Duality Theory

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Andrzej Ruszczynski - One of the best experts on this subject based on the ideXlab platform.

Erhan Bayraktar - One of the best experts on this subject based on the ideXlab platform.

  • optimal investment with random endowments and transaction costs Duality Theory and shadow prices
    Mathematics and Financial Economics, 2019
    Co-Authors: Erhan Bayraktar
    Abstract:

    This paper studies the utility maximization problem on the terminal wealth with both random endowments and proportional transaction costs. To deal with unbounded random payoffs from some illiquid claims, we propose to work with the acceptable portfolios defined via the consistent price system (CPS) such that the liquidation value processes stay above some stochastic thresholds. In the market consisting of one riskless bond and one risky asset, we obtain a type of the super-hedging result. Based on this characterization of the primal space, the existence and uniqueness of the optimal solution for the utility maximization problem are established using the convex Duality analysis. As an important application of the Duality Theory, we provide some sufficient conditions for the existence of a shadow price process with random endowments in a generalized form as well as in the usual sense using acceptable portfolios.

  • optimal investment with random endowments and transaction costs Duality Theory and shadow prices
    arXiv: Mathematical Finance, 2015
    Co-Authors: Erhan Bayraktar
    Abstract:

    This paper studies the utility maximization on the terminal wealth with random endowments and proportional transaction costs. To deal with unbounded random payoffs from some illiquid claims, we propose to work with the acceptable portfolios defined via the consistent price system (CPS) such that the liquidation value processes stay above some stochastic thresholds. In the market consisting of one riskless bond and one risky asset, we obtain a type of super-hedging result. Based on this characterization of the primal space, the existence and uniqueness of the optimal solution for the utility maximization problem are established using the Duality approach. As an important application of the Duality theorem, we provide some sufficient conditions for the existence of a shadow price process with random endowments in a generalized form as well as in the usual sense using acceptable portfolios.

Walter Schachermayer - One of the best experts on this subject based on the ideXlab platform.

  • Duality Theory for portfolio optimisation under transaction costs
    Annals of Applied Probability, 2016
    Co-Authors: Christoph Czichowsky, Walter Schachermayer
    Abstract:

    We consider the problem of portfolio optimisation with general c adl ag price processes in the presence of proportional transaction costs. In this context, we develop a general Duality Theory. In particular, we prove the existence of a dual optimiser as well as a shadow price process in an appropriate generalised sense. This shadow price is dened by means of a \sandwiched" process consisting of a predictable and an optional strong supermartingale, and pertains to all strategies that remain solvent under transaction costs. We provide examples showing that, in the general setting we study, the shadow price processes have to be of such a generalised form. MSC 2010 Subject Classication: 91G10, 93E20, 60G48

  • Duality Theory for portfolio optimisation under transaction costs
    LSE Research Online Documents on Economics, 2014
    Co-Authors: Christoph Czichowsky, Walter Schachermayer
    Abstract:

    We consider the problem of portfolio optimisation with general cadlag price processes in the presence of proportional transaction costs. In this context, we develop a general Duality Theory. In particular, we prove the existence of a dual optimiser as well as a shadow price process in an appropriate generalised sense. This shadow price is defined by means of a "sandwiched" process consisting of a predictable and an optional strong supermartingale, and pertains to all strategies that remain solvent under transaction costs. We provide examples showing that, in the general setting we study, the shadow price processes have to be of such a generalised form.

Alberto Ravagnani - One of the best experts on this subject based on the ideXlab platform.

  • rank metric codes and their Duality Theory
    Designs Codes and Cryptography, 2016
    Co-Authors: Alberto Ravagnani
    Abstract:

    We compare the two Duality theories of rank-metric codes proposed by Delsarte and Gabidulin, proving that the former generalizes the latter. We also give an elementary proof of MacWilliams identities for the general case of Delsarte rank-metric codes. The identities which we derive are very easy to handle, and allow us to re-establish in a very concise way the main results of the Theory of rank-metric codes first proved by Delsarte employing association schemes and regular semilattices. We also show that our identities imply as a corollary the original MacWilliams identities established by Delsarte. We describe how the minimum and maximum rank of a rank-metric code relate to the minimum and maximum rank of the dual code, giving some bounds and characterizing the codes attaining them. Then we study optimal anticodes in the rank metric, describing them in terms of optimal codes (namely, MRD codes). In particular, we prove that the dual of an optimal anticode is an optimal anticode. Finally, as an application of our results to a classical problem in enumerative combinatorics, we derive both a recursive and an explicit formula for the number of $$k \times m$$k×m matrices over a finite field with given rank and $$h$$h-trace.

  • rank metric codes and their Duality Theory
    arXiv: Information Theory, 2014
    Co-Authors: Alberto Ravagnani
    Abstract:

    We compare the two Duality theories of rank-metric codes proposed by Delsarte and Gabidulin, proving that the former generalizes the latter. We also give an elementary proof of MacWilliams identities for the general case of Delsarte rank-metric codes. The identities which we derive are very easy to handle, and allow us to re-establish in a very concise way the main results of the Theory of rank-metric codes first proved by Delsarte employing the Theory of association schemes and regular semilattices. We also show that our identities imply as a corollary the original MacWilliams identities established by Delsarte. We describe how the minimum and maximum rank of a rank-metric code relate to the minimum and maximum rank of the dual code, giving some bounds and characterizing the codes attaining them. Then we study optimal anticodes in the rank metric, describing them in terms of optimal codes (namely, MRD codes). In particular, we prove that the dual of an optimal anticode is an optimal anticode. Finally, as an application of our results to a classical problem in enumerative combinatorics, we derive both a recursive and an explicit formula for the number of $k \times m$ matrices over a finite field with given rank and $h$-trace.

Christoph Czichowsky - One of the best experts on this subject based on the ideXlab platform.

  • Duality Theory for portfolio optimisation under transaction costs
    Annals of Applied Probability, 2016
    Co-Authors: Christoph Czichowsky, Walter Schachermayer
    Abstract:

    We consider the problem of portfolio optimisation with general c adl ag price processes in the presence of proportional transaction costs. In this context, we develop a general Duality Theory. In particular, we prove the existence of a dual optimiser as well as a shadow price process in an appropriate generalised sense. This shadow price is dened by means of a \sandwiched" process consisting of a predictable and an optional strong supermartingale, and pertains to all strategies that remain solvent under transaction costs. We provide examples showing that, in the general setting we study, the shadow price processes have to be of such a generalised form. MSC 2010 Subject Classication: 91G10, 93E20, 60G48

  • Duality Theory for portfolio optimisation under transaction costs
    LSE Research Online Documents on Economics, 2014
    Co-Authors: Christoph Czichowsky, Walter Schachermayer
    Abstract:

    We consider the problem of portfolio optimisation with general cadlag price processes in the presence of proportional transaction costs. In this context, we develop a general Duality Theory. In particular, we prove the existence of a dual optimiser as well as a shadow price process in an appropriate generalised sense. This shadow price is defined by means of a "sandwiched" process consisting of a predictable and an optional strong supermartingale, and pertains to all strategies that remain solvent under transaction costs. We provide examples showing that, in the general setting we study, the shadow price processes have to be of such a generalised form.