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arXiv 0709.4467q-fin.PMcs.NAmath.NAmath.OCmath.PR
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投资组合选择中产生的凸随机优化问题

A Convex Stochastic Optimization Problem Arising from Portfolio Selection

The Chinese University of Hong Kong(香港中文大学)

Hanqing Jin, Zuo Quan Xu, Xun Yu Zhou

AI总结:

研究连续时间投资组合选择中期望效用最大化问题的凸随机优化形式,通过反例揭示拉格朗日乘子不存在、问题不适定及最优解不可达的异常现象,并给出保证唯一最优解存在的显式可验证条件。

摘要:

一个连续时间的金融投资组合选择模型,以期望效用最大化为目标,通常归结为求解一个关于终端财富的(静态)凸随机优化问题,并带有预算约束。文献中通常假设问题适定(即上确界有限)且拉格朗日乘子存在(从而最优解可达)来求解。本文首先通过多个反例表明,这两个假设不一定成立,且最优解不一定存在。这些异常现象反过来对投资组合选择建模和解具有重要的解释和影响。然后研究了拉格朗日乘子不存在、问题不适定和最优解不可达之间的关系。最后,推导出显式且易于验证的条件,这些条件导致找到唯一的最优解。

英文摘要:

A continuous-time financial portfolio selection model with expected utility maximization typically boils down to solving a (static) convex stochastic optimization problem in terms of the terminal wealth, with a budget constraint. In literature the latter is solved by assuming {\it a priori} that the problem is well-posed (i.e., the supremum value is finite) and a Lagrange multiplier exists (and as a consequence the optimal solution is attainable). In this paper it is first shown, via various counter-examples, neither of these two assumptions needs to hold, and an optimal solution does not necessarily exist. These anomalies in turn have important interpretations in and impacts on the portfolio selection modeling and solutions. Relations among the non-existence of the Lagrange multiplier, the ill-posedness of the problem, and the non-attainability of an optimal solution are then investigated. Finally, explicit and easily verifiable conditions are derived which lead to finding the unique optimal solution.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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