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Wegner
Colouring the square of a planar graph ★★
Author(s): Wegner
Conjecture Let
be a planar graph of maximum degree
. The chromatic number of its square is
![$ G $](/files/tex/b8e7ad0330f925492bf468b5c379baec88cf1b3d.png)
![$ \Delta $](/files/tex/e3f8e135c571143e94f1d4f236326b862080b200.png)
- \item at most
![$ 7 $](/files/tex/daebc9d78b81a4cd1f0e6bae70785e92cf2ce1ea.png)
![$ \Delta =3 $](/files/tex/aced9ebeab44df5a1f3efd1bfb967dd0fe0883c4.png)
![$ \Delta+5 $](/files/tex/a7be33e67abdf15a956bdc393747bb7f75bbd905.png)
![$ 4\leq\Delta\leq 7 $](/files/tex/edab53b759e15d01350d22f54590e6ee9a99bca9.png)
![$ \left\lfloor\frac32\,\Delta\right\rfloor+1 $](/files/tex/d5aa6f60013e17601f35a898a36936e347bc9a8b.png)
![$ \Delta\ge8 $](/files/tex/0782472fc66f76ac853e14ef0f2ded9aaac96451.png)
Keywords:
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