{"oa":1,"intvolume":"       160","author":[{"last_name":"Kolmogorov","full_name":"Kolmogorov, Vladimir","first_name":"Vladimir","id":"3D50B0BA-F248-11E8-B48F-1D18A9856A87"}],"oa_version":"Preprint","issue":"4-5","abstract":[{"text":"Consider a convex relaxation f̂ of a pseudo-Boolean function f. We say that the relaxation is totally half-integral if f̂(x) is a polyhedral function with half-integral extreme points x, and this property is preserved after adding an arbitrary combination of constraints of the form x i=x j, x i=1-x j, and x i=γ where γ∈{0,1,1/2} is a constant. A well-known example is the roof duality relaxation for quadratic pseudo-Boolean functions f. We argue that total half-integrality is a natural requirement for generalizations of roof duality to arbitrary pseudo-Boolean functions. Our contributions are as follows. First, we provide a complete characterization of totally half-integral relaxations f̂ by establishing a one-to-one correspondence with bisubmodular functions. Second, we give a new characterization of bisubmodular functions. Finally, we show some relationships between general totally half-integral relaxations and relaxations based on the roof duality. On the conceptual level, our results show that bisubmodular functions provide a natural generalization of the roof duality approach to higher-order terms. This can be viewed as a non-submodular analogue of the fact that submodular functions generalize the s-t minimum cut problem with non-negative weights to higher-order terms.","lang":"eng"}],"date_published":"2012-03-01T00:00:00Z","date_updated":"2023-02-23T11:04:49Z","doi":"10.1016/j.dam.2011.10.026","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","department":[{"_id":"VlKo"}],"volume":160,"status":"public","_id":"3257","publication":"Discrete Applied Mathematics","external_id":{"arxiv":["1005.2305"]},"type":"journal_article","scopus_import":1,"day":"01","publication_status":"published","language":[{"iso":"eng"}],"month":"03","quality_controlled":"1","publisher":"Elsevier","publist_id":"3397","main_file_link":[{"open_access":"1","url":"http://arxiv.org/abs/1005.2305"}],"date_created":"2018-12-11T12:02:18Z","page":"416 - 426","title":"Generalized roof duality and bisubmodular functions","year":"2012","related_material":{"record":[{"status":"public","id":"2934","relation":"earlier_version"}]},"citation":{"ama":"Kolmogorov V. Generalized roof duality and bisubmodular functions. <i>Discrete Applied Mathematics</i>. 2012;160(4-5):416-426. doi:<a href=\"https://doi.org/10.1016/j.dam.2011.10.026\">10.1016/j.dam.2011.10.026</a>","short":"V. Kolmogorov, Discrete Applied Mathematics 160 (2012) 416–426.","mla":"Kolmogorov, Vladimir. “Generalized Roof Duality and Bisubmodular Functions.” <i>Discrete Applied Mathematics</i>, vol. 160, no. 4–5, Elsevier, 2012, pp. 416–26, doi:<a href=\"https://doi.org/10.1016/j.dam.2011.10.026\">10.1016/j.dam.2011.10.026</a>.","ieee":"V. Kolmogorov, “Generalized roof duality and bisubmodular functions,” <i>Discrete Applied Mathematics</i>, vol. 160, no. 4–5. Elsevier, pp. 416–426, 2012.","ista":"Kolmogorov V. 2012. Generalized roof duality and bisubmodular functions. Discrete Applied Mathematics. 160(4–5), 416–426.","chicago":"Kolmogorov, Vladimir. “Generalized Roof Duality and Bisubmodular Functions.” <i>Discrete Applied Mathematics</i>. Elsevier, 2012. <a href=\"https://doi.org/10.1016/j.dam.2011.10.026\">https://doi.org/10.1016/j.dam.2011.10.026</a>.","apa":"Kolmogorov, V. (2012). Generalized roof duality and bisubmodular functions. <i>Discrete Applied Mathematics</i>. Elsevier. <a href=\"https://doi.org/10.1016/j.dam.2011.10.026\">https://doi.org/10.1016/j.dam.2011.10.026</a>"}}