Online Metric Tracking and Smoothing

We consider the online smoothing problem , in which a tracker is required to maintain distance no more than Δ≥0 from a time-varying signal f while minimizing its own movement. The problem is determined by a metric space ( X , d ) with an associated cost function c :ℝ→ℝ. Given a signal f 1 , f 2 ,…∈...

Celý popis

Uložené v:

Podrobná bibliografia
Vydané v:	Algorithmica Ročník 68; číslo 1; s. 133 - 151
Hlavní autori:	Chen, Sixia, Russell, Alexander
Médium:	Journal Article
Jazyk:	English
Vydavateľské údaje:	Boston Springer US 01.01.2014 Springer
Predmet:	Algorithm Analysis and Problem Complexity Algorithmics. Computability. Computer arithmetics Algorithms Applied sciences Computer Science Computer science; control theory; systems Computer Systems Organization and Communication Networks Data Structures and Information Theory Exact sciences and technology Mathematics of Computing Theoretical computing Theory of Computation Online algorithms Randomized algorithms On line Tracking Proximity Metric space Fixed cost Competitiveness Algorithmics Online algorithm Randomized algorithm Time varying system Smoothing Metric Deterministic algorithms
ISSN:	0178-4617, 1432-0541
On-line prístup:	Získať plný text
Tagy:	Pridať tag Žiadne tagy, Buďte prvý, kto otaguje tento záznam!

Abstract	We consider the online smoothing problem , in which a tracker is required to maintain distance no more than Δ≥0 from a time-varying signal f while minimizing its own movement. The problem is determined by a metric space ( X , d ) with an associated cost function c :ℝ→ℝ. Given a signal f 1 , f 2 ,…∈ X the tracker is responsible for producing a sequence a 1 , a 2 ,… of elements of X that meet the proximity constraint: d ( f i , a i )≤Δ. To complicate matters, the tracker is on-line—the value a i may only depend on f 1 ,…, f i —and wishes to minimize the cost of his travels, ∑ c ( d ( a i , a i +1 )). We evaluate such tracking algorithms competitively, comparing this with the cost achieved by an optimal adversary apprised of the entire signal in advance. The problem was originally proposed by Yi and Zhang (In: Proceedings of the 20th annual ACM-SIAM symposium on discrete algorithms (SODA), pp. 1098–1107. ACM Press, New York, 2009 ), who considered the natural circumstance where the metric spaces are taken to be ℤ k with the ℓ 2 metric and the cost function is equal to 1 unless the distance is zero (thus the tracker pays a fixed cost for any nonzero motion). We begin by studying arbitrary metric spaces with the “pay if you move” metric of Yi and Zhang (In: Proceedings of the 20th annual ACM-SIAM symposium on discrete algorithms (SODA), pp. 1098–1107. ACM Press, New York, [ 2009 ]) described above and describe a natural randomized algorithm that achieves a O (log b Δ )-competitive ratio, where b Δ =max x ∈ X \| B Δ ( x )\| is the maximum number of points appearing in any ball of radius Δ. We show that this bound is tight. We then focus on the metric space ℤ with natural families of monotone cost functions c ( x )= x p for some p ≥0. We consider both the expansive case ( p ≥1) and the contractive case ( p <1), and show that the natural lazy algorithm performs well in the expansive case. In the contractive case, we introduce and analyze a novel deterministic algorithm that achieves a constant competitive ratio depending only on p . Finally, we observe that by slightly relaxing the guarantee provided by the tracker, one can obtain natural analogues of these algorithms that work in continuous metric spaces.
