Most important economic decision problems are sequential, and thus naturally represented as Markov Decision Problems (MDP). After reviewing the theory of MDPs, the applicability of MDPs to real-life sequential decisions appears impractical. The central question addressed in this essay is how...

This paper addresses the joint calibration problem of SPX options and VIX options or futures. We show that the problem can be formulated as a semimartingale optimal transport problem under a finite number of discrete constraints, in the spirit of [arXiv:1906.06478]. We introduce a PDE...

In an environment with stocks and short-term debt, random changes in the risk-reward frontier produce hedging demands for equities, implying that portfolio policies supporting optimal life-cycle consumption are rarely mean-variance efficient. Pursuing optimal life-cycle portfolio policies is...

We give a functional description of the space of stochastic integrals with respect to a given family of martingales, based on the notion of direct integral of Hilbert spaces. We define the multiplicity function of a filtration and show, using our Hilbert space construction, that the multiplicity...

We use minority game model to investigate evolutionary dynamics in complex networks of adaptive agents competing for limited resources. We show that the dynamics and the associated phase structures critically depend on the underlying network organizations, and evolution is a key mechanism for...

We develop a concept of a quot;domineering claimquot; and apply it to the existence, uniqueness and properties of optimal stopping times in continuous time. The notion pinpoints a key observation of pathwise optimality in Davis and Karatzas [8]. It also ties in well with several formulations of...

We propose a new modeling framework to study the asset pricing implications of learning under ambiguity aversion. In a continuous time partial information Lucas economy, we characterize analytically equilibrium equity returns and make the following observations. First, learning under ambiguity...

We solve analytically the Merton's problem of an investor with timeadditive power utility. For general state dynamics, we prove existence of two power series representations of the relevant optimal policies and value functions, which hold for all admissible risk aversion parameters. We...