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Papers by Alejandro Cataldo
This paper studies the problem facing a firm of determining the optimal composition and pricing o... more This paper studies the problem facing a firm of determining the optimal composition and pricing of multiple bundles offered in a market where they compete with other bundles. The analysis assumes that the prices and characteristics of the competitor’s bundles are known and that the competition does not react in the short run to the firm’s decisions. Consumers are assumed to be rational and to maximize a random utility function. The problem is modeled as a mixed integer non-linear program, which by its nature is difficult to solve using traditional methods. A novel two-phase solution approach is therefore developed. The first phase derives a closed-form expression to solve the optimal pricing subproblem for the bundles assuming their composition is known, and the second phase then uses this expression to arrive at an optimal solution to the composition subproblem.
Annals of Operations Research, 2016
Revista médica de Chile, 2016
Annals of Operations Research
International Transactions in Operational Research
A novel solution approach is developed for the scheduling of chemotherapy sessions at cancer trea... more A novel solution approach is developed for the scheduling of chemotherapy sessions at cancer treatment centers. The problem is divided into two subproblems determining the day (interday scheduling) and the time slots (intraday scheduling), respectively. The interday subproblem is solved by a model that allows for effective treatment center capacity choices while the intraday subproblem is addressed using two optimization models. New patient arrivals and treatment protocols specifying the latest starting date and session spacing are sources of uncertainty. Unlike other existing approaches, the proposed method incorporates the concept of effective treatment capacity which facilitates the interaction between the interday and intraday subproblems allowing them to be solved sequentially and iteratively to thus achieve much more resource‐efficient solutions. A case study using real data from a Chilean cancer center to conduct comparative simulations of its manual scheduling methods and th...
En este trabajo se formula un modelo de programacion lineal entera apropiado para su resolucion m... more En este trabajo se formula un modelo de programacion lineal entera apropiado para su resolucion mediante un enfoque de generacion para un problema de ruteo con inventarios. El problema estudiado se basa en el problema de administracion de fondos disponibles en los distintos cajeros de una red de cajeros automaticos y el ruteo de los camiones que realizan la reposicion y retiro en los cajeros de la red. A diferencia de la mayoŕia de los problemas de ruteo con inventario estudiados previamente en la literatura [1] nuestro caso considera la posibilidad de faltante de dinero para satisfacer extracciones de los clientes (out-of-stocks) los que tienen un costo para el sistema. Para construir el problema maestro se incluyen variables “estaticas” relativas a los niveles de stock de dinero en los cajeros y a los out-of-stocks mientras que las variables correspondientes a la seleccion de rutas son generadas de manera dinamica. Los subproblemas correspondientes son resueltos con un modelo de c...
Annals of Operations Research, 2018
Health care management science, Jan 17, 2018
Hospital emergency departments are often overcrowded, resulting in long wait times and a public p... more Hospital emergency departments are often overcrowded, resulting in long wait times and a public perception of poor attention. Delays in transferring patients needing further treatment increases emergency department congestion, has negative impacts on their health and may increase their mortality rates. A model built around a Markov decision process is proposed to improve the efficiency of patient flows between the emergency department and other hospital units. With each day divided into time periods, the formulation estimates bed demand for the next period as the basis for determining a proactive rather than reactive transfer decision policy. Due to the high dimensionality of the optimization problem involved, an approximate dynamic programming approach is used to derive an approximation of the optimal decision policy, which indicates that a certain number of beds should be kept free in the different units as a function of the next period demand estimate. Testing the model on two in...
European Journal of Operational Research, 2017
Journal of Industrial & Management Optimization, 2017
International Journal of Production Research, 2016
In this paper, we propose an extension of the problem of bundling with multinomial logit, making ... more In this paper, we propose an extension of the problem of bundling with multinomial logit, making an explicit inclusion of the consumers’ maximum willingness to pay (MWTP) by means of the constrained multinomial logit (CMNL). In the bundling problem, we determine the price and the composition of bundles offered for a single segment of consumers by a firm, which is competing with others in the market, and we compare this result to a base case in which the consumers’ MWTP is not considered. We assume these consumers as rational since they choose the bundle that maximise their utility and the bundle price is within their MWTP. The resulting model is a non-linear mixed integer programme which is solved in two steps: (i) pricing is the first step; the prices are numerically determined in a fixed point equations system and (ii) in the second step the composition of the bundle is determined by explicit enumeration. The results show that the price obtained is less than the one got in the case without CMNL (and bigger than the costs), and the composition of the offered bundle is different as well. It is possible to conclude that not considering the consumers’ MWTP in the context of the problem of bundling will imply an overestimation of the firm’s profit. We have analysed as well the results for a Chilean telecommunications company. These results show the importance of including the MWTP in the pricing and composition process.
