NONLINEAR EXPECTATIONS AND NONLINEAR MARKOV CHAINS

§1.IntroductionLet(?,F)be a measurable space and let Lb(F)be the space of F-measurable andbounded real functions.A nonlinear expectation is a continuous functionalE[·]:Lb(F)?→Rthat is order preserving(i.e.,E[X1]≥E[X2],if X1≥X2)and constant preserving     

Inversed martingales in risk theory

The theory of inversed martingales is used in order to prove a generalization of a result of H. Cramér on the probability of non-ruin for a classical surplus process if the initial reserve is positive.     

Nonlinear Doob—Meyer Decomposition with Jumps

Concepts of g-supersolution ,g-martingale,g-supermartingale are introduced,wihch are related to BSDE with Brownian motion and Poisson Point process.A strict comparison theorem,monotonic limit theorem related to this type of BSDE are also discussed.As an application of these results,a nonlinear Doob-Meyer decomposition theorem is obtained.     

Doob-meyer decomposition for set-indexed submartingales

Set-indexed martingales and submartingales are defined and studied. The admissible function of a submartingale is defined and some class (D) conditions are given which allow the extension of the function to a -additive measure on the predictable -algebra. Then, we prove a Doob-Meyer decomposition: A set-indexed submartingale can be decomposed into the sum of a weak martingale and an increasing process. A hypothesis of predictability ensures the uniqueness of this decomposition. An explicit construction of the increasing process associated with a submartingale is given. Finally, some remarks, about quasimartingales are discussed.Research supported by a grant from the Natural Sciences and Engineering Research Council of Canada. Dept. of Math. University of Ottawa, Ottawa, Ontario, Canada, K1N 6N5.The third author wishes to thank Professor Ivanoff and Dr. Dozzi for their kind hospitality. Dept. of Math. & Comp. Sci. Bar-Ilan University, Ramat-Gan 52900, Israel.     

集值序上鞅的若干有关问题

本文研究了连续时间的集值序上鞅,在一定的假设下我们证明了集值序上鞅有ｈ－Ｒｉｅｓｚ分解,然后证明了集值序上鞅的Ｄｏｏｂ－Ｍｅｙｅｒ分解定理。     

有摩擦金融市场中的美式未定权益定价

本文研究了高借款利率下投资策略受限制的美式未定权益的定价问题. 文章通过引入反映上述金融市场摩擦的辅助的无摩擦金融市场类给出了美式未定权益的上下套期保值价格$h_{\text{up}}(K)$和$h_{\text{low}}(K)$的定价公式. 进一步, 在基于金融市场无套利的准则下证明了$[h_{\text{low}}(K),h_{\text{up}}(K)]$是美式未定权益的无套利价格区间. 最后在投资策略受到某些具体限制的情形下, 以美式看涨期权为例, 给出了上下套期保值价格的显式表达式或估计式.     

非Lipschitz条件下g 上鞅的非线性Doob Meyer分解

作者讨论非Lipschitz条件下g 上鞅的非线性Doob Meyer 分解.　为此讨论一类漂移系数g(s,·,·)关于(y,z)不满足Lipschitz条 件的倒向随机微分方程解的存在唯一性,运用Biharis不等式证明了一类倒向随机微分方程的比较定理以及g 上解的极限定理.     

数值序上鞅的若干有关问题

本文研究了连续时间的集值序上鞅．在一定的假设下我们证明了集值序上鞅有ｈ－Ｒｉｅｓｚ分解,然后证明了集值序上鞅的Ｄｏｏｂ－Ｍｅｙｅｒ分解定理．     

一般时间区间L~p-半鞅序列的单调极限定理

基于倒向随机微分方程(BSDE)和非线性期望理论中惩罚方法的启发,研究并得到了一般时间区间上L~p-半狹序列的单调极限定理.该结果的证明并非经典结果的平凡推广,新的框架让我们面对许多新问题,它将在一般框架下g-上鞅的Doob-Meyer型分解以及受限BSDE解的存在性等问题的探索中发挥重要作用.