Pfaffian graphs, T -joins and crossing numbers
نویسنده
چکیده
We characterize Pfaffian graphs in terms of their drawings in the plane. We generalize the techniques used in the proof of this characterization, and prove a theorem about the numbers of crossings in T -joins in different drawings of a fixed graph. As a corollary we give a new proof of a theorem of Kleitman on the parity of crossings in drawings of K2j+1 and K2j+1,2k+1.
منابع مشابه
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عنوان ژورنال:
- Combinatorica
دوره 28 شماره
صفحات -
تاریخ انتشار 2008