In this talk we discuss a utility-deviation risk portfolio selection problem. By considering the first order condition for the objective function, we derive a primitive static problem, called Nonlinear Moment Problem, subject to a set of constraints involving nonlinear functions of “mean-field terms”, to completely characterize the optimal terminal wealth. Under a mild assumption on utility, we establish the existence of the optimal solutions for both utility-downside-risk and utility-strictly-convex-risk problems, their positive answers have long been missing in the literature. In particular, the existence result in utility-downside-risk problem is in contrast with that of mean-downside-risk problem considered in Jin-Yan-Zhou (2005) in which they prove the non-existence of optimal solution instead and we can show the same non-existence result via the corresponding Nonlinear Moment Problem. (Joint work with K.C. Wong and S.C.P. Yam)

In this talk, we consider the optimal dividend payment strategy for an insurance company, having two collaborating business lines. The surpluses of the business lines are modelled by diffusion processes. The collaboration between the two business lines permits that money can be transferred from one line to another with or without transaction costs while money must be transferred from one line to another to help both business lines keep running before simultaneous ruin of the two lines eventually occur. (Joint work with J.W. Gu and M. Steffensen)

A face of an oriented knot diagram on the two sphere is called a coherent (resp. incoherent) region if the orientation of its boundary is coherent (resp. incoherent). In this talk, we investigate the number of the coherent faces and incoherent faces of an oriented knot diagram, and give some relations between the number of the incoherent regions and the canonical genus of a knot. This is a joint work with Kokoro Tanaka (Tokyo Gakugei University)

The canonicai genus of a Whitehead double of a knot is less than or equal to its crossing number. Tripp observed that the equality holds for 2-braid knots and conjectured that the equality holds for all knots. However, Jang and Lee found counterexamples for this conjecture. In this talk, we discuss this conjecture for non-prime alternating knots.