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Friday, April 12, 2013 |
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Inductive tools for handling internally 4-connected binary matroids |
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A matroid is 3-connected if it does not break up as a 1-sum or a 2-sum. Numerous problems for matroids reduce eas- ily to the study of 3-connected matroids. Two powerful inductive tools for dealing with 3-connected matroids are Tutte's Wheels- and-Whirls Theorem and Seymour's Splitter Theorem. For sev- eral years, Carolyn Chun, Dillon Mayhew, and I have been seeking analogues of these theorems for internally 4-connected binary ma- troids, that is, binary matroids that do not break up as a 1-, 2-, or 3-sum. The class of such matroids includes the cycle matroids of internally 4-connected graphs, those 3-connected simple graphs that are 4-connected except for the possible presence of degree-3 vertices. This talk will report on our progress towards nding these analogues. |