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Talk:Dulmage–Mendelsohn decomposition

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84: 74: 53: 22: 171:-- This definition may give the impression that every bipartite graph has a perfect matching, which is not true. Does this mean that the Dulmage–Mendelsohn decomposition is defined only on such graphs that have a perfect matching? If so, then this should be stated clearly in order to prevent confusion. -- 209:
I realized, to my horror, that Bunus and Fritzson (see additional link 1 in the article) were terribly wrong in their 2002 paper, as they were in the one before that ("A Debugging Scheme for Declarative Equation-Based Modeling Languages"). In both of these articles, they use the algorithm with sets
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The DM decomposition indeed applies to any bipartite graph; even better, in practice, the coarse decomposition is only useful when no perfect matching exists (including, but not limited to, non-square cases). It is stated that one input of the algorithm is D, 'the set of vertices in G that are not
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E, U and O that has been, since, published by Irving et al. ("Rank-Maximal Matchings", 2006), and talk about this algorithm as "the Dulmage-Mendelsohn decomposition algorithm". It is not. Not only the article by Irving does not mention Dulmage nor Mendelsohn at any point, but
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matched in at least one maximum matching of G'. If perfect matchings exist, then D is an empty set and the coarse DM decomposition is trivial; then any finer decomposition roughly consists in finding Strongly Connected Components, i.e., calling Tarjan to the rescue.
217:(For those who would like to check: the DM decomposition of this example is {e4,eq5,eq6,eq7} as the underdetermined part, {eq1,eq2,eq3} as the overdetermined part, no square/enabled part in between. I also checked these results with Matlab 2018a.) 163:"the Dulmage–Mendelsohn decomposition is a partition of the vertices of a bipartite graph into subsets, with the property that two adjacent vertices belong to the same subset if and only if they are paired with each other 140: 220:
To my knowledge, the works by Bunus and Fritzson are the only reason why this 'alternative DM decomposition' is mentioned in the Knowledge article, and it is actually wrong. As such,
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I am currently working, as a post-doctoral student, on the modeling and simulation of physical systems, and as such, I had to come back to the gool old DM decomposition.
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Of course, I highly encourage you to check the veracity of what I just wrote before taking any decision, and as a non-registered user, I will not edit the page myself.
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the results yielded by this algorithm differ from the canonical DM decomposition, even on the very exemple provided by Bunus and Fritzson in their 2002 paper
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on Knowledge. If you would like to participate, please visit the project page, where you can join
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this whole section should be removed from the article
101:, a collaborative effort to improve the coverage of 8: 19: 47: 49: 7: 95:This article is within the scope of 202:Factual error: alternate definition 38:It is of interest to the following 165:in a perfect matching of the graph 14: 259:Low-priority mathematics articles 115:Knowledge:WikiProject Mathematics 254:Start-Class mathematics articles 118:Template:WikiProject Mathematics 82: 72: 51: 20: 135:This article has been rated as 1: 181:16:42, 28 December 2013 (UTC) 109:and see a list of open tasks. 275: 240:08:31, 19 March 2020 (UTC) 197:08:36, 19 March 2020 (UTC) 134: 67: 46: 158:Applicable to any graph? 141:project's priority scale 98:WikiProject Mathematics 28:This article is rated 230:Thanks for reading. 121:mathematics articles 90:Mathematics portal 34:content assessment 155: 154: 151: 150: 147: 146: 266: 123: 122: 119: 116: 113: 92: 87: 86: 76: 69: 68: 63: 55: 48: 31: 25: 24: 16: 274: 273: 269: 268: 267: 265: 264: 263: 244: 243: 204: 160: 120: 117: 114: 111: 110: 88: 81: 61: 32:on Knowledge's 29: 12: 11: 5: 272: 270: 262: 261: 256: 246: 245: 232:92.167.218.166 203: 200: 189:92.167.218.166 185: 169: 168: 159: 156: 153: 152: 149: 148: 145: 144: 133: 127: 126: 124: 107:the discussion 94: 93: 77: 65: 64: 56: 44: 43: 37: 26: 13: 10: 9: 6: 4: 3: 2: 271: 260: 257: 255: 252: 251: 249: 242: 241: 237: 233: 228: 225: 223: 218: 215: 213: 207: 201: 199: 198: 194: 190: 183: 182: 178: 174: 166: 162: 161: 157: 142: 138: 132: 129: 128: 125: 108: 104: 100: 99: 91: 85: 80: 78: 75: 71: 70: 66: 60: 57: 54: 50: 45: 41: 35: 27: 23: 18: 17: 229: 226: 221: 219: 216: 211: 208: 205: 184: 170: 164: 137:Low-priority 136: 96: 62:Low‑priority 40:WikiProjects 112:Mathematics 103:mathematics 59:Mathematics 30:Start-class 248:Categories 173:Erel Segal 139:on the 36:scale. 236:talk 193:talk 177:talk 131:Low 250:: 238:) 224:. 214:. 195:) 179:) 234:( 191:( 175:( 167:" 143:. 42::

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