{"id":28,"date":"2024-06-05T16:43:35","date_gmt":"2024-06-05T16:43:35","guid":{"rendered":"https:\/\/taskforce.bi-level.org\/?page_id=28"},"modified":"2024-06-05T18:15:27","modified_gmt":"2024-06-05T18:15:27","slug":"home","status":"publish","type":"page","link":"https:\/\/taskforce.bi-level.org\/","title":{"rendered":"Bilevel Optimization"},"content":{"rendered":"<div class=\"wp-block-image\">\n<figure class=\"alignright is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"417\" height=\"417\" src=\"https:\/\/taskforce.bi-level.org\/wp-content\/uploads\/2024\/06\/image-edited.png\" alt=\"\" class=\"wp-image-43\" style=\"width:292px;height:auto\" srcset=\"https:\/\/taskforce.bi-level.org\/wp-content\/uploads\/2024\/06\/image-edited.png 417w, https:\/\/taskforce.bi-level.org\/wp-content\/uploads\/2024\/06\/image-edited-300x300.png 300w, https:\/\/taskforce.bi-level.org\/wp-content\/uploads\/2024\/06\/image-edited-150x150.png 150w\" sizes=\"auto, (max-width: 417px) 85vw, 417px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\"><strong>Bilevel Optimization<\/strong> is a challenging class of problems where the performance of an upper level \u201cleader\u201d problem is realizable only if the decision vector of a nested lower level \u201cfollower\u201d problem is at its optimum.  Alternatively, it can also be defined as an optimization problem which has another optimization problem as a constraint. Several real-life problems are hierarchical in nature and suited for modelling as bilevel optimization problem. These include (but are not limited to) transportation, policymaking, supply-chain management, economics, engineering design, defense strategies, cyber-security, etc. This hierarchical nature of the problem induces several unique challenges, such as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Exorbitant numbers<\/strong> of function evaluations are required for solving the problem, since evaluation of each upper level solution requires optimization of a lower level problem. It is proven that even if both levels of the problem are linear, the resulting problem is NP-hard.<\/li>\n\n\n\n<li><strong>The leader and follower problems may be uncooperative<\/strong>, posing a severe difficulty for the ranking techniques used in evolutionary methods<\/li>\n\n\n\n<li>Further <strong>complexity is induced<\/strong> when the upper\/lower level problems contain <strong>multiple objectives<\/strong> and\/or constraints.<\/li>\n\n\n\n<li><strong>Performance<\/strong> characterization and <strong>benchmarking of algorithms<\/strong> for such problems is not straightforward, since a suboptimal solution at lower level may result in a better-than-optimal solution at upper level.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Purpose of the TF<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A number of studies exist in the classical literature to solve bilevel problems, but they usually involve assumptions on or knowledge of mathematical properties of the involved functions, which may severely limit their application for problems that are highly nonlinear or black-box. Evolutionary\/metaheuristic and hybrid methods offer a way forward to solve such problems. The interest in use of evolutionary techniques is relatively recent, but is gaining significant traction. This task force aims to intensify efforts towards development of powerful techniques to solve difficult bilevel problems currently intractable. Some of the channels include<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Building an online community for sharing latest developments and resources to advance the field<\/li>\n\n\n\n<li>Organization of special sessions and tutorials in major events and conferences such as CEC, EMO, PPSN, SSCI, etc.<\/li>\n\n\n\n<li>Organization of edited books and special issues in journals<\/li>\n\n\n\n<li>Collaborative projects and papers towards solving open challenges in the field<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Technical Committee<\/h2>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h2 class=\"wp-block-heading\">Chair<\/h2>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"116\" height=\"116\" src=\"https:\/\/taskforce.bi-level.org\/wp-content\/uploads\/2024\/06\/image-3-edited.png\" alt=\"\" class=\"wp-image-62\" style=\"width:126px;height:auto\"\/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Jes\u00fas-Adolfo Mej\u00eda-de-Dios<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h2 class=\"wp-block-heading\">Vice-Chair<\/h2>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"128\" height=\"128\" src=\"https:\/\/taskforce.bi-level.org\/wp-content\/uploads\/2024\/06\/image-2.png\" alt=\"\" class=\"wp-image-58\"\/><\/figure>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">Jos\u00e9-Fernando Camacho-Vallejo<\/p>\n<\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Members<\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table><thead><tr><th>Name<\/th><th>Institution<\/th><th>Country<\/th><\/tr><\/thead><tbody><tr><td><a