariant primitives, authors show that every (random) choice function is (random) pro-con rational. Their technique requires a generalization of Ford-Fulkerson theorem. The connection between the random model and its deterministic counterpart demonstrates a fruitful use of classical integer programming te...
METU Studies in Development, 2020
In a standard tug-of-war model, two players engage in a component battle each period and a player... more In a standard tug-of-war model, two players engage in a component battle each period and a player wins the contest if her number of battle victories exceeds the other contestant’s by a certain number. In this paper, we introduce a multi-player model of intra-group tug-of-war played by two groups of two players, where a player wins the contest if she wins a certain number of battles more than the other player from her group before either player from the other group achieves the same against one another. We characterize the unique subgame perfect Nash equilibrium of the model and further analyze an asymmetric case with different number of players in the competing groups. Our results indicate an extreme discouragement effect for the laggards and a strong momentum effect for the winner of the first battle.
SSRN Electronic Journal, 2020
We present a new choice model. An agent is endowed with two sets of preferences: pro-preferences ... more We present a new choice model. An agent is endowed with two sets of preferences: pro-preferences and con-preferences. For each choice set, if an alternative is the best (worst) for a pro-preference (con-preference), then this is a pro (con) for choosing that alternative. The alternative with more pros than cons is chosen from each choice set. Each preference may have a weight reflecting its salience. In this case, the probability that an alternative is chosen equals the difference between the weights of its pros and cons. We show that this model provides a unified lens through which every nuance of the rich human choice behavior can be structurally explained. ∗We are grateful to Ariel Rubinstein, Efe Ok, Yusufcan Masatlioglu, Erkut Ozbay, Ed Green, Kfir Eliaz, Mustafa Celebi Pinar, Ran Spiegler, Burak Pac, Paola Manzini, Marco Mariotti, Michael Richter, Battal Dogan, Selman Erol, Faruk Gul, Wolfgang Pesendorfer, Leeat Yariv, David Dillenberger, Pietro Ortoleva, and seminar participa...
In this short paper we propose a preference based extension of the Luce rule, and show that it is... more In this short paper we propose a preference based extension of the Luce rule, and show that it is the only random choice rule that satisfies rejection likelihood additivity. Luce rule asserts that each alternative has a fixed positive weight and from each choice set the probability that an alternative is chosen equals to its relative weight in the given choice set. 1 Since the weight that is assigned to each alternative is positive and there is no ranking of these alternatives, each alternative is chosen from each choice set with positive probability.2 On the other hand, for a decision maker or a group of decision makers, an alternative may clearly dominate the other, therefore from some choice sets some alternatives may not be chosen at all. Motivated with ∗We are grateful to Ariel Rubinstein, Faruk Gul, Efe Ok, and Battal Dogan, seminar participants at Tel Aviv University, NYU, and Bilkent University for their helpful comments. †Bilkent University, Department of Economics. ‡Bilken...
SSRN Electronic Journal, 2020
Journal of Turgut Ozal Medical Center, 2017
Mathematical Social Sciences, 2021
We study bribing in a sequential team contest with multiple pairwise battles. We allow for asymme... more We study bribing in a sequential team contest with multiple pairwise battles. We allow for asymmetries in winning prizes and marginal costs of effort; and we characterize the conditions under which (i) a player in a team is offered a bribe by the owner of the other team and (ii) she accepts the bribe. We show that these conditions depend on the ratios of players' winning prizes and marginal costs of effort: the team owner chooses to bribe the player with the most favorable winning prize to marginal cost of effort ratio, and offer a bribe that leaves her indifferent between accepting (and exerting zero effort) and not accepting (and exerting her optimal effort). In some cases, the competition between players and the negative consequences of one player receiving a bribe on the team performance can drag down equilibrium bribe to zero. We also study the impact of changes in winning prizes and marginal costs of effort on equilibrium bribing behavior.
