The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
1. The International Journal Of Engineering And Science (IJES)
|| Volume || 4 || Issue || 4 || Pages || PP.49-54|| 2015 ||
ISSN (e): 2319 – 1813 ISSN (p): 2319 – 1805
www.theijes.com The IJES Page 49
On the Construction of Cantor like Sets
Dr. S. M. Padhye1
, Satish B. Khobragade2
Associate Professor, HOD, Department Of Mathematics, Shri R.L.T. College Of Science, Akola, Maharashtra,
India1
Research Student, Department Of Mathematics, Shri R.L.T. College Of Science, Akola, Maharashtra, India2
-----------------------------------------------------------ABSTRACT----------------------------------------------------------
In this paper we construct a Cantor like set S from any sequence { } with 0< <1 with the help of
sequence { } of subsets of [0,1] such that ,m( ) = and S = ∩ with m(S) =
.Further ∑ = ∞ if and only if m(S) = 0. Cantor ternary set comes out to be a particular case of
construction of Cantor like sets by choosing = for all n. Similarly we can construct Cantor - set by
choosing = for all n. In the construction of Cantor - set the length of remaining closed intervals at each
stage are equal to , k = 1,2,3,…………… Also we can construct Cantor - set by choosing = for all n.
Here in the construction of Cantor - set the length of remaining closed intervals at each stage are equal to
, k = 1,2,3,……………
KEY WORDS: - Cantor set, Cantor like sets.
---------------------------------------------------------------------------------------------------------------------------------------
Date of Submission: 04-April-2015 Date of Accepted: 25-April-2015
---------------------------------------------------------------------------------------------------------------------------------------
Lemma 1:- Given any sequence { } with 0< <1,∑ = ∞ if and only if )= 0
Proof :- First step: Let = ∞
Then we have to show that )= 0 i.e. )= 0
Here we use 1- ≤ , 0 ≤ < 1
1- ≤ i =1,2,3,…………..
1- ≤
1- ≤
1- ≤
Multiplying all these inequalities we get,
(1- )(1- )…………….(1- ) ≤ . ۰۰۰۰۰۰
) ≤ ………………………(1)
2. On the Construction of Cantor like Sets
www.theijes.com The IJES Page 50
To show that )= 0, let > 0 be given. Put M = .
Since ∑ =∞ then there is N such that for n ≥ N ═> > M
>
>
>
< ………………………(2)
From equation (1) and (2) we get ,
) < for all n ≥ N.
Thus )= 0
)= 0
Conversely:-Let < ∞ i.e. ∑ < ∞ is convergent.
We show that ) ≠ 0 .
Let Pn = )
Since ≥ 0, ≠ 1 j and ∑ < ∞ .
we choose N so large that + + ۰۰۰۰۰۰< --------------------- (3)
Then using induction we prove that for all n ≥ N, (1 - )(1- )۰۰۰۰۰(1- ) ≥ [1- ( + +
۰۰۰۰۰ + )]
For n = N, the inequality is obvious. For n > N
If (1 - )(1- )۰۰۰۰۰(1- ) ≥ [1- ( + +۰۰۰۰ + )] then
(1 - )(1- )۰۰۰۰۰(1- ) (1 - ) ≥ [1- ( + +۰۰۰۰ + )] (1 - )
= [1- ( + + ۰۰۰۰ + )] + ( + + ۰۰۰۰ )
≥ [1- ( + +۰۰۰۰ + )]
Thus (1 - )(1- )۰۰۰۰۰(1- ) (1 - ) ≥ [1- ( + +۰۰۰۰ + )]
By induction the inequality holds for n ≥ N
i.e. (1 - )(1- )۰۰۰۰۰(1- ) ≥ [1- ( + + ۰۰۰۰۰ + )] for all n ≥ N ………….(4)
Now by using equation (3) we get,
(1 - )(1- )۰۰۰۰۰(1- ) ≥ [1- ] =
(1 - )(1- )۰۰۰۰۰(1- ) > ,n ≥ N ………………………. (5)
Now for n ≥ N, =
=
= > ,n ≥ N ( From equation (5))
3. On the Construction of Cantor like Sets
www.theijes.com The IJES Page 51
> ,n ≥ N ………………………. (6)
{ } ≥ ≠ 0 ………………………. (7)
Consider
- = -
- = [ 1- (1- ) ]
- = ≥ 0
- ≥ 0
{ } is monotonic decreasing and bounded below by .
{ } = ≥
Pn ≥ PN-1
Pn =α PN-1 , where α≥ 1/2
) =α {PN-1} , where α≥ 1/2
═> ) is a positive number
) ≠ 0
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Lemma 2 :-
If 0 < < 1, n ≥ 1, = + +۰۰۰۰۰۰+ and = (1- )(1- )…………….(1- ) then (1- ) ≤
≤
Proof :- Given
0 < < 1, n ≥ 1, = + +۰۰۰۰۰۰+ and
= (1- )(1- )…………….(1- )
≥ 1 – ( + +۰۰۰۰۰۰+ ) ( From equation (4) of Lemma 1)
≥ 1 -
1 – ≤ …………………………………..(1)
Now,
(1- )(1 + ) = 1 – < 1
(1- )(1 + ) < 1
(1- )<
4. On the Construction of Cantor like Sets
www.theijes.com The IJES Page 52
Similarly, (1- ) <
(1- ) <
Multiplying all these equations we get,
(1- )(1- )…………….(1- ) ≤ …………………………(2)
Now
) = 1+( + +۰۰۰+ )+( + +۰۰۰)+( +۰۰۰۰ ( +۰۰۰۰۰
) ≥ 1+ + +۰۰۰+
═> ≤
Putting in equation (2) we get,
(1- )(1- )…………….(1- ) ≤
≤
≤ ………………………………(3)
From equation (1) and (3) we get,
(1- ) ≤ ≤
* * * * * * * * * * * * * * * * * * * * * * * * * * *
Corollary 3 :-
If in addition lim = and lim = then (1 - ) ≤ ≤ .
Proof :-By lemma 2 we get,
(1- ) ≤ ≤
Given lim = and lim =
(1 - ) ≤ ≤
* * * * * * * * * * * * * * * * * * * * * * * * * * *
Preposition 4 :-
Given any sequence { } with 0< <1,there is a sequence { } of subsets of [0,1] such that
,m( ) = and S = ∩ is Cantor like set with
m(S) = .
5. On the Construction of Cantor like Sets
www.theijes.com The IJES Page 53
Proof :-
Let I = [0,1]
First stage :
