Investigation of Inverse Problems for the Heat equation Based on the Theory of Stochastic Control

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We study the inverse problem determining the shape of some unknown portion of the boundary of a domain based on parabolic equations and also study the one determining the heat conduction coefficients of a heat equation based on the theory of stochastic control. The former is treated through a suitably linearized equation by analytical method. The shape of deforming unknown portion is allowed depending on time and is assumed only to be Lipschitz continuous. The latter provides us with a new type of stochastic control. That is, the running cost is driven by the local time at the measurement place with respect to the controlled diffusion process. Therefore the corresponding HJB equation has singular source term involving the Dirac function supported on the measurement place.In the framework of stochastic control, we also consider some jump process concerned with common property resource and obtain an optimal control variable under suitable conditions.Related to the subject, we need to study some property of systems of orthogonal functions. In particular, the classical Hardy's inequality is extended to the case of Jacobi series and the boundedness of the transplantation operators and Cesaro operators are obtained.Finally, from a viewpoint of numerical analysis, we study some random sequences. An ultradiscrete dynamical system is constructed under consideration of discretized Markov transforms and bit error probabilities of certain communication systems are discussed by using spreading sequences of Markov chains.