Optimal Synchronous Approximate Agreement with Asynchronous Fallback

Approximate Agreement (AA) allows a set of $n$ parties that start with real-valued inputs to obtain values that are at most within a parameter $\epsilon > 0$ from each other and within the range of their inputs. Existing AA protocols, both for the synchronous network model (where any message is delivered within a known delay $\Delta$ time) and the asynchronous network model, are secure when up to $t < n/3$ of the parties are corrupted and require no initial setup (such as a public-key infrastructure (PKI) for signatures). We consider AA protocols where a PKI is available, and show the first AA protocol that achieves simultaneously security against $t_s$ corruptions when the network is synchronous and $t_a$ corruptions when the network is asynchronous, for any $0\le t_a < n/3 \le t_s < n/2$ such that $t_a + 2 \cdot t_s < n$. We further show that our protocol is optimal by proving that achieving AA for $t_a + 2 \cdot t_s \ge n$ is impossible (even with setup). Remarkably, this is also the first AA protocol that tolerates more than $n/3$ corruptions in the synchronous network model

Stochastic Optimization; Proceedings of the International Conference, Kiev, USSR, September 1984

The purpose of this conference, which was attended by 240 scientists from 20 countries, was to survey the latest developments in the field of controlled stochastic processes, stochastic programming, control under incomplete information and applications of stochastic optimization techniques to problems in economics, engineering, modeling of energy systems, etc. The conference reflected a number of recent important developments in the field, notably new results in control theory with incomplete information, stochastic maximum principle, new numerical techniques for stochastic programming and related software, application of probabilistic methods to the modeling of the economy. The contributions to this book are divided into three categories: (1) Controlled stochastic processes; (2) Stochastic extremal problems; and (3) Stochastic optimization problems with incomplete information

Bibliography of Lewis Research Center Technical Publications announced in 1991

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific engineering work performed and managed by the Lewis Research Center in 1991. All the publications were announced in the 1991 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses