{"title":"Importance Sampling, Large Deviations, and Differential Games","authors":"P. Dupuis, Hui Wang","doi":"10.1080/10451120410001733845","DOIUrl":"https://doi.org/10.1080/10451120410001733845","url":null,"abstract":"A standard heuristic in the area of importance sampling is that the changes of measure used to prove large deviation lower bounds give good performance when used for importance sampling. Recent work, however, has shown that a naive implementation of the heuristic is incorrect in many situations. The present paper considers the simple setting of sums of independent and identically distributed (iid) random variables, and shows that under mild conditions asymptotically optimal changes of measure can be found if one considers dynamic importance sampling schemes. For such schemes, the change of measure applied to an individual summand can depend on the historical empirical mean of the simulation (i.e. the system state). In analyzing the asymptotic performance of importance sampling, we show that the value function of a differential game characterizes the optimal performance, with player A corresponding to the choice of change of measure and player B arising due to a large deviations analysis. From this perspective, the traditional implementation of the heuristic is shown to correspond to player A choosing a control that is fixed, regardless of the system state or player B's choice of control. This leads to an \"open loop\" control for player A, which is suboptimal except in special cases. Our final contribution is a method, based on the Isaacs equation associated with the differential game, for constructing dynamic schemes. Numerical examples are presented to illustrate the results.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"249 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114543765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hyperfinite Lévy Processes","authors":"T. Lindstrøm","doi":"10.1080/10451120412331315797","DOIUrl":"https://doi.org/10.1080/10451120412331315797","url":null,"abstract":"A hyperfinite Lévy process is an infinitesimal random walk (in the sense of nonstandard analysis) which with probability one is finite for all finite times. We develop the basic theory for hyperfinite Lévy processes and find a characterization in terms of transition probabilities. The standard part of a hyperfinite Lévy process is a (standard) Lévy process, and we show that given a generating triplet (γ, C, μ) for standard Lévy processes, we can construct hyperfinite Lévy processes whose standard parts correspond to this triplet. Hence all Lévy laws can be obtained from hyperfinite Lévy processes. The paper ends with a brief look at Malliavin calculus for hyperfinite Lévy processes including a version of the Clark-Haussmann-Ocone formula.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131079189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Spread of branching diffusion: Sharp asymptotics","authors":"A. Korostelev, O. Korosteleva","doi":"10.1080/10451120412331313447","DOIUrl":"https://doi.org/10.1080/10451120412331313447","url":null,"abstract":"A one-dimensional branching diffusion with a stable drift is considered. Let Rt denote the position of the rightmost particle at time t. It is shown that Rt , properly normalized, has a limiting distribution.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125457825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Further calculations for Israeli options","authors":"E. Baurdoux, A. Kyprianou","doi":"10.1080/10451120412331313438","DOIUrl":"https://doi.org/10.1080/10451120412331313438","url":null,"abstract":"Recently Kifer introduced the concept of an Israeli (or Game) option. That is a general American-type option with the added possibility that the writer may terminate the contract early inducing a payment not less than the holder's claim had they exercised at that moment. Kifer shows that pricing and hedging of these options reduces to evaluating a stochastic saddle point problem associated with Dynkin games. Kyprianou, A.E. (2004) \"Some calculations for Israeli options\", Fin. Stoch. 8, 73-86 gives two examples of perpetual Israeli options where the value function and optimal strategies may be calculated explicity. In this article, we give a third example of a perpetual Israeli option where the contingent claim is based on the integral of the price process. This time the value function is shown to be the unique solution to a (two sided) free boundary value problem on (0, ∞) which is solved by taking an appropriately rescaled linear combination of Kummer functions. The probabilistic methods we appeal to in this paper centre around the interaction between the analytic boundary conditions in the free boundary problem, Itô's formula with local time and the martingale, supermartingle and submartingale properties associated with the solution to the stochastic saddle point problem.