AbstractList	We consider the online smoothing problem , in which a tracker is required to maintain distance no more than Δ≥0 from a time-varying signal f while minimizing its own movement. The problem is determined by a metric space ( X , d ) with an associated cost function c :ℝ→ℝ. Given a signal f 1 , f 2 ,…∈ X the tracker is responsible for producing a sequence a 1 , a 2 ,… of elements of X that meet the proximity constraint: d ( f i , a i )≤Δ. To complicate matters, the tracker is on-line—the value a i may only depend on f 1 ,…, f i —and wishes to minimize the cost of his travels, ∑ c ( d ( a i , a i +1 )). We evaluate such tracking algorithms competitively, comparing this with the cost achieved by an optimal adversary apprised of the entire signal in advance. The problem was originally proposed by Yi and Zhang (In: Proceedings of the 20th annual ACM-SIAM symposium on discrete algorithms (SODA), pp. 1098–1107. ACM Press, New York, 2009 ), who considered the natural circumstance where the metric spaces are taken to be ℤ k with the ℓ 2 metric and the cost function is equal to 1 unless the distance is zero (thus the tracker pays a fixed cost for any nonzero motion). We begin by studying arbitrary metric spaces with the “pay if you move” metric of Yi and Zhang (In: Proceedings of the 20th annual ACM-SIAM symposium on discrete algorithms (SODA), pp. 1098–1107. ACM Press, New York, [ 2009 ]) described above and describe a natural randomized algorithm that achieves a O (log b Δ )-competitive ratio, where b Δ =max x ∈ X \| B Δ ( x )\| is the maximum number of points appearing in any ball of radius Δ. We show that this bound is tight. We then focus on the metric space ℤ with natural families of monotone cost functions c ( x )= x p for some p ≥0. We consider both the expansive case ( p ≥1) and the contractive case ( p <1), and show that the natural lazy algorithm performs well in the expansive case. In the contractive case, we introduce and analyze a novel deterministic algorithm that achieves a constant competitive ratio depending only on p . Finally, we observe that by slightly relaxing the guarantee provided by the tracker, one can obtain natural analogues of these algorithms that work in continuous metric spaces.
Author	Chen, Sixia Russell, Alexander
Author_xml	– sequence: 1 givenname: Sixia surname: Chen fullname: Chen, Sixia email: sxchen@engr.uconn.edu organization: Department of Computer Science and Engineering, University of Connecticut – sequence: 2 givenname: Alexander surname: Russell fullname: Russell, Alexander organization: Department of Computer Science and Engineering, University of Connecticut
BackLink	http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=28568829$$DView record in Pascal Francis
BookMark	eNp9kE1LAzEQhoNUsK3-AG970GN08p0cpWgVKj1YzyHNJnVrmy1JPfjvTVnx6GkYeJ5h3neCRqlPAaFrAncEQN0XAC4YBkKxkdJgfYbGhDOKQXAyQmMgSmMuibpAk1K2UEFl5BjdLNOuS6F5Dcfc-WaVnf_s0qZxqW3e9n1__KjbJTqPblfC1e-covenx9XsGS-W85fZwwJ7quCInZNRQGBciADSrXVgrWtFVMBoFBoYC5QzDrE1Xom11DSaNdfGs_qxiYRN0e1w9-CKd7uYXfJdsYfc7V3-tlQLqTU1lSMD53NfSg7xDyFgT3XYoQ5bU9pTHVZXhw5OqWzahGy3_VdONc4_0g8aEWIt
