Every circle graph of girth at least 5 is 3-colourable
نویسنده
چکیده
It is known that every triangle-free (equivalently, of girth at least 4) circle graph is 5-colourable (Kostochka, 1988) and that there exist examples of these graphs which are not 4-colourable (Ageev, 1996). In this note we show that every circle graph of girth at least 5 is 2-degenerate and, consequently, not only 3-colourable but even 3-choosable.
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ورودعنوان ژورنال:
- Discrete Mathematics
دوره 195 شماره
صفحات -
تاریخ انتشار 1999