An Abstraction-Free Method for Multirobot Temporal Logic Optimal Control Synthesis

The majority of existing linear temporal logic (LTL) planning methods rely on the construction of a discrete product automaton, which combines a discrete abstraction of robot mobility and a Büchi automaton that captures the LTL specification. Representing this product automaton as a graph and using...

Full description

Saved in:

Bibliographic Details
Published in:	IEEE transactions on robotics Vol. 37; no. 5; pp. 1487 - 1507
Main Authors:	Luo, Xusheng, Kantaros, Yiannis, Zavlanos, Michael M.
Format:	Journal Article
Language:	English
Published:	New York IEEE 01.10.2021 The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:	Acceleration Algorithms Automata Bias Data storage Formal methods in robotics and automation Graphical representations Heuristic algorithms motion and path planning Multiple robots Navigation Optimal control optimization and optimal control path planning for multiple mobile robots or agents Planning Sampling Sampling methods Shortest-path problems Synthesis Task analysis Temporal logic Trees
ISSN:	1552-3098, 1941-0468
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Abstract	The majority of existing linear temporal logic (LTL) planning methods rely on the construction of a discrete product automaton, which combines a discrete abstraction of robot mobility and a Büchi automaton that captures the LTL specification. Representing this product automaton as a graph and using graph search techniques, optimal plans that satisfy the LTL task can be synthesized. However, constructing expressive discrete abstractions makes the synthesis problem computationally intractable. In this article, we propose a new sampling-based LTL planning algorithm that does not require any discrete abstraction of robot mobility. Instead, it incrementally builds trees that explore the product state-space, until a maximum number of iterations is reached or a feasible plan is found. The use of trees makes data storage and graph search tractable, which significantly increases the scalability of our algorithm. To accelerate the construction of feasible plans, we introduce bias in the sampling process, which is guided by transitions in the Büchi automaton that belong to the shortest path to the accepting states. We show that our planning algorithm, with and without bias, is probabilistically complete and asymptotically optimal. Finally, we present numerical experiments showing that our method outperforms relevant temporal logic planning methods.
AbstractList	The majority of existing linear temporal logic (LTL) planning methods rely on the construction of a discrete product automaton, which combines a discrete abstraction of robot mobility and a Büchi automaton that captures the LTL specification. Representing this product automaton as a graph and using graph search techniques, optimal plans that satisfy the LTL task can be synthesized. However, constructing expressive discrete abstractions makes the synthesis problem computationally intractable. In this article, we propose a new sampling-based LTL planning algorithm that does not require any discrete abstraction of robot mobility. Instead, it incrementally builds trees that explore the product state-space, until a maximum number of iterations is reached or a feasible plan is found. The use of trees makes data storage and graph search tractable, which significantly increases the scalability of our algorithm. To accelerate the construction of feasible plans, we introduce bias in the sampling process, which is guided by transitions in the Büchi automaton that belong to the shortest path to the accepting states. We show that our planning algorithm, with and without bias, is probabilistically complete and asymptotically optimal. Finally, we present numerical experiments showing that our method outperforms relevant temporal logic planning methods.
Author	Kantaros, Yiannis Luo, Xusheng Zavlanos, Michael M.