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129033802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Lévy Approximation of Increment Processes with Markov Switching","authors":"V. Korolyuk, N. Limnios","doi":"10.1080/10451120412331292207","DOIUrl":"https://doi.org/10.1080/10451120412331292207","url":null,"abstract":"We study weak convergence of increment processes with embedded Markov chain switching in a series scheme. The limit process is a Lévy process where the jump part is a compound Poisson process. A result concerning the rate of convergence is also given. This study is motivated by risk theory and its applications.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"569 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129491333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Corrigendum: Large deviations for multi-dimensional reflected fractional Brownian motion","authors":"K. Majewski","doi":"10.1080/10451120412331295963","DOIUrl":"https://doi.org/10.1080/10451120412331295963","url":null,"abstract":"(Received 27 July 2004) Stochastics and Stochastics Reports, 75(4) (2003), 233-257. In the proof of theorem 3, I gave an obviously wrong reason for the step where the large deviation principle for fractional Brownian motion is strengthened from the topology of point-wise convergence to the topology of uniform convergence on compacts. With lemma 6 of Ref. [2] and the main result of Ref. [3] this error can be corrected. Alternative proofs for theorem 3 can be found in Refs. [1,4]. Two detected typos:","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121703409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Measure-valued Markov processes and stochastic flows on abstract spaces","authors":"A. Dorogovtsev","doi":"10.1080/10451120422331292216","DOIUrl":"https://doi.org/10.1080/10451120422331292216","url":null,"abstract":"We consider measure-valued processes with constant mass in Hilbert space. The stochastic flow which carries the mass satisfies a stochastic differential equation with coefficients depending on the mass distribution. This mass distribution can be considered as the conditional distribution of the solution of a certain SDE. In contrast to the filtration equation, in our case the random measure cannot diffuse: a single particle cannot break up or turn into clouds. The Markov structure of the measure-valued processes obtained is studied and a comparison with Fleming–Viot processes is presented.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123731715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Existence and uniqueness for solutions of one dimensional SDE's driven by an additive fractional noise","authors":"L. Denis, M. Erraoui, Y. Ouknine","doi":"10.1080/10451120412331299336","DOIUrl":"https://doi.org/10.1080/10451120412331299336","url":null,"abstract":"Let be a fractional Brownian motion with Hurst parameter H. We study the stochastic differential equation where b is continuous in x and with We show that the set of pathwise solutions (not necessarily adapted) is a funnel whose upper and lower bounds are strong solutions (hence adapted). In both cases, and we give a uniqueness criterion which relaxes usual conditions. Moreover, in case we obtain a criterion of existence and uniqueness without any continuity assumption on b.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134049031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Probabilistic interpretation of a system of quasilinear parabolic PDEs","authors":"A.B. Sow *, É. Pardoux","doi":"10.1080/10451120412331303150","DOIUrl":"https://doi.org/10.1080/10451120412331303150","url":null,"abstract":"Using a forward–backward stochastic differential equations (FBSDE) associated to a transmutation process driven by a finite sequence of Poisson processes, we obtain a probabilistic interpretation for a non-degenerate system of quasilinear parabolic partial differential equations (PDEs). The novetly is that the linear second order differential operator is different on each line of the system.","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132031317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On approximation of a class of stochastic integrals and interpolation","authors":"C. Geiss, Stefan Geiss †","doi":"10.1080/10451120410001728445","DOIUrl":"https://doi.org/10.1080/10451120410001728445","url":null,"abstract":"Given a diffusion we give different equivalent conditions so that a stochastic integral has an L 2-approximation rate of n −η, if one approximates by integrals over piece-wise constant integrands where equidistant time nets of cardinality are used. In particular, we obtain assertions in terms of smoothness properties of g(Y T ) in the sense of Malliavin calculus. After optimizing over non-equidistant time-nets of cardinality in case , it turns out that one always obtains a rate of which is optimal. This applies to all functions g obtained in an appropriate way by the real interpolation method between the weighted Sobolev space D 1,2(μ) and L 2(μ), where μ is related to the law of Y T . Finally, we obtain the result that if and only if the equidistant time nets attain the optimal rate of convergence","PeriodicalId":289792,"journal":{"name":"Stochastics and Stochastic Reports","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122179531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}