際際滷

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1
2
mmm
cbaw 2
We pick
Let be the integer in the Pumping Lemma
Pick a string such that:
w Lw 
mw ||length
m
}0,:{ 鰹 
lncbaL lnln
and
3
Write
zyxcba mmm
2
it must be that length
From the Pumping Lemma
cccbcabaaaaaxyz ..................
x y z
m m m2
1||,|| 鰹 ymyx
1, 鰹 kay kThus:
4
From the Pumping Lemma:
Lzyx i

...,2,1,0i
Thus:
mmm
cbazyx 2

Lxzzyx =0
1, 鰹 kay k
5
From the Pumping Lemma:
Lcccbcabaaaxz  ...............
x z
km  m m2
mmm
cbazyx 2
 1, 鰹 kay k
Lxz 
Thus:
Lcba mmkm
 2
6
Lcba mmkm
 2
Lcba mmkm
 2
BUT:
CONTRADICTION!!!
}0,:{ 鰹 
lncbaL lnln
1k
7
Our assumption that
is a regular language is not true L
Conclusion: L is not a regular language
Therefore:
8
Regular languages
Non-regular languages
}0:{ !
鰹 naL n

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