[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-140009-105":59,"doc-detail-140009-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","solving-hard-subgraph-problems-in-parallel","Solving Hard Subgraph Problems in Parallel","","This PhD thesis advances exact, practical algorithms for finding subgraphs, focusing on maximum clique, subgraph isomorphism, and maximum common subgraph problems. It addresses both pure formulations and variants with labels and domain-specific constraints, spanning use in computing and disciplines such as biochemistry, electrical engineering, mathematics, and sociology. It studies how constraint-based search can handle very large real-world graphs and investigates how to generate truly hard instances, connecting performance to branching heuristics and parallelism.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":40,"@type":76,"position":81},"https://docshare.wps.com/document/research-report/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/solving-hard-subgraph-problems-in-parallel/140009/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/solving-hard-subgraph-problems-in-parallel/140009.png","ImageObject",300,407,{"name":92,"@type":93},"Ethan Miller","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-09-20","2026-08-24",true,{"@type":102,"interactionType":103,"userInteractionCount":24},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"Which subgraph problems does the thesis focus on?","Question",{"text":112,"@type":113},"It concentrates on maximum clique, subgraph isomorphism, and maximum common subgraph problems, studying both pure versions and constrained variants with labels and domain-specific requirements.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How does the thesis connect hardness to search performance?",{"text":117,"@type":113},"It explores constraint-based search and investigates whether “really hard” instances can be generated, using combinatorial phase transition ideas to better understand branching heuristics.",{"name":119,"@type":110,"acceptedAnswer":120},"What parallelism approaches are investigated?",{"text":121,"@type":113},"The thesis exploits two kinds of parallelism: bit parallelism for operations over vertex sets, and thread parallelism over multiple CPU cores, evaluating performance characteristics like lack of risk, scalability, and reproducibility.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},140009,1787566140,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":39,"category_name":40,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":24,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":129,"read_time":144},687207017582,"https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d","McCreesh, Ciaran (2017) Solving hard subgraph problems in parallel. PhD thesis.  \n[http://theses.gla.ac.uk/8322/](http://theses.gla.ac.uk/8322/)  \nCopyright and moral rights for this work are retained by the author  \nA copy can be downloaded for personal non-commercial research or study, without prior permission or charge  \nThis work cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author  \nThe content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author  \nWhen referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given  \nEnlighten:Theses  \n[http://theses.gla.ac.uk/](http://theses.gla.ac.uk/)  \n[theses@gla.ac.uk](theses@gla.ac.uk)  \nSOLVING HARD SUBGRAPH PROBLEMS  \nIN PARALLEL  \nCIARAN MCCREESH  \nSUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF  \nDoctor of Philosophy  \nSCHOOL OF COMPUTING SCIENCE  \nCOLLEGE OF SCIENCE AND ENGINEERING UNIVERSITY OF GLASGOW  \n16 TH JULY 2017  \nAbstract  \nThis thesis improves the state ofthe art in exact, practical algorithms for finding subgraphs. We study maximum clique, subgraph isomorphism, and maximum common subgraph problems. These are widely applicable: within computing science, subgraph problems arise in document clustering, computer vision, the design of communication protocols, model checking, compiler code generation, malware detection, cryptography, and robotics; beyond, applications occur in biochemistry, electrical engineering, mathematics, law enforcement, fraud detection, fault diagnosis, manufacturing, and sociology. We therefore consider both the “pure” forms of these problems, and variants with labels and other domain-specific constraints.  \nAlthough subgraph-finding should theoretically be hard, the constraint-based search algorithms we discuss can easily solve real-world instances involving graphs with thousands of vertices, and millions of edges. We therefore ask: is it possible to generate “really hard”instances for these problems, and if so, what can we learn? By extending research into combinatorial phase transition phenomena, we develop a better understanding of branching heuristics, as well as highlighting a serious flaw in the design of graph database systems.  \nThis thesis also demonstrates how to exploit two of the kinds of parallelism offered by current computer hardware. Bit parallelism allows us to carry out operations on whole sets of vertices in a single instruction—this is largely routine. Thread parallelism, to make use of the multiple cores offered by all modern processors, is more complex. We suggest three desirable performance characteristics that we would like when introducing thread parallelism: lack of risk (parallel cannot be exponentially slower than sequential), scalability (adding more processing cores cannot make runtimes worse), and reproducibility (the same instance on the same hardware will take roughly the same time every time it is run) . We then detail thedifficulties in guaranteeing these characteristics when using modern algorithmic techniques.  \nBesides ensuring that parallelism cannot make things worse, we also increase the likelihood of it making things better. We compare randomised work stealing to new tailored strategies, and perform experiments to identify the factors contributing to good speedups. We show that whilst load balancing is difficult, the primary factor influencing the results is the interaction between branching heuristics and parallelism. By using parallelism to explicitly offset the commitment made to weak early branching choices, we obtain parallel subgraph solvers which are substantially and consistently better than the best sequential algorithms.  \nAcknowledgements  \nI would like to thank Patrick Prosser for letting me do this: I hope you have enjoyed it as much as I have. Thanks also to my second supervisor, David Ma","cbCaikwa0Q49N4jb","https://ap.wps.com/l/cbCaikwa0Q49N4jb","pdf",12200065,264,"English","# Introduction\n## Hard Subgraph Problems\n### Maximum Clique\n### Subgraph Isomorphism\n### Maximum Common Subgraph","[{\"question\":\"Which subgraph problems does the thesis focus on?\",\"answer\":\"It concentrates on maximum clique, subgraph isomorphism, and maximum common subgraph problems, studying both pure versions and constrained variants with labels and domain-specific requirements.\"},{\"question\":\"How does the thesis connect hardness to search performance?\",\"answer\":\"It explores constraint-based search and investigates whether “really hard” instances can be generated, using combinatorial phase transition ideas to better understand branching heuristics.\"},{\"question\":\"What parallelism approaches are investigated?\",\"answer\":\"The thesis exploits two kinds of parallelism: bit parallelism for operations over vertex sets, and thread parallelism over multiple CPU cores, evaluating performance characteristics like lack of risk, scalability, and reproducibility.\"}]","Solving Hard Subgraph Problems in Parallel | PDF",665]