V3, v4 and redirect to the new folder. Constantly changing the main root location may cause you to lose backlink counts and ranking.

经常改变根目录的位置会导致你丢失反向链接的数量并影响rank值。

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As the search engine ranking rules and algorithms are constantly changing, and these rules and algorithms also is a commercial secret, it is impossible to guarantee in a row of several effects.

由于搜索引擎的排名规则及算法是是在不断改变中的，而且这些规则和算法又是商业机密，所以不可能达到保证排在某几位的效果的。

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In 70% of three-candidate elections, changing the procedure changes the final ranking.

ECONOMIST: The mathematics of voting