Author_xml	– sequence: 1 givenname: Xusheng orcidid: 0000-0003-4342-7234 surname: Luo fullname: Luo, Xusheng email: xusheng.luo@duke.edu organization: Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA – sequence: 2 givenname: Yiannis orcidid: 0000-0002-0257-7378 surname: Kantaros fullname: Kantaros, Yiannis email: kantaros@seas.upenn.edu organization: Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA – sequence: 3 givenname: Michael M. orcidid: 0000-0003-1748-8228 surname: Zavlanos fullname: Zavlanos, Michael M. email: michael.zavlanos@duke.edu organization: Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA
BookMark	eNp9kM1LAzEQxYNUsFbvgpeA56352GSTYylWhZZCreeQ3SY2ZbtZk_TQ_96UFg8ePM08eG_e8LsFg853BoAHjMYYI_m8Xi3HBBE8pohjKegVGGJZ4gKVXAzyzhgpKJLiBtzGuEOIlBLRIVhNOjipYwq6Sc53xSwYAxcmbf0GWh_g4tAmF3ztE1ybfe-DbuHcf7kGLvvk9llNfZeCb-HHsUtbE128A9dWt9HcX-YIfM5e1tO3Yr58fZ9O5kVDJE6FsJzWJZOIkLIS3FhksGRGW2spF5taN8hujKQM4UprxiuaBeVMM5EtjaQj8HS-2wf_fTAxqZ0_hC5XKsIqQSgrWZVd6Oxqgo8xGKv6kP8OR4WROpFTmZw6kVMXcjnC_0Qal_QJT8bk2v-Cj-egM8b89kgqWIUq-gMMcX0n
CODEN	ITREAE
CitedBy_id	crossref_primary_10_1177_02783649241278372 crossref_primary_10_1109_LRA_2021_3138766 crossref_primary_10_1109_TRO_2022_3144073 crossref_primary_10_1016_j_arcontrol_2022_03_004 crossref_primary_10_1109_LRA_2025_3598648 crossref_primary_10_1109_TRO_2023_3291463 crossref_primary_10_1016_j_ifacol_2023_10_959 crossref_primary_10_1109_LRA_2024_3401166 crossref_primary_10_34133_research_0337 crossref_primary_10_1109_TITS_2025_3582585 crossref_primary_10_1109_TRO_2021_3130794 crossref_primary_10_1109_TRO_2025_3598139 crossref_primary_10_1016_j_arcontrol_2024_100940 crossref_primary_10_1109_LRA_2023_3246844 crossref_primary_10_1109_LRA_2024_3412589 crossref_primary_10_1016_j_automatica_2023_111377 crossref_primary_10_1016_j_automatica_2024_112105 crossref_primary_10_1109_TAC_2025_3550850 crossref_primary_10_1177_02783649251315758 crossref_primary_10_1109_TRO_2024_3392079 crossref_primary_10_1016_j_cja_2025_103823 crossref_primary_10_1109_TIE_2023_3299048 crossref_primary_10_1109_TASE_2025_3553498 crossref_primary_10_1109_TRO_2022_3181948 crossref_primary_10_1145_3665499 crossref_primary_10_1109_LRA_2024_3408486
Cites_doi	10.1109/CDC.2017.8263808 10.1109/ROBOT.2000.844730 10.1109/CDC40024.2019.9030087 10.1145/3055004.3055021 10.1177/0278364914546174 10.1109/CDC.2011.6160740 10.1007/978-3-319-60916-4_20 10.1177/0278364911406761 10.1109/CDC.2004.1428674 10.1002/rnc.1715 10.1109/TSMC.2017.2670643 10.1126/scirobotics.aay6276 10.1016/j.ejcon.2018.10.002 10.1109/ICRA.2015.7139022 10.1109/CCA.2016.7587878 10.1109/ICRA.2014.6907641 10.1109/TRO.2005.851359 10.1109/TRO.2018.2861901 10.1177/0278364919856695 10.1109/ROBOT.2010.5509503 10.1177/0278364920913922 10.1177/0278364913487931 10.1109/JPROC.2018.2849003 10.1109/TRO.2011.2163434 10.1109/TAC.2018.2853558 10.1109/70.508439 10.1109/TRO.2009.2030225 10.1177/0278364911417911 10.1145/3055004.3055027 10.1109/IROS.2003.1249705 10.1080/00949655.2015.1081907 10.1109/CDC.2018.8618922 10.1109/ICRA.2017.7989036 10.1109/ICCPS.2018.00024 10.1007/978-3-540-78800-3_24 10.2168/LMCS-2(5:5)2006 10.1109/TAC.2007.914952 10.1007/11730637_27 10.1109/TRO.2019.2897865 10.1109/TAC.2016.2626400 10.1109/ICRA40945.2020.9196553 10.1109/ROBOT.2005.1570410 10.1145/116873.116880 10.1007/978-3-642-55146-8_24 10.1109/TRO.2009.2035776 10.1109/TRO.2016.2593045 10.1109/IROS.2011.6048842 10.1007/s10514-015-9519-z 10.1109/ACSSC.2015.7421315 10.1017/CBO9780511546877
