Tribes Is Hard in the Message Passing Model

We consider the point-to-point message passing model of communication in which there are $k$ processors with individual private inputs, each $n$-bit long. Each processor is located at the node of an underlying undirected graph and has access to private random coins. An edge of the graph is a private channel of communication between its endpoints. The processors have to compute a given function of all their inputs by communicating along these channels. While this model has been widely used in distributed computing, strong lower bounds on the amount of communication needed to compute simple functions have just begun to appear. In this work, we prove a tight lower bound of $\Omega(kn)$ on the communication needed for computing the Tribes function, when the underlying graph is a star of $k+1$ nodes that has $k$ leaves with inputs and a center with no input. Lower bound on this topology easily implies comparable bounds for others. Our lower bounds are obtained by building upon the recent information theoretic techniques of Braverman et.al (FOCS'13) and combining it with the earlier work of Jayram, Kumar and Sivakumar (STOC'03). This approach yields information complexity bounds that is of independent interest

The Range of Topological Effects on Communication

We continue the study of communication cost of computing functions when inputs are distributed among $k$ processors, each of which is located at one vertex of a network/graph called a terminal. Every other node of the network also has a processor, with no input. The communication is point-to-point and the cost is the total number of bits exchanged by the protocol, in the worst case, on all edges. Chattopadhyay, Radhakrishnan and Rudra (FOCS'14) recently initiated a study of the effect of topology of the network on the total communication cost using tools from $L_1$ embeddings. Their techniques provided tight bounds for simple functions like Element-Distinctness (ED), which depend on the 1-median of the graph. This work addresses two other kinds of natural functions. We show that for a large class of natural functions like Set-Disjointness the communication cost is essentially $n$ times the cost of the optimal Steiner tree connecting the terminals. Further, we show for natural composed functions like $\text{ED} \circ \text{XOR}$ and $\text{XOR} \circ \text{ED}$, the naive protocols suggested by their definition is optimal for general networks. Interestingly, the bounds for these functions depend on more involved topological parameters that are a combination of Steiner tree and 1-median costs. To obtain our results, we use some new tools in addition to ones used in Chattopadhyay et. al. These include (i) viewing the communication constraints via a linear program; (ii) using tools from the theory of tree embeddings to prove topology sensitive direct sum results that handle the case of composed functions and (iii) representing the communication constraints of certain problems as a family of collection of multiway cuts, where each multiway cut simulates the hardness of computing the function on the star topology

Spartan Daily, November 4, 1998

Volume 111, Issue 47https://scholarworks.sjsu.edu/spartandaily/9335/thumbnail.jp

Information behaviour in pre-literate societies.

This chapter arose from an exchange of ideas between a former life scientist, a former archaeologist, and a member of the Kope tribe, a remote tribe in Papua New Guinea. All three now work in fields related to information sciences. It discusses how notions of information have been dominated by text-based information sources, and considers how one group of people (the Kope) managed information in the absence of any awareness of text. The study explores how the Kopi relate to information, how they use it, and where they get it from. It summarises the findings as six information roles. These are related to contemporary situations

Oregon: Round 1 - State-Level Field Network Study of the Implementation of the Affordable Care Act

This report is part of a series of 21 state and regional studies examining the rollout of the ACA. The national network ---- with 36 states and 61 researchers ---- is led by the Rockefeller Institute of Government, the public policy research arm of the State University of New York, the Brookings Institution, and the Fels Institute of Government at the University of Pennsylvania.Oregon has taken an overwhelmingly affirmative response to the ACA, as evidenced by its enthusiastic development and implementation of Cover Oregon and its decision to expand Medicaid. In fact, it is one of six states to receive a Model Testing award from the Centers for Medicare & Medicaid Services, which will support continuing efforts to transform its health care delivery system through innovative methods

Investing in Native Youth: Grantmaking Trends from the Native Youth and Culture Fund

In this report, First Nations highlights a snapshot of grant requests under our Native Youth and Culture Fund from 2010 through 2014