16,147 research outputs found
An asynchronous, forward-backward, distributed generalized Nash equilibrium seeking algorithm
In this paper, we propose an asynchronous distributed algorithm for the
computation of generalized Nash equilibria in noncooperative games, where the
players interact via an undirected communication graph. Specifically, we extend
the paper "Asynchronous distributed algorithm for seeking generalized Nash
equilibria" by Yi and Pavel: we redesign the asynchronous update rule using
auxiliary variables over the nodes rather than over the edges. This key
modification renders the algorithm scalable for highly interconnected games.
The derived asynchronous algorithm is robust against delays in the
communication and it eliminates the idle times between computations, hence
modeling a more realistic interaction between players with different update
frequencies. We address the problem from an operator-theoretic perspective and
design the algorithm via a preconditioned forward-backward splitting. Finally,
we numerically simulate the algorithm for the Cournot competition in networked
markets.Comment: Submitted to European Control Conference 2019 (under review
A Theory of Partitioned Global Address Spaces
Partitioned global address space (PGAS) is a parallel programming model for
the development of applications on clusters. It provides a global address space
partitioned among the cluster nodes, and is supported in programming languages
like C, C++, and Fortran by means of APIs. In this paper we provide a formal
model for the semantics of single instruction, multiple data programs using
PGAS APIs. Our model reflects the main features of popular real-world APIs such
as SHMEM, ARMCI, GASNet, GPI, and GASPI.
A key feature of PGAS is the support for one-sided communication: a node may
directly read and write the memory located at a remote node, without explicit
synchronization with the processes running on the remote side. One-sided
communication increases performance by decoupling process synchronization from
data transfer, but requires the programmer to reason about appropriate
synchronizations between reads and writes. As a second contribution, we propose
and investigate robustness, a criterion for correct synchronization of PGAS
programs. Robustness corresponds to acyclicity of a suitable happens-before
relation defined on PGAS computations. The requirement is finer than the
classical data race freedom and rules out most false error reports.
Our main result is an algorithm for checking robustness of PGAS programs. The
algorithm makes use of two insights. Using combinatorial arguments we first
show that, if a PGAS program is not robust, then there are computations in a
certain normal form that violate happens-before acyclicity. Intuitively,
normal-form computations delay remote accesses in an ordered way. We then
devise an algorithm that checks for cyclic normal-form computations.
Essentially, the algorithm is an emptiness check for a novel automaton model
that accepts normal-form computations in streaming fashion. Altogether, we
prove the robustness problem is PSpace-complete
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