This paper studies the problem facing a firm of determining the optimal composition and pricing o... more This paper studies the problem facing a firm of determining the optimal composition and pricing of multiple bundles offered in a market where they compete with other bundles. The analysis assumes that the prices and characteristics of the competitor’s bundles are known and that the competition does not react in the short run to the firm’s decisions. Consumers are assumed to be rational and to maximize a random utility function. The problem is modeled as a mixed integer non-linear program, which by its nature is difficult to solve using traditional methods. A novel two-phase solution approach is therefore developed. The first phase derives a closed-form expression to solve the optimal pricing subproblem for the bundles assuming their composition is known, and the second phase then uses this expression to arrive at an optimal solution to the composition subproblem.
Annals of Operations Research, 2016
Revista médica de Chile, 2016
Annals of Operations Research
International Transactions in Operational Research
A novel solution approach is developed for the scheduling of chemotherapy sessions at cancer trea... more A novel solution approach is developed for the scheduling of chemotherapy sessions at cancer treatment centers. The problem is divided into two subproblems determining the day (interday scheduling) and the time slots (intraday scheduling), respectively. The interday subproblem is solved by a model that allows for effective treatment center capacity choices while the intraday subproblem is addressed using two optimization models. New patient arrivals and treatment protocols specifying the latest starting date and session spacing are sources of uncertainty. Unlike other existing approaches, the proposed method incorporates the concept of effective treatment capacity which facilitates the interaction between the interday and intraday subproblems allowing them to be solved sequentially and iteratively to thus achieve much more resource‐efficient solutions. A case study using real data from a Chilean cancer center to conduct comparative simulations of its manual scheduling methods and th...
En este trabajo se formula un modelo de programacion lineal entera apropiado para su resolucion m... more En este trabajo se formula un modelo de programacion lineal entera apropiado para su resolucion mediante un enfoque de generacion para un problema de ruteo con inventarios. El problema estudiado se basa en el problema de administracion de fondos disponibles en los distintos cajeros de una red de cajeros automaticos y el ruteo de los camiones que realizan la reposicion y retiro en los cajeros de la red. A diferencia de la mayoŕia de los problemas de ruteo con inventario estudiados previamente en la literatura [1] nuestro caso considera la posibilidad de faltante de dinero para satisfacer extracciones de los clientes (out-of-stocks) los que tienen un costo para el sistema. Para construir el problema maestro se incluyen variables “estaticas” relativas a los niveles de stock de dinero en los cajeros y a los out-of-stocks mientras que las variables correspondientes a la seleccion de rutas son generadas de manera dinamica. Los subproblemas correspondientes son resueltos con un modelo de c...
Annals of Operations Research, 2018
Health care management science, Jan 17, 2018
Hospital emergency departments are often overcrowded, resulting in long wait times and a public p... more Hospital emergency departments are often overcrowded, resulting in long wait times and a public perception of poor attention. Delays in transferring patients needing further treatment increases emergency department congestion, has negative impacts on their health and may increase their mortality rates. A model built around a Markov decision process is proposed to improve the efficiency of patient flows between the emergency department and other hospital units. With each day divided into time periods, the formulation estimates bed demand for the next period as the basis for determining a proactive rather than reactive transfer decision policy. Due to the high dimensionality of the optimization problem involved, an approximate dynamic programming approach is used to derive an approximation of the optimal decision policy, which indicates that a certain number of beds should be kept free in the different units as a function of the next period demand estimate. Testing the model on two in...
European Journal of Operational Research, 2017
Journal of Industrial & Management Optimization, 2017
International Journal of Production Research, 2016
In this paper, we propose an extension of the problem of bundling with multinomial logit, making ... more In this paper, we propose an extension of the problem of bundling with multinomial logit, making an explicit inclusion of the consumers’ maximum willingness to pay (MWTP) by means of the constrained multinomial logit (CMNL). In the bundling problem, we determine the price and the composition of bundles offered for a single segment of consumers by a firm, which is competing with others in the market, and we compare this result to a base case in which the consumers’ MWTP is not considered. We assume these consumers as rational since they choose the bundle that maximise their utility and the bundle price is within their MWTP. The resulting model is a non-linear mixed integer programme which is solved in two steps: (i) pricing is the first step; the prices are numerically determined in a fixed point equations system and (ii) in the second step the composition of the bundle is determined by explicit enumeration. The results show that the price obtained is less than the one got in the case without CMNL (and bigger than the costs), and the composition of the offered bundle is different as well. It is possible to conclude that not considering the consumers’ MWTP in the context of the problem of bundling will imply an overestimation of the firm’s profit. We have analysed as well the results for a Chilean telecommunications company. These results show the importance of including the MWTP in the pricing and composition process.