**Weighted Random Survival Forest**

A weighted random survival forest is presented in the paper. It can be regarded as a modification of the random forest improving its performance. The main idea underlying the proposed model is to replace the standard procedure of averaging used for estimation of the random survival forest hazard function by weighted avaraging where the weights are assigned to every tree and can be veiwed as training paremeters which are computed in an optimal way by solving a standard quadratic optimization problem maximizing Harrell’s C-index. Numerical examples with real data illustrate the outperformance of the proposed model in comparison with the original random survival forest. … **OverSketched Newton**

Motivated by recent developments in serverless systems for large-scale machine learning as well as improvements in scalable randomized matrix algorithms, we develop OverSketched Newton, a randomized Hessian-based optimization algorithm to solve large-scale smooth and strongly-convex problems in serverless systems. OverSketched Newton leverages matrix sketching ideas from Randomized Numerical Linear Algebra to compute the Hessian approximately. These sketching methods lead to inbuilt resiliency against stragglers that are a characteristic of serverless architectures. We establish that OverSketched Newton has a linear-quadratic convergence rate, and we empirically validate our results by solving large-scale supervised learning problems on real-world datasets. Experiments demonstrate a reduction of ~50% in total running time on AWS Lambda, compared to state-of-the-art distributed optimization schemes. … **Prima Facie**

Prima facie is a Latin expression meaning on its first encounter or at first sight. The literal translation would be ‘at first face’ or ‘at first appearance’, from the feminine forms of primus (‘first’) and facies (‘face’), both in the ablative case. In modern, colloquial and conversational English, a common translation would be ‘on the face of it’. The term prima facie is used in modern legal English (including both civil law and criminal law) to signify that upon initial examination, sufficient corroborating evidence appears to exist to support a case. In common law jurisdictions, prima facie denotes evidence that, unless rebutted, would be sufficient to prove a particular proposition or fact. The term is used similarly in academic philosophy. Most legal proceedings, in most jurisdictions, require a prima facie case to exist, following which proceedings may then commence to test it, and create a ruling. …

# If you did not already know

**07**
*Tuesday*
May 2019

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