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SUMMARY:The Age of Impatience: Optimal Replication Schemes for Opportunist
 ic Networks
DTSTART:20090904T111500
DTSTAMP:20260506T044726Z
UID:6baeeb280fb82563360331762ca8a74e6976c5a22bbcbd361b4afe9b
CATEGORIES:Conferences - Seminars
DESCRIPTION:Augustin Chaintreau\, Thomson Labs\nMobile P2P content dissemi
 nation may leverage the local dedicated  \ncaches provided by hand-held de
 vices (e.g. smart-phones) and  \nopportunistic contacts between these devi
 ces (e.g. via Bluetooth or  \nWiFi). In such a distributed environment\, e
 ach opportunistic contact  \nrepresents a current opportunity to replicate
  local cache content to  \nfulfill future demand. How and when to replicat
 e depends on the  \nheterogeneous popularity of items\, as well as users's
  impatience (i.e.  \nas time passes without fulfillment\, the demanding pe
 er loses interest  \nwith increasing probability). This poses the new ques
 tion on how to  \nensure timely fullfilment by mobile caches in the presen
 ce of  \nephemeral fashions among users.\n\nIn this talk\, we present resu
 lts indicating that this cache allocation  \nproblem can be well understoo
 d and sometimes solved solely through the  \nuse of locally available info
 rmation. We first prove that for any  \nimpatience model and general nodes
  mobility\, the efficiency of a cache  \nallocation satisfy a submodularit
 y property. In the simple case of  \nhomogeneous mobility among a group of
  nodes\, this reduces to a unique  \noptimal allocation which can be fully
  characterized. Moreover\, a  \nsimple adaptive algorithm called "Query Co
 unting Replication" produces  \nthis optimal allocation with no a priori k
 nowledge of nodes' demand  \nand current allocation state. We present some
  results of an early  \nspecification of this algorithm on tops of various
  mobility traces\,  \nwhich emphasizes the importance of a "mandate routin
 g" feature to be  \nimplemented along with this replication rule. The talk
  will conclude  \nwith future works left open by these early steps\, for m
 ore general  \nmobility cases and efficient recommendation engines.
LOCATION:BC 229 https://plan.epfl.ch/?room==BC%20229
STATUS:CONFIRMED
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