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From "gekkokid">
Subject Re: What is stemming?
Date Sun, 20 Nov 2005 17:48:49 GMT
Hello fellow lucener :), firstly im no tutor but i will try my best to 
explain, if anyone believes im wrong please state it so our friend doesnt 
get the wrong idea,

here it goes. O_o
stemming is reducing the word to the root form, where lemmatisation is 
concerned with linguistics i believe

lemmatisation is "go", "gone", "going", "goes", "been" and "went"

where stemming a word would be reducing a word from "gone" to "go", so it 
can be matched to other stemmed words such as "going", as "going" stemmed 
would be "go" also,

a better example.
"engineering", "engineers", "engineered", "engineer"

these four words would not match up if they were tested for equality, 
however by stemming these words we can reduce them to a more basic form,

engineering --> engineer
engineers --> engineer
engineered --> engineer
engineer --> engineer

now we have stemmed words they will match for equality, so now if i try 
searching using the word for engineer, documents on engineering, engineers 
and engineered would be returned from a stemmed index/database.

I hope that helps. Do a search for "porter stemmer" for more information.


----- Original Message ----- 
From: "Koji Sekiguchi" <>
To: <>
Sent: Sunday, November 20, 2005 3:48 PM
Subject: What is stemming?

> Hello, Luceners!
> What is "stemming"?
> I have Lucene in Action and found the following definitions on page 103:
> - reducing words to a root form (stemming)
> - changing words into the basic form (lemmatization)
> but I cannot see the difference between them.
> I'm also confused by the following words on page 71:
> - convert terms to base word forms (stemming)
> It seems "lemmatization" to me...
> Could someone explain what "stemming" is?
> Some illustrative cases would be very appreciated.
> My mother tongue is not English.
> Thank you,
> Koji
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