边界色多项式
Boundary chromatic polynomial
摘要:
我们考虑嵌入环中的平面图的适当染色,使得一个边缘上的顶点可以取Q_s颜色,而所有其余的顶点可以取Q颜色。相应的色多项式与边界环模型的配分函数有关。利用后者的结果,在二维或准一维无限图的极限下,导出了着色问题(具有实Q和Q_s)的相图。特别地,我们发现Beraha数Q= 4cos^2(pi/n)对通常的色多项式所起的特殊作用并不延伸到Q不同于Q_s的情况。与(稀缺)现有的数值结果的协议是完美的,进一步的数值检查。
英文摘要:
We consider proper colorings of planar graphs embedded in the annulus, such that vertices on one rim can take Q_s colors, while all remaining vertices can take Q colors. The corresponding chromatic polynomial is related to the partition function of a boundary loop model. Using results for the latter, the phase diagram of the coloring problem (with real Q and Q_s) is inferred, in the limits of two-dimensional or quasi one-dimensional infinite graphs. We find in particular that the special role played by Beraha numbers Q=4 cos^2(pi/n) for the usual chromatic polynomial does not extend to the case Q different from Q_s. The agreement with (scarce) existing numerical results is perfect; further numerical checks are presented here.
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