For any small positive real $\varepsilon$ and integer $t > \frac{1}{\varepsilon}$, we build a graph with a vertex deletion set of size $t$ to a tree, and twin-width greater than $2^{(1-\varepsilon) t}$. In particular, this shows that the twin-width is sometimes exponential in the treewidth, in the so-called oriented twin-width and grid number, and that adding an apex may multiply the twin-width by at least $2-\varepsilon$. Except for the one in oriented twin-width, these lower bounds are essentially tight.
翻译:对于任何小的正正实际$和整值$ >\frac{1\unvarepsilon}美元,我们用一个将顶部除去的一套大小为$t美元、双维大于$2 ⁇ (1-\varepsilon) t$的图来构建一个图表。特别是,这显示双边有时在树宽中指数化,在所谓的双边和网格数字中,增加一个顶点可能使双维增加至少2美元。除了一个面向双边的图外,这些下边基本上很紧。