ContentType	Journal Article
Copyright	Copyright The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 2021
Copyright_xml	– notice: Copyright The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 2021
DBID	97E RIA RIE AAYXX CITATION 7SC 7SP 7TB 8FD FR3 JQ2 L7M L~C L~D
DOI	10.1109/TRO.2021.3061983
DatabaseName	IEEE All-Society Periodicals Package (ASPP) 2005-present IEEE All-Society Periodicals Package (ASPP) 1998-Present IEEE Electronic Library (IEL) CrossRef Computer and Information Systems Abstracts Electronics & Communications Abstracts Mechanical & Transportation Engineering Abstracts Technology Research Database Engineering Research Database ProQuest Computer Science Collection Advanced Technologies Database with Aerospace Computer and Information Systems Abstracts Academic Computer and Information Systems Abstracts Professional
DatabaseTitle	CrossRef Technology Research Database Computer and Information Systems Abstracts – Academic Mechanical & Transportation Engineering Abstracts Electronics & Communications Abstracts ProQuest Computer Science Collection Computer and Information Systems Abstracts Engineering Research Database Advanced Technologies Database with Aerospace Computer and Information Systems Abstracts Professional
DatabaseTitleList	Technology Research Database
Database_xml	– sequence: 1 dbid: RIE name: IEEE Electronic Library (IEL) url: https://ieeexplore.ieee.org/ sourceTypes: Publisher
DeliveryMethod	fulltext_linktorsrc
Discipline	Engineering
EISSN	1941-0468
EndPage	1507
ExternalDocumentID	10_1109_TRO_2021_3061983 9385707
Genre	orig-research
GrantInformation_xml	– fundername: ONR grantid: N00014-18-1-2374 funderid: 10.13039/100000006 – fundername: Air Force Office of Scientific Research; AFOSR grantid: FA9550-19-1-0169 funderid: 10.13039/100000181
GroupedDBID	.DC 0R~ 29I 4.4 5GY 5VS 6IK 97E AAJGR AARMG AASAJ AAWTH ABAZT ABQJQ ABVLG ACGFO ACIWK AENEX AETIX AGQYO AGSQL AHBIQ AIBXA AKJIK AKQYR ALMA_UNASSIGNED_HOLDINGS ATWAV BEFXN BFFAM BGNUA BKEBE BPEOZ CS3 DU5 EBS EJD F5P HZ~ H~9 IFIPE IPLJI JAVBF LAI M43 MS~ O9- OCL P2P PQQKQ RIA RIE RNS VJK AAYXX CITATION 7SC 7SP 7TB 8FD FR3 JQ2 L7M L~C L~D
ID	FETCH-LOGICAL-c291t-8f63b4590224786ef0e195eafff368dbac0fde935017aa5673e93365a58fffc93
IEDL.DBID	RIE
ISICitedReferencesCount	40
ISICitedReferencesURI	http://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=Summon&SrcAuth=ProQuest&DestLinkType=CitingArticles&DestApp=WOS_CPL&KeyUT=000702631200013&url=https%3A%2F%2Fcvtisr.summon.serialssolutions.com%2F%23%21%2Fsearch%3Fho%3Df%26include.ft.matches%3Dt%26l%3Dnull%26q%3D
ISSN	1552-3098
IngestDate	Sun Nov 09 06:14:23 EST 2025 Tue Nov 18 22:26:35 EST 2025 Sat Nov 29 01:47:27 EST 2025 Wed Aug 27 02:26:04 EDT 2025
IsPeerReviewed	true
IsScholarly	true
Issue	5
Language	English
License	https://ieeexplore.ieee.org/Xplorehelp/downloads/license-information/IEEE.html
LinkModel	DirectLink
MergedId	FETCHMERGED-LOGICAL-c291t-8f63b4590224786ef0e195eafff368dbac0fde935017aa5673e93365a58fffc93
Notes	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14
ORCID	0000-0003-1748-8228 0000-0003-4342-7234 0000-0002-0257-7378
PQID	2578235457
PQPubID	27625
PageCount	21
ParticipantIDs	crossref_primary_10_1109_TRO_2021_3061983 ieee_primary_9385707 proquest_journals_2578235457 crossref_citationtrail_10_1109_TRO_2021_3061983
PublicationCentury	2000
PublicationDate	2021-Oct. 2021-10-00 20211001
PublicationDateYYYYMMDD	2021-10-01
PublicationDate_xml	– month: 10 year: 2021 text: 2021-Oct.
