13,199 research outputs found
The Method of Alternating Relaxed Projections for two nonconvex sets
The Method of Alternating Projections (MAP), a classical algorithm for
solving feasibility prob- lems, has recently been intensely studied for
nonconvex sets. However, intrinsically available are only local convergence
results: convergence occurs if the starting point is not too far away from
solutions to avoid getting trapped in certain regions. Instead of taking full
projection steps, it can be advantageous to underrelax, i.e., to move only part
way towards the constraint set, in order to enlarge the regions of convergence.
In this paper, we thus systematically study the Method of Alternating Relaxed
Projections (MARP) for two (possibly nonconvex) sets. Complementing our recent
work on MAP, we es- tablish local linear convergence results for the MARP.
Several examples illustrate our analysis
Highly Sensitive Centrality Dependence of Elliptic Flow -- A Novel Signature of the Phase Transition in QCD
Elliptic flow of the hot, dense system which has been created in
nucleus-nucleus collisions develops as a response to the initial azimuthal
asymmetry of the reaction region. Here it is suggested that the magnitude of
this response shows a ``kinky'' dependence on the centrality of collisions for
which the system passes through a first-order or rapid transition between
quark-gluon plasma and hadronic matter. We have studied the system Pb(158AGeV)
on Pb employing a recent version of the transport theoretical approach RQMD and
find the conjecture confirmed. The novel phase transition signature may be
observable in present and forthcoming experiments at CERN-SPS and at RHIC, the
BNL collider.Comment: Version as published in PRL 82 (1999) 2048, title chang
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