Cites_doi	10.1137/1.9781611973068.119 10.1145/1921659.1921667 10.1016/0196-6774(91)90041-V 10.1007/11830924_12 10.1111/j.2517-6161.1958.tb00294.x
ContentType	Journal Article
Copyright	Springer Science+Business Media, LLC 2012 2015 INIST-CNRS
Copyright_xml	– notice: Springer Science+Business Media, LLC 2012 – notice: 2015 INIST-CNRS
DBID	AAYXX CITATION IQODW
DOI	10.1007/s00453-012-9669-8
DatabaseName	CrossRef Pascal-Francis
DatabaseTitle	CrossRef
DatabaseTitleList
DeliveryMethod	fulltext_linktorsrc
Discipline	Computer Science Applied Sciences
EISSN	1432-0541
EndPage	151
ExternalDocumentID	28568829 10_1007_s00453_012_9669_8
GroupedDBID	-4Z -59 -5G -BR -EM -Y2 -~C -~X .86 .DC .VR 06D 0R~ 0VY 199 1N0 1SB 203 23M 28- 2J2 2JN 2JY 2KG 2KM 2LR 2P1 2VQ 2~H 30V 4.4 406 408 409 40D 40E 5GY 5QI 5VS 67Z 6NX 78A 8TC 8UJ 95- 95. 95~ 96X AAAVM AABHQ AACDK AAHNG AAIAL AAJBT AAJKR AANZL AAOBN AARHV AARTL AASML AATNV AATVU AAUYE AAWCG AAYIU AAYQN AAYTO AAYZH ABAKF ABBBX ABBXA ABDPE ABDZT ABECU ABFSI ABFTV ABHLI ABHQN ABJNI ABJOX ABKCH ABKTR ABLJU ABMNI ABMQK ABNWP ABQBU ABQSL ABSXP ABTAH ABTEG ABTHY ABTKH ABTMW ABULA ABWNU ABXPI ACAOD ACBXY ACDTI ACGFS ACHSB ACHXU ACKNC ACMDZ ACMLO ACOKC ACOMO ACPIV ACZOJ ADHHG ADHIR ADIMF ADINQ ADKNI ADKPE ADRFC ADTPH ADURQ ADYFF ADZKW AEBTG AEFIE AEFQL AEGAL AEGNC AEJHL AEJRE AEKMD AEMSY AENEX AEOHA AEPYU AESKC AETLH AEVLU AEXYK AFBBN AFEXP AFGCZ AFLOW AFQWF AFWTZ AFZKB AGAYW AGDGC AGGDS AGJBK AGMZJ AGQEE AGQMX AGRTI AGWIL AGWZB AGYKE AHAVH AHBYD AHKAY AHSBF AHYZX AI. AIAKS AIGIU AIIXL AILAN AITGF AJBLW AJRNO AJZVZ ALMA_UNASSIGNED_HOLDINGS ALWAN AMKLP AMXSW AMYLF AMYQR AOCGG ARMRJ ASPBG AVWKF AXYYD AYJHY AZFZN B-. BA0 BBWZM BDATZ BGNMA BSONS CAG COF CS3 CSCUP DDRTE DL5 DNIVK DPUIP E.L EBLON EBS EIOEI EJD ESBYG FEDTE FERAY FFXSO FIGPU FINBP FNLPD FRRFC FSGXE FWDCC GGCAI GGRSB GJIRD GNWQR GQ6 GQ7 GQ8 GXS H13 HF~ HG5 HG6 HMJXF HQYDN HRMNR HVGLF HZ~ H~9 I09 IHE IJ- IKXTQ ITM IWAJR IXC IZIGR IZQ I~X I~Z J-C J0Z JBSCW JCJTX JZLTJ KDC KOV KOW LAS LLZTM M4Y MA- N2Q N9A NB0 NDZJH NPVJJ NQJWS NU0 O9- O93 O9G O9I O9J OAM P19 P9O PF- PT4 PT5 QOK QOS R4E R89 R9I RHV RIG RNI RNS ROL RPX RSV RZK S16 S1Z S26 S27 S28 S3B SAP SCJ SCLPG SCO SDH SDM SHX SISQX SJYHP SNE SNPRN SNX SOHCF SOJ SPISZ SRMVM SSLCW STPWE SZN T13 T16 TN5 TSG TSK TSV TUC U2A UG4 UOJIU UQL UTJUX UZXMN VC2 VFIZW VH1 VXZ W23 W48 WK8 YLTOR Z45 Z7X Z83 Z88 Z8R Z8W Z92 ZMTXR ZY4 ~EX AAPKM AAYXX ABBRH ABDBE ABFSG ABRTQ ACSTC ADHKG AEZWR AFDZB AFHIU AFOHR AGQPQ AHPBZ AHWEU AIXLP ATHPR AYFIA CITATION IQODW
ID	FETCH-LOGICAL-c270t-aa6f50e3455e06ab8e3dad5f7032f58033e24340fd9c75b682f9b489c36699f13
IEDL.DBID	RSV
ISICitedReferencesCount	0
ISICitedReferencesURI	http://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=Summon&SrcAuth=ProQuest&DestLinkType=CitingArticles&DestApp=WOS_CPL&KeyUT=000329093300007&url=https%3A%2F%2Fcvtisr.summon.serialssolutions.com%2F%23%21%2Fsearch%3Fho%3Df%26include.ft.matches%3Dt%26l%3Dnull%26q%3D