rel=\"noreferrer noopener\" href=\"http:\/\/faculty.iima.ac.in\/~asinha\/\" target=\"_blank\">Ankur Sinha<\/a><\/td><td>Indian Institute of Management Ahmedabad (IIMA)<\/td><td>India<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"http:\/\/mdolab.net\/Hemant\/\" target=\"_blank\">Hemant Singh<\/a><\/td><td>University of New South Wales (UNSW)<\/td><td>Australia<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"http:\/\/www.lncc.br\/~hcbm\/\" target=\"_blank\">Helio J.C. Barbosa<\/a><\/td><td>Laborat\u00f3rio Nacional de Computa\u00e7\u00e3o Cient\u00edfica (LNCC)<\/td><td>Brazil<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.researchgate.net\/profile\/Jaqueline_S_Angelo\" target=\"_blank\">Jaqueline S. Angelo<\/a><\/td><td>Laborat\u00f3rio Nacional de Computa\u00e7\u00e3o Cient\u00edfica (LNCC)<\/td><td>Brazil<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/college.lclark.edu\/live\/profiles\/46-moriah-b-bostian\" target=\"_blank\">Moriah B. Bostian<\/a><\/td><td>Lewis and Clarke College<\/td><td>USA<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"http:\/\/www.fcfm.uanl.mx\/en\/node\/1541\" target=\"_blank\">Fernando Camacho<\/a><\/td><td>Universidad Aut\u00f3noma de Nuevo Le\u00f3n (UANL)<\/td><td>Mexico<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/sites.google.com\/site\/abirchaabani\/home\" target=\"_blank\">Abir Chaabani<\/a><\/td><td>Institut Sup\u00e9rieur de Gestion de Tunis (ISG) Tunis<\/td><td>Tunisia<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.egr.msu.edu\/people\/profile\/kdeb\" target=\"_blank\">Kalyanmoy Deb<\/a><\/td><td>Michigan State University (MSU)<\/td><td>USA<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.researchgate.net\/profile\/Eduardo_Krempser\" target=\"_blank\">Eduardo Krempser<\/a><\/td><td>Oswaldo Cruz Foundation<\/td><td>Brazil<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.researchgate.net\/profile\/Hecheng_Li2\" target=\"_blank\">Hecheng Li<\/a><\/td><td>Qinghai Normal University<\/td><td>China<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.rmit.edu.au\/contact\/staff-contacts\/academic-staff\/l\/li-professor-xiaodong\" target=\"_blank\">Xiaodong Li<\/a><\/td><td>RMIT University Melbourne<\/td><td>Australia<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/people.aalto.fi\/pekka.malo\" target=\"_blank\">Pekka Malo<\/a><\/td><td>AALTO University<\/td><td>Finland<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.uts.edu.au\/staff\/jie.lu\" target=\"_blank\">Jie Lu<\/a><\/td><td>University of Technology Sydney (UTS)<\/td><td>Australia<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/www.uts.edu.au\/staff\/guangquan.zhang\" target=\"_blank\">Guangquan Zhang<\/a><\/td><td>University of Technology Sydney (UTS)<\/td><td>Australia<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/ieeexplore.ieee.org\/author\/37293653000\" target=\"_blank\">Yuping Wang<\/a><\/td><td>Xidian University<\/td><td>China<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"https:\/\/scholar.google.com\/citations?user=aFCzWxcAAAAJ&amp;hl=en\" target=\"_blank\">Gerald Whittaker<\/a><\/td><td>Oregon State University (ORST)<\/td><td>USA<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"http:\/\/mdolab.net\/Ray\/\" target=\"_blank\">Tapabrata Ray<\/a><\/td><td>University of New South Wales (UNSW)<\/td><td>Australia<\/td><\/tr><tr><td><a rel=\"noreferrer noopener\" href=\"http:\/\/www.lifl.fr\/~talbi\/\" target=\"_blank\">El-Ghazali Talbi<\/a><\/td><td>University of Lille<\/td><td>France<\/td><\/tr><tr><td><a href=\"http:\/\/jmejia.bi-level.org\" data-type=\"link\" data-id=\"jmejia.bi-level.org\">Jes\u00fas-Adolfo Mej\u00eda-de-Dios<\/a><\/td><td>Universidad Aut\u00f3noma de Coahuila<\/td><td>Mexico<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Please feel free to suggest\/recommend other researchers working in the area to join.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>Bilevel Optimization is a challenging class of problems where the performance of an upper level \u201cleader\u201d problem is realizable only if the decision vector of a nested lower level \u201cfollower\u201d problem is at its optimum. Alternatively, it can also be defined as an optimization problem which has another optimization problem as a constraint. Several real-life &hellip; <a href=\"https:\/\/taskforce.bi-level.org\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Bilevel Optimization&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-28","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=\/wp\/v2\/pages\/28","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=28"}],"version-history":[{"count":6,"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=\/wp\/v2\/pages\/28\/revisions"}],"predecessor-version":[{"id":68,"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=\/wp\/v2\/pages\/28\/revisions\/68"}],"wp:attachment":[{"href":"https:\/\/taskforce.bi-level.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}