A novel link index X proposed deals with the feature of molecule graph, the property of vertical atom and the bonding of atoms connected to each other. Matrices are used to represent these characters.

新的键指数X考虑了分子的图形特征，顶点原子的性质，顶点原子与相邻原子的键合情况，并以矩阵的形式把这些特征表达出来。

youdao

This is because the Google index assumes that a link is indicating that the page is useful and or important and thus makes it important inside the index.

FORBES: Google Should Ban Google Chrome from the Google Index

This module offers six headline stories from local news sites and a link through to the news index from the same site.

BBC: links to other news sites

Nofollow tells the Google spiders not to consider that link important and so does not bias the index by attributing importance to such paid links.

FORBES: Google Should Ban Google Chrome from the Google Index