ISSN	0178-4617
IngestDate	Wed Apr 02 07:25:10 EDT 2025 Sat Nov 29 03:45:25 EST 2025 Fri Feb 21 02:40:21 EST 2025
IsPeerReviewed	true
IsScholarly	true
Issue	1
Keywords	Online algorithms Randomized algorithms On line Tracking Proximity Metric space Fixed cost Competitiveness Algorithmics Online algorithm Randomized algorithm Time varying system Smoothing Metric Deterministic algorithms
Language	English
License	http://www.springer.com/tdm CC BY 4.0
LinkModel	DirectLink
MergedId	FETCHMERGED-LOGICAL-c270t-aa6f50e3455e06ab8e3dad5f7032f58033e24340fd9c75b682f9b489c36699f13
PageCount	19
ParticipantIDs	pascalfrancis_primary_28568829 crossref_primary_10_1007_s00453_012_9669_8 springer_journals_10_1007_s00453_012_9669_8
PublicationCentury	2000
PublicationDate	20140100 2014-1-00 2014
PublicationDateYYYYMMDD	2014-01-01
PublicationDate_xml	– month: 1 year: 2014 text: 20140100
PublicationDecade	2010
PublicationPlace	Boston
PublicationPlace_xml	– name: Boston – name: Heidelberg
PublicationTitle	Algorithmica
PublicationTitleAbbrev	Algorithmica
PublicationYear	2014
Publisher	Springer US Springer
Publisher_xml	– name: Springer US – name: Springer
References	Smith (CR9) 1958; 20 Cormode, Garofalakis, Muthukrishnan, Rastogi (CR3) 2005 Cormode, Garofalakis (CR2) 2005 Yi, Zhang (CR10) 2009 Davis, Edmonds, Impagliazzo (CR5) 2006 Fiat, Karp, Luby, McGeoch, Sleator, Young (CR6) 1991; 12 Cormode, Muthukrishnan, Yi (CR4) 2011; 7 CR8 Keralapura, Cormode, Ramamirtham (CR7) 2006 Bienkowski, Schmid (CR1) 2010 9669_CR8 G. Cormode (9669_CR2) 2005 A. Fiat (9669_CR6) 1991; 12 M. Bienkowski (9669_CR1) 2010 G. Cormode (9669_CR4) 2011; 7 W.L. Smith (9669_CR9) 1958; 20 G. Cormode (9669_CR3) 2005 R. Keralapura (9669_CR7) 2006 S. Davis (9669_CR5) 2006 K. Yi (9669_CR10) 2009
References_xml	– start-page: 104 year: 2006 end-page: 115 ident: CR5 article-title: Online algorithms to minimize resource reallocations and network communication publication-title: Proceedings of the 9th Int. Workshop on Approximation Algorithm for Combinatorial Optimization (APPROX) – start-page: 13 year: 2005 end-page: 24 ident: CR2 article-title: Sketching streams through the net: Distributed approximate query tracking publication-title: Proceedings of the 31st Int. Conference on Very Large Data Bases (VLDB) – start-page: 359 year: 2010 end-page: 370 ident: CR1 article-title: Online function tracking with generalized penalties publication-title: Proceedings of the 12th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT) – start-page: 1098 year: 2009 end-page: 1107 ident: CR10 article-title: Multi-dimensional online tracking publication-title: Proceedings of the 20th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA) doi: 10.1137/1.9781611973068.119 – volume: 7 start-page: 1 issue: 2 year: 2011 end-page: 21 ident: CR4 article-title: Algorithms for distributed functional monitoring publication-title: ACM Trans. Algorithms doi: 10.1145/1921659.1921667 – ident: CR8 – volume: 20 start-page: 243 issue: 2 year: 1958 end-page: 302 ident: CR9 article-title: