BEGIN:VCALENDAR PRODID:-//Microsoft Corporation//Outlook MIMEDIR//EN VERSION:2.0 BEGIN:VEVENT DTSTART:20141118T213000Z DTEND:20141118T220000Z LOCATION:391-92 DESCRIPTION;ENCODING=QUOTED-PRINTABLE:ABSTRACT: Traditional particle simulation methods are used to calculate pairwise potentials, but some problems require 3-body potentials that calculate over triplets of particles. A direct calculation of 3-body interactions involves O(n^3) interactions, but has significant redundant computations that occur in a nested loop formulation. In this paper we explore algorithms for 3-body computations that simultaneously optimize three criteria: computation minimization through symmetries, communication optimality, and load balancing. We present a new 3-body algorithm that is both communication and computation optimal. Its optional replication factor, c, saves c^3 in latency (number of messages) and c^2 in bandwidth (volume), with bounded load-imbalance. We also consider the k-body case and discuss an algorithm that is optimal if there is a cutoff distance of less than 1/3 of the domain. The 3-body algorithm demonstrates 99% efficiency on tens of thousands of cores, showing strong scaling properties with order of magnitude speedups over the naïve algorithm. SUMMARY:A Computation- And Communication-Optimal Parallel Direct 3-Body Algorithm PRIORITY:3 END:VEVENT END:VCALENDAR