Journal of Economics & Management Strategy, 2020
We consider a network of heterogeneous agents where each edge represents a two-player contest bet... more We consider a network of heterogeneous agents where each edge represents a two-player contest between the respective nodes. In these bilateral contests, agents compete over an endogenous prize jointly produced using their own contest efforts. We provide a necessary and sufficient condition for the existence of Nash equilibrium and characterize the equilibrium total effort for every agent. Our model has insightful results regarding the network type, that is, depending on whether the network is bipartite or nonbipartite. Finally, considering the sum of all expected utilities as an efficiency notion, we investigate the optimal network structure.
SSRN Electronic Journal, 2017
A new choice model is presented. An agent is endowed with two sets preferences: pro-preferences a... more A new choice model is presented. An agent is endowed with two sets preferences: pro-preferences and con-preferences. For each choice set, if an alternative is the best (worst) for a pro-preference (con-preference), then this is a pro (con) for choosing that alternative. The alternative that has more pros than cons is chosen from each choice set. Each preference may have a weight reflecting its salience. In this case, each alternative is chosen with a probability proportional to the difference between the weights of its pros and cons. We show that this model accommodates every choice behavior. JEL Classification Numbers: D01
Selcuk Tip Dergisi, 2019
Kırk bir yaşında kadın ve 64 yaşında bir erkek hasta karın ağrısı nedeniyle kliniğimize başvurdu.... more Kırk bir yaşında kadın ve 64 yaşında bir erkek hasta karın ağrısı nedeniyle kliniğimize başvurdu. Yapılan tetkiklerinde her iki vakada da karaciğerde dev hemanjiom olduğu raporlandı. Her iki vakada semptomatik olması ve malignite şüphesi olması nedeniyle operasyon kararı alındı. Operasyon esnasında kitlenin karaciğer kaynaklı olmadığı, sağ sürrenal kaynaklı dev adenom olduğu görüldü, ikinci vakada da kitlenin sağ böbrek kaynaklı olduğu görüldü. Rezeksiyon yapıldı. Sürrenal bölgedeki kitlelerin hemanjiomlarla karıştırılabileceği unutulmamalıdır.
SSRN Electronic Journal, 2018
We present a characterization of the Luce rule in terms of positivity and a new choice axiom call... more We present a characterization of the Luce rule in terms of positivity and a new choice axiom called odds supermodularity that strengthens the regularity axiom. This new characterization illuminates a connection that goes unnoticed, and sheds light on the behavioral underpinnings of the Luce rule and its extensions from a different perspective. We also show that odds supermodularity per se characterizes a structured extension of the Luce rule that accommodates zero probability choices.
Public Choice, 2019
In the contest literature, sabotage is defined as a deliberate and costly activity that damages t... more In the contest literature, sabotage is defined as a deliberate and costly activity that damages the opponent's likelihood of winning the contest. Most of the existing results suggest that, anticipating a possible sabotage, contestants would be discouraged from exerting high efforts. In this paper we investigate the act of sabotage in a team contest wherein team members exert costly efforts as a contribution to their team's aggregate effort, which in turn determines the contest's outcome. For the baseline model with no sabotage, there exists a corner equilibrium implying a free-rider problem in each team. As for the model with sabotage, our characterization of Nash equilibrium reveals two important results: (i) a unique interior equilibrium exists so that the free-rider problem no longer is a concern and (ii) the discouragement effect of sabotage vanishes for some players. On top of those conclusions, we investigate the team owner's problems of prize allocation and team formation with the objective being to maximize his team's winning probability.
Journal of Economic Behavior & Organization, 2018
We present a model of race with multiple players and study players' effort choices and expected p... more We present a model of race with multiple players and study players' effort choices and expected prizes in equilibrium. We show that, in equilibrium, once any two players win one battle each, the remaining players do not exert any effort anymore. This turns the continuation game into a two-player race. This is different than the results in previous two-player models of race, which report that all states of the game are reached with positive probabilities. We also provide a set of comparative static results on the effects of the number of players and the victory threshold.
