Tracing the Territory. A Unitary Foundationalist Account

The paper offers an integrative interpretation of the different lines of thought Wittgenstein was inspecting in On Certainty and what he might have been looking for through them. It suggests that we may have been focusing our attention too strongly in the wrong place and comes to a new conclusion about where the real import of these reflections lies. This leads to an answer to the initially posed question of Foundationalism that revises the way in which there can be said to be a grounding intention in On Certainty

On a q-analog of a Sahi result

We obtain a $q$-analog of a well known Sahi result on the joint spectrum of $S(GL_n \times GL_n)$-invariant differential operators with polynomial coefficients on the vector space of complex $n \times n$-matrices.Comment: 9 pages, some improvements in exposition have been mad

Matrix completion by singular value thresholding: sharp bounds

We consider the matrix completion problem where the aim is to esti-mate a large data matrix for which only a relatively small random subset of its entries is observed. Quite popular approaches to matrix completion problem are iterative thresholding methods. In spite of their empirical success, the theoretical guarantees of such iterative thresholding methods are poorly understood. The goal of this paper is to provide strong theo-retical guarantees, similar to those obtained for nuclear-norm penalization methods and one step thresholding methods, for an iterative thresholding algorithm which is a modification of the softImpute algorithm. An im-portant consequence of our result is the exact minimax optimal rates of convergence for matrix completion problem which were known until know only up to a logarithmic factor