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$B0J2, $\vert E\vert$, $\vert V\vert$ $BEy$N5-9f$N0UL#$K$D$$$F$O652J=q;2>H$N$3$H!#(B

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$BJ?LL%0%i%U$,C1=c%0%i%U$G$"$k$H$-!"(B$R\geq 2$ $B$J$i$P(B

$$3R\leq 2\vert E\vert$$

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$$\mbox{$B3FNN0h$r0O$`JU$N?t$N9g7W(B} = \mbox{($BJU$N?t(B)}\times 2 \geq 3\times\mbox{($BNN0h$N?t(B)}$$

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$B;03Q7A$,4^$^$l$J$$C1=cJ?LL%0%i%U$G$O!"(B$R\geq 2$ $B$KBP$7$F(B

$$4R\leq 2\vert E\vert$$

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$K_{3,3}$ $B$O(B $\vert E\vert=9$, $\vert V\vert=6$, $k=1$ $B$J$N$G!"$b$7J?LL%0%i%U$N7A$K(B $B=q$1$?$H$9$k$H!"%*%$%i!<$N8x<0$K$h$j(B

$$R=k+1-\vert V\vert+\vert E\vert=1+1-6+9=5$$

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$$4R\leq 2\vert E\vert$$

$B$G$J$i$J$1$l$P$J$i$:!"$=$l$O(B $4R=20$, $2\vert E\vert=18$ $B$KL7=b$9$k!#(B

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