PublicationDecade	2020
PublicationPlace	New York
PublicationPlace_xml	– name: New York
PublicationTitle	IEEE transactions on robotics
PublicationTitleAbbrev	TRO
PublicationYear	2021
Publisher	IEEE The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher_xml	– name: IEEE – name: The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
References	ref57 ref12 ref59 ref15 ref58 ref14 ref53 ref52 ref54 ref10 ref17 ref19 ref18 karaman (ref40) 0 ref51 ref50 ref46 ref48 baier (ref11) 2008 ref47 ref44 ref43 kreveld (ref55) 2000 vardi (ref45) 0 ref49 gastin (ref56) 0 ref8 clarke (ref16) 1999 ref7 ref9 ref4 ref3 ref6 ref5 ref35 ref34 ref37 ref36 ref31 ref30 ref33 ref32 ref1 ref39 ref38 choset (ref2) 2005 ref24 ref23 ref26 vasile (ref42) 0 ref25 ref20 ref22 ref21 rudin (ref60) 2006 ref28 ref27 ref29 kress-gazit (ref13) 0 karaman (ref41) 0 ref61
References_xml	– ident: ref38 doi: 10.1109/CDC.2017.8263808 – ident: ref4 doi: 10.1109/ROBOT.2000.844730 – ident: ref32 doi: 10.1109/CDC40024.2019.9030087 – ident: ref35 doi: 10.1145/3055004.3055021 – start-page: 3116 year: 0 ident: ref13 publication-title: Proc IEEE Int Conf Robot Automat – ident: ref18 doi: 10.1177/0278364914546174 – ident: ref14 doi: 10.1109/CDC.2011.6160740 – ident: ref57 doi: 10.1007/978-3-319-60916-4_20 – ident: ref6 doi: 10.1177/0278364911406761 – ident: ref23 doi: 10.1109/CDC.2004.1428674 – ident: ref36 doi: 10.1002/rnc.1715 – ident: ref54 doi: 10.1109/TSMC.2017.2670643 – ident: ref51 doi: 10.1126/scirobotics.aay6276 – ident: ref26 doi: 10.1016/j.ejcon.2018.10.002 – ident: ref44 doi: 10.1109/ICRA.2015.7139022 – ident: ref3 doi: 10.1109/CCA.2016.7587878 – ident: ref37 doi: 10.1109/ICRA.2014.6907641 – ident: ref24 doi: 10.1109/TRO.2005.851359 – start-page: 735 year: 0 ident: ref41 article-title: Sampling-based algorithms for optimal motion planning with deterministic $\mu$-calculus specifications publication-title: Proc Amer Control Conf – ident: ref34 doi: 10.1109/TRO.2018.2861901 – ident: ref48 doi: 10.1177/0278364919856695 – start-page: 332 year: 0 ident: ref45 article-title: An automata-theoretic approach to automatic program verification publication-title: Proc 1st Symp Log Comput Sci – ident: ref43 doi: 10.1109/ROBOT.2010.5509503 – ident: ref31 doi: 10.1177/0278364920913922 – ident: ref20 doi: 10.1177/0278364913487931 – ident: ref39 doi: 10.1109/JPROC.2018.2849003 – ident: ref15 doi: 10.1109/TRO.2011.2163434 – ident: ref29 doi: 10.1109/TAC.2018.2853558 – ident: ref5 doi: 10.1109/70.508439 – year: 2006 ident: ref60 publication-title: Real and Complex Analysis – ident: ref12 doi: 10.1109/TRO.2009.2030225 – ident: ref17 doi: 10.1177/0278364911417911 – ident: ref28 doi: 10.1145/3055004.3055027 – ident: ref22 doi: 10.1109/IROS.2003.1249705 – ident: ref49 doi: 10.1080/00949655.2015.1081907 – ident: ref30 doi: 10.1109/CDC.2018.8618922 – start-page: 2222 year: 0 ident: ref40 article-title: Sampling-based motion planning with deterministic $\mu$-calculus specifications publication-title: Proc 48 th IEEE Conf Decis Control Held Jointly 2009 28th Chin Control Conf – ident: ref8 doi: 10.1109/ICRA.2017.7989036 – ident: ref33 doi: 10.1109/ICCPS.2018.00024 – ident: ref58 doi: 10.1007/978-3-540-78800-3_24 – year: 2000 ident: ref55 publication-title: Computational Geometry Algorithms and Applications – year: 1999 ident: ref16 publication-title: Model checking – ident: ref59 doi: 10.2168/LMCS-2(5:5)2006 – start-page: 53 year: 0 ident: ref56 article-title: Fast LTL to Büchi automata translation publication-title: Proc Int Conf Comput Aided Verification – ident: ref46 doi: 10.1109/TAC.2007.914952 – ident: ref25 doi: 10.1007/11730637_27 – ident: ref52 doi: 10.1109/TRO.2019.2897865 – ident: ref9 doi: 10.1109/TAC.2016.2626400 – ident: ref47 doi: 10.1109/ICRA40945.2020.9196553 – ident: ref7 doi: 10.1109/ROBOT.2005.1570410 – start-page: 4817 year: 0 ident: ref42 article-title: Sampling-based temporal logic path planning publication-title: Proc IEEE/RSJ Int Conf Intell Robots Syst – year: 2005 ident: ref2 publication-title: Principles of Robot Motion Theory Algorithms and Implementations – ident: ref61 doi: 10.1145/116873.116880 – ident: ref21 doi: 10.1007/978-3-642-55146-8_24 – ident: ref19 doi: 10.1109/TRO.2009.2035776 – ident: ref50 doi: 10.1109/TRO.2016.2593045 – ident: ref53 doi: 10.1109/IROS.2011.6048842 – ident: ref10 doi: 10.1007/s10514-015-9519-z – ident: ref27 doi: 10.1109/ACSSC.2015.7421315 – ident: ref1 doi: 10.1017/CBO9780511546877 – year: 2008 ident: ref11 publication-title: Principles of Model Checking
SSID	ssj0024903
Score	2.5769875
Snippet	The majority of existing linear temporal logic (LTL) planning methods rely on the construction of a discrete product automaton, which combines a discrete...