Annals of Medical Research, 2018
First cadaveric kidney transplant was performed in 1933 in Russia by Voronoy (1,2). Renal failure... more First cadaveric kidney transplant was performed in 1933 in Russia by Voronoy (1,2). Renal failure is treated with renal transplantation. After renal transplantation (tx) rate of urinary complications are 5-12.5%. Double-j ureteral stents was developed by Finney in 1978 (3). After renal transplantation double J catheter-related urinary complications are quite rare. Our aim is, in this study we explain ureteral necrosis, and double J catheter was distortion and anastomotic leakage of urine in renal transplant patient.
SSRN Electronic Journal, 2017
A (capacity-constrained) choice problem consists of a set of alternatives and a capacity. A (capa... more A (capacity-constrained) choice problem consists of a set of alternatives and a capacity. A (capacity-constrained) choice rule, at each choice problem, chooses from the alternatives without exceeding the capacity. A choice rule is lexicographic if there exists a list of priority orderings over potential alternatives such that at each choice problem, the set of chosen alternatives is obtainable by choosing the highest ranked alternative according to the first priority ordering, then choosing the highest ranked alternative among the remaining alternatives according to the second priority ordering, and proceeding similarly until the capacity is full or no alternative is left. Lexicographic choice rules have been useful in designing allocation mechanisms for school choice to achieve diversity. We provide a characterization of lexicographic choice rules. We discuss some implications for the Boston school choice system. We also provide a characterization of deferred acceptance mechanisms that operate based on a lexicographic choice structure.
SSRN Electronic Journal, 2016
We introduce and analyze an efficiency criterion for probabilistic assignment of objects, when on... more We introduce and analyze an efficiency criterion for probabilistic assignment of objects, when only ordinal preference information is available. This efficiency criterion is based on the following domination relation: a probabilistic assignment dominates another assignment if it is ex-ante efficient for a strictly larger set of utility profiles consistent with the ordinal preferences. We provide a simple characterization of this domination relation. We revisit an extensively studied assignment mechanism, the Probabilistic Serial mechanism (Bogomolnaia and Moulin, 2001), which always chooses a "fair" assignment. We show that the Probabilistic Serial assignment may be dominated by another fair assignment. We provide conditions under which the serial assignment is undominated among fair assignments.
SSRN Electronic Journal, 2017
Each acceptant and substitutable choice rule is known to have a maximizer-collecting representati... more Each acceptant and substitutable choice rule is known to have a maximizer-collecting representation: there exists a list of priority orderings such that from each choice set that includes more elements than the capacity, the choice is the union of the priority orderings' maximizers (Aizerman and Malishevski, 1981). We introduce the notion of a prime atom and constructively prove that the number of prime atoms of a choice rule determines its smallest size maximizer-collecting representation. We show that responsive choice rules require the maximal number of priority orderings in their maximizer-collecting representations among all acceptant and substitutable choice rules. We characterize maximizer-collecting choice rules in which the number of priorities equals the capacity. We also show that if the capacity is greater than three and the number of elements exceeds the capacity by at least two, then no acceptant and substitutable choice rule has a maximizer-collecting representation of the size equal to the capacity.
Archives of Medical Science - Civilization Diseases, 2017
Surgical laparoscopy, endoscopy & percutaneous techniques, Jan 3, 2015
Laparoscopic cholecystectomy (LC) now has become the golden standard in the treatment of symptoma... more Laparoscopic cholecystectomy (LC) now has become the golden standard in the treatment of symptomatic gallstone cholecystitis. This retrospective analysis was conducted to clarify the reasons of early return to the hospital after discharge following a procedure like LC that has been frequently performed in daily surgical practice. This study covers 586 patients, who were called to follow-ups and thus evaluated, of 676 patients who had had LCs at Meram Medical School's General Surgery Clinic between January 2010 and May 2011. The rate of representation to the hospital during the early phase following LC was found to be 2.4% in our study. It was observed that 71% of returning patients had presented to the hospital with complaints of abdominal pain. We believe that the rate of 2.4% early return to the hospital in our series is a bit high when all the complications are taken into consideration. This retrospective analysis, however, has shown that this rate can further be decreased by...