This document discusses natural language processing (NLP) and its application in spam detection through methods such as n-gram modeling, word stemming, and Bayesian classification. It outlines a proposed model that includes a threshold counter to enhance spam filtering efficiency while managing web server congestion. The model involves multiple processing steps, including URL checks and keyword extraction, to classify incoming emails as spam or legitimate.

2.  INTRODUCTION
 NATURAL LANGUAGE PROCESSING
 SPAMMING
 RELATED WORK
 N-GRAM MODELLING
 WORD STEMMING
 BAYESIAN CLASSIFICATION

3.  PROPOSED MODEL
 COMPONENTS
 BLOCK DIAGRAM
 WORKING
 CONCLUSION
 QUESTION & ANSWER
 THANK YOU

4. Natural Language Processing (NLP)
is a field of computer science and
linguistics concerned with the
interactions between computers and
human (natural) languages.

5. Spamming is the use of electronic
messaging systems like e-mails and
other digital delivery systems and
broadcast media to send unwanted
bulk messages indiscriminately.

6. N-GRAM MODELLING
WORD STEMMING
BAYESIAN CLASSIFICATION

7.  An N-gram is an N-character slice of a longer string.
 N-grams of several different lengths simultaneously are
used in the processing while detecting spam emails.
 In N-gram blank space is replaces by underscore
character(“_”).

8. Here the example ,
WORD = STAY
 Bi-grams: _S, ST, TA, SY, Y_
 Tri-grams: _ _S, _ST, STA, TAY, AY_, Y_
 Quad-grams: _ _ _ S, _ _ ST, _STA, STAY,
TAY_, AY_ _, Y_ _ _

9. The following steps are used in a word stemming algorithm:
 Remove all non-alpha characters. (Allow some characters
like '/' ' ' '|' etc. which can be used together to look like some
characters, such as / for 'V')
 Remove all vowels from the word except the initial one.
 Replace all digits and symbols by similar looking digits or
characters.

10.  Replace consecutive repeated characters by a
single character and vice versa.
 Use phonetic algorithms like sound ex on the
resultant string.
 Give it a numeric value depending on the
operations performed over it.
 Update the database for that particular keyword.

11.  Bayesian Spam Filtering is a statistical method of
classifying an email into spam and legitimate classes.
 Naive Bayes classifiers work by correlating the use of
tokens with spam and non-spam emails and then using
Bayesian inference to calculate a probability that an email is
or is not spam.

12. Here,
A= no. Of Ham meassage
b= no. Of Spam messgae

13.  Email Input
 URL Source Check
 URL Blacklist Database
 Threshold Counter
 Keyword Extractor
 Classifier
 NLP Engine

15. WORKING
 An unclassified email is taken as input for processing.
 The URL Source checking block checks the URL of the incoming
email and searches URL Blacklist Database to find a match. If the
search is successful then, it categorizes the email as a spam or
considers it to be ham and processes further.
 At the same time there is a Threshold Counter which keeps track
of the number of emails coming from this source over a period of
time t.

16.  The Email is then passed to the Keyword Extractor which
will tokenize the message into keywords.
 These keywords are passed to the Classifier which will
classify the mail into a specific category E.
 The email is then passed to the NLP Engine along with its
category.

17. Spam mails are a serious concern to and a major annoyance
for many Internet users. The mode proposed as a solution in
this paper is highly beneficial because it introduces a
threshold counter which helps overcome congestion on the
web server and also maintain the spam filter efficiency but
at the same time, it also requires overhead storage space for
the databases.