Renewal theory and its ramifications publication-title: J. R. Stat. Soc., Ser. B, Stat. Methodol. – start-page: 289 year: 2006 end-page: 300 ident: CR7 article-title: Communication-efficient distributed monitoring of thresholded counts publication-title: Proceedings of ACM Special Interest Group on Management of Data (SIGMOD) – volume: 12 start-page: 658 issue: 4 year: 1991 end-page: 699 ident: CR6 article-title: Competitive paging algorithms publication-title: J. Algorithms doi: 10.1016/0196-6774(91)90041-V – start-page: 25 year: 2005 end-page: 36 ident: CR3 article-title: Holistic aggregates in a networked world: Distributed tracking of approximate quantiles publication-title: Proceedings of ACM Special Interest Group on Management of Data (SIGMOD) – start-page: 13 volume-title: Proceedings of the 31st Int. Conference on Very Large Data Bases (VLDB) year: 2005 ident: 9669_CR2 – volume: 12 start-page: 658 issue: 4 year: 1991 ident: 9669_CR6 publication-title: J. Algorithms doi: 10.1016/0196-6774(91)90041-V – start-page: 25 volume-title: Proceedings of ACM Special Interest Group on Management of Data (SIGMOD) year: 2005 ident: 9669_CR3 – start-page: 359 volume-title: Proceedings of the 12th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT) year: 2010 ident: 9669_CR1 – start-page: 104 volume-title: Proceedings of the 9th Int. Workshop on Approximation Algorithm for Combinatorial Optimization (APPROX) year: 2006 ident: 9669_CR5 doi: 10.1007/11830924_12 – start-page: 289 volume-title: Proceedings of ACM Special Interest Group on Management of Data (SIGMOD) year: 2006 ident: 9669_CR7 – start-page: 1098 volume-title: Proceedings of the 20th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA) year: 2009 ident: 9669_CR10 doi: 10.1137/1.9781611973068.119 – volume: 20 start-page: 243 issue: 2 year: 1958 ident: 9669_CR9 publication-title: J. R. Stat. Soc., Ser. B, Stat. Methodol. doi: 10.1111/j.2517-6161.1958.tb00294.x – ident: 9669_CR8 – volume: 7 start-page: 1 issue: 2 year: 2011 ident: 9669_CR4 publication-title: ACM Trans. Algorithms doi: 10.1145/1921659.1921667
SSID	ssj0012796
Score	1.9925623
Snippet	We consider the online smoothing problem , in which a tracker is required to maintain distance no more than Δ≥0 from a time-varying signal f while minimizing...
SourceID	pascalfrancis crossref springer
SourceType	Index Database Publisher
StartPage	133
SubjectTerms	Algorithm Analysis and Problem Complexity Algorithmics. Computability. Computer arithmetics Algorithms Applied sciences Computer Science Computer science; control theory; systems Computer Systems Organization and Communication Networks Data Structures and Information Theory Exact sciences and technology Mathematics of Computing Theoretical computing Theory of Computation
Title	Online Metric Tracking and Smoothing
URI	https://link.springer.com/article/10.1007/s00453-012-9669-8
Volume	68
WOSCitedRecordID	wos000329093300007&url=https%3A%2F%2Fcvtisr.summon.serialssolutions.com%2F%23%21%2Fsearch%3Fho%3Df%26include.ft.matches%3Dt%26l%3Dnull%26q%3D
