Characterising the function space for Bayesian kernel models We study a non parametric (bayesian) function estimation problem. We observe data $\{Y_i\}$ at points $\{X_i\} \in \mathbb{R}$, perhaps with some noise. We assume that $Y_i = f(X_i)$, for some unknown function $f$. However we want to restrict our choice of functions to be the elements of Reproducing kernel Hilbert space (RKHS) spanned by a fixed kernel K. We model the function through an integral operator, and show that putting prior over the RKHS is equivalent to putting priors over the space of measures on $\mathbb{R}$. Once we have this motivation, we implement using Levy processes. Our method for implementation essentially follows that of Wolpert,R et. al.(See the background paper). No background in RKHS, Levy process will be assumed. After a brief introduction and motivation, we will devote more time on the above topics, and we will look at detail on the reversible jump MCMC involved in the implementation. This is joint work with Qiang,Feng,Sayan,Robert