scholarly journals A non-local free boundary problem arising in a theory of financial bubbles

Author(s):  
Henri Berestycki ◽  
Regis Monneau ◽  
José A. Scheinkman

We consider an evolution non-local free boundary problem that arises in the modelling of speculative bubbles. The solution of the model is the speculative component in the price of an asset. In the framework of viscosity solutions, we show the existence and uniqueness of the solution. We also show that the solution is convex in space, and establish several monotonicity properties of the solution and of the free boundary with respect to parameters of the problem. To study the free boundary, we use, in particular, the fact that the odd part of the solution solves a more standard obstacle problem. We show that the free boundary is and describe the asymptotics of the free boundary as c , the cost of transacting the asset, goes to zero.

2018 ◽  
Vol 45 (1) ◽  
pp. 59-73
Author(s):  
Avetik Arakelyan ◽  
Rafayel Barkhudaryan ◽  
Henrik Shahgholian ◽  
Mohammad Salehi

2007 ◽  
Vol 17 (01) ◽  
pp. 63-80 ◽  
Author(s):  
YOUSHAN TAO ◽  
HUI ZHANG

We consider a procedure for cancer therapy which consists of injecting replication-competent viruses into the tumor. The viruses infect tumor cells, replicate inside them, and eventually cause their death. As infected cells die, the viruses inside them are released and then proceed to infect adjacent tumor cells. However, a major factor influencing the efficacy of virus agents is the immune response that may limit the replication and spread of the replication-competent virus. The competition between tumor cells, a replication-competent virus and an immune response is modelled as a free boundary problem for a nonlinear system of partial differential equations, where the free boundary is the surface of the tumor. In this model, the immune response equation is a semilinear parabolic equation, including a chemotaxis term which is used to describe the movement of the immune response induced by gradients of the infected cell density. Under the assumption that the chemotactic sensitivity coefficient is small compared with the diffusion coefficient of the immune response, we prove the global existence and uniqueness of the solution of this free boundary problem. For large chemotactic coefficient, the global existence is still open.


2015 ◽  
Vol 95 (12) ◽  
pp. 2794-2806 ◽  
Author(s):  
R. Barkhudaryan ◽  
M. Juráš ◽  
M. Salehi

2012 ◽  
Vol 24 (2) ◽  
pp. 231-271 ◽  
Author(s):  
SONG LIPING ◽  
YU WANGHUI

A free boundary problem, which comes from the model of the perpetual American call options with utility functions in financial market, is investigated. It is a degenerative parabolic free boundary problem and is studied by the line method. The existence, regularity and uniqueness of the solution as well as some properties of the free boundary are established.


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