Snowball Stemming：定义空区域

Question

我正在尝试了解滚雪球词干提取算法。有类似的问题与例子，但不是我的。该算法使用两个区域 R1 和 R2，定义如下：

R1 is the region after the first non-vowel following a vowel, or is the null region at the end of the word if there is no such non-vowel.

R2 is the region after the first non-vowel following a vowel in R1, or is the null region at the end of the word if there is no such non-vowel.

http://snowball.tartarus.org/texts/r1r2.html

我不明白，"the null region at the end of the word"是什么。有人可以给我一些例子吗？

Answer 1

Null region表示空区域，没有字母。您错过了 documentation page:

中的示例

Below, R1 and R2 are shown for a number of English words,
b   e   a   u   t   i   f   u   l
                  |<------------->|    R1
                          |<----->|    R2
Letter t is the first non-vowel following a vowel in beautiful, so R1 is iful. In iful, the letter f is the first non-vowel following a vowel, so R2 is ul.
b   e   a   u   t   y
                  |<->|    R1
                    ->|<-  R2 
In beauty, the last letter y is classed as a vowel. Again, letter t is the first non-vowel following a vowel, so R1 is just the last letter, y. R1 contains no non-vowel, so R2 is the null region at the end of the word.
b   e   a   u
            ->|<-  R1
            ->|<-  R2

Snowball Stemming：定义空区域

Snowball Stemming: defining Null Region

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