hasFullText	1
inHoldings	1
isFullTextHit
isPrint
journalDatabaseRights	– providerCode: PRVAVX databaseName: Springer LINK customDbUrl: eissn: 1432-0541 dateEnd: 99991231 omitProxy: false ssIdentifier: ssj0012796 issn: 0178-4617 databaseCode: RSV dateStart: 19970101 isFulltext: true titleUrlDefault: https://link.springer.com/search?facet-content-type=%22Journal%22 providerName: Springer Nature
link	http://cvtisr.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwnV1LSwMxEB60ehDE-sT6KHvoSQls89hNjiIWLxaxKr0tSTYBD7alW_39TvYFRT3ocWE3ZCaZnS-Z5PsABqlXNk1jTaQSlHDvPTHMa-KkswlFDG2cLsUm0vFYTqfqsb7HXTSn3ZuSZPmnbi-7BfQRzv7QwCipiNyELcx2Mug1PE1e29IBTUtRriA7Tzjm56aU-VMTa8lod6EL9IuvBC2-VUbLhDPq_qur-7BX48voppoQB7DhZofQbbQbojqUj2BQcYxGD0FRy0aYsmzYNI_0LI8m73McP3w6hpfR3fPtPakVE4ilabwiWidexI5xIVycaCMdy3UuPIY19ULGjDnKGY99jiMkTCKpV4ZLZRl2U_khO4HObD5zpxDh0sbkuUWEIigXPtDwxRzXbtYNvWFG9OCqcV22qIgxspYCubQ_Q_uzYH8me9Bfc277BZUiQYyvenDdeDKrg6j4vbmzP719DjuIcni1b3IBndXyw13Ctv1cvRXLfjl5vgB8Nrz-
linkProvider	Springer Nature
linkToHtml	http://cvtisr.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwnV1LSwMxEB60CgpifWJ91D30pAS2eewmRxGlYlvEVultSbIJeLAt3ervN9kXFPWgx4XdkJlkdr5kku8D6MRW6DgOJeKCYUSttUgRK5HhRkfYYWhlZC42EQ-HfDIRT-U97qw67V6VJPM_dX3ZzaMPf_YHe0ZJgfg6bFCXsDxh_vPotS4d4DgX5fKy84i6_FyVMn9qYiUZ7cxl5vxiC0GLb5XRPOHcN__V1T3YLfFlcFNMiH1YM9MDaFbaDUEZyofQKThGg4FX1NKBS1nab5oHcpoGo_eZGz_3dAQv93fj2x4qFROQxnG4RFJGloWGUMZMGEnFDUllyqwLa2wZDwkxmBIa2tSNEFMRx1YoyoUmrpvCdskxNKazqTmBwC1tVJpqh1AYpsx6Gr6QurWbNl2riGItuKpcl8wLYoykpkDO7U-c_Ym3P-EtaK84t_4CcxY5jC9acF15MimDKPu9udM_vX0JW73xoJ_0H4aPZ7DtEA8t9lDOobFcfJgL2NSfy7ds0c4n0hdjQL_i
linkToPdf	http://cvtisr.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwpV1LSwMxEB60ighifWJ91D30pIRu89hNjqIWRS2FqvS2ZLMJeHBbuqu_32RfUNSDeFzIhmSSYb5kJt8H0AuNUGHoS8QFw4gaY1BMjESaaxVgi6FjLQuxiXA04tOpGFc6p1ld7V6nJMs3DY6lKc3788T0m4dvDom4OiDs2CUF4quwRl0dvTuuT16bNAIOC4EuJ0GPqI3VdVrzpy6WAtPWXGbWRqYUt_iWJS2Cz7D972HvwHaFO72rcqPswopO96Bdazp4lYvvQ6_kHvWenNKW8mwoU-4y3ZNp4k3eZ3Zd7dcBvAxvn6_vUKWkgBQO_RxJGRjma0IZ034gY65JIhNmrLtjw7hPiMaUUN8kduVYHHBsREy5UMQOU5gBOYRWOkv1EXj2yBMnibLIhWHKjKPn863pqdIDE5OYdeCiNmM0LwkzooYauZh_ZOcfuflHvAPdJUM3f2DOAov9RQcua6tGlXNlv3d3_KfW57AxvhlGj_ejhxPYtECIllcrp9DKFx_6DNbVZ_6WLbrFnvoCkvbIxg
openUrl	ctx_ver=Z39.88-2004&ctx_enc=info%3Aofi%2Fenc%3AUTF-8&rfr_id=info%3Asid%2Fsummon.serialssolutions.com&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Online+Metric+Tracking+and+Smoothing&rft.jtitle=Algorithmica&rft.au=CHEN%2C+Sixia&rft.au=RUSSELL%2C+Alexander&rft.date=2014&rft.pub=Springer&rft.issn=0178-4617&rft.volume=68&rft.issue=1&rft.spage=133&rft.epage=151&rft_id=info:doi/10.1007%2Fs00453-012-9669-8&rft.externalDBID=n%2Fa&rft.externalDocID=28568829
thumbnail_l	http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/lc.gif&issn=0178-4617&client=summon
thumbnail_m	http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/mc.gif&issn=0178-4617&client=summon
thumbnail_s	http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/sc.gif&issn=0178-4617&client=summon