SourceID	proquest crossref ieee
SourceType	Aggregation Database Enrichment Source Index Database Publisher
StartPage	1487
SubjectTerms	Acceleration Algorithms Automata Bias Data storage Formal methods in robotics and automation Graphical representations Heuristic algorithms motion and path planning Multiple robots Navigation Optimal control optimization and optimal control path planning for multiple mobile robots or agents Planning Sampling Sampling methods Shortest-path problems Synthesis Task analysis Temporal logic Trees
Title	An Abstraction-Free Method for Multirobot Temporal Logic Optimal Control Synthesis
URI	https://ieeexplore.ieee.org/document/9385707 https://www.proquest.com/docview/2578235457
Volume	37
WOSCitedRecordID	wos000702631200013&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: PRVIEE databaseName: IEEE Electronic Library (IEL) customDbUrl: eissn: 1941-0468 dateEnd: 99991231 omitProxy: false ssIdentifier: ssj0024903 issn: 1552-3098 databaseCode: RIE dateStart: 20040101 isFulltext: true titleUrlDefault: https://ieeexplore.ieee.org/ providerName: IEEE
link	http://cvtisr.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwlV3dS8MwED_m8EEf_JridEoefBHs1jZdk3scw-GDbqJTfCtpmoAwW9mH4H9vknZTUQTfGriUkmsud7m73w_gTLMAmQwCL2WovSjLArOl4sgzdhAFMlTK8ZA9XrPhkD894W0NLla9MEopV3ym2vbR5fKzQi7sVVkHqYVjZ2uwxhgre7U-cfXQsSBbRDGP-siXKUkfO-O7kQkEw6Bt3GMTY9NvR5DjVPlhiN3pMtj-33ftwFblRZJeqfZdqKl8Dza_YAs24K6Xk15qLzJc54I3mCpFbhxfNDGOKnGdt9MiLeZkXMJTTYglXpZkZKzIixn1yyp2cv-eGy9x9jzbh4fB5bh_5VUECp4MMZh7XMc0jSxASxgxHivtqwC7SmitacyzVEhfZwptbpEJ0Y0ZNQMad0WXGxGJ9ADqeZGrQyAYCSmQok4Fj0TIuAwDyTVlJl6TTPpN6CzXNJEVurgluZgkLsrwMTFaSKwWkkoLTThfzXgtkTX-kG3YVV_JVQvehNZSbUm19WaJtUEhNY4hO_p91jFs2HeXFXktqM-nC3UC6_Jt_jybnrq_6gMeFcmq
linkProvider	IEEE
linkToHtml	http://cvtisr.summon.serialssolutions.com/2.0.0/link/0/eLvHCXMwlV3fS-QwEB7WVfB88Le4p97lwRfBuk3TNpnHRVwU11W8VXwraZrAgnaP3VXwv78k7a4eiuBbAxNaMs1kJjPzfQCHhlPkitIg52iCuCio3VJpHFg7iBI5au15yO57vN8XDw9404DjeS-M1toXn-kT9-hz-cVIPbursjYyB8fOF2AxieOIVt1ab8h66HmQHaZYwEIUs6RkiO3B7bUNBSN6Yh1kG2Wz_w4hz6rywRT786W79r0vW4fV2o8knUrxG9DQ5SasvEMX3ILbTkk6ubvK8L0LQXesNbnyjNHEuqrE996OR_loSgYVQNUjcdTLilxbO_JkR6dVHTv581paP3EynGzDXfdscHoe1BQKgYqQTgNhUpbHDqIlirlItQk1xURLYwxLRZFLFZpCo8sucimTlDM7YGkiE2FFFLIdaJajUu8CwVgqiQxNLkUsIy5URJUwjNuITXEVtqA9W9NM1fjijubiMfNxRoiZ1ULmtJDVWmjB0XzG3wpb4wvZLbfqc7l6wVuwP1NbVm--SeasUMSsa8h_fj7rNyyfD656We-if7kHP9x7qvq8fWhOx8_6AJbUy3Q4Gf_yf9g_xZPM8Q
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=An+Abstraction-Free+Method+for+Multirobot+Temporal+Logic+Optimal+Control+Synthesis&rft.jtitle=IEEE+transactions+on+robotics&rft.au=Luo%2C+Xusheng&rft.au=Kantaros%2C+Yiannis&rft.au=Zavlanos%2C+Michael+M&rft.date=2021-10-01&rft.pub=The+Institute+of+Electrical+and+Electronics+Engineers%2C+Inc.+%28IEEE%29&rft.issn=1552-3098&rft.eissn=1941-0468&rft.volume=37&rft.issue=5&rft.spage=1487&rft_id=info:doi/10.1109%2FTRO.2021.3061983&rft.externalDBID=NO_FULL_TEXT
thumbnail_l	http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/lc.gif&issn=1552-3098&client=summon
thumbnail_m	http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/mc.gif&issn=1552-3098&client=summon
thumbnail_s	http://covers-cdn.summon.serialssolutions.com/index.aspx?isbn=/sc.gif&issn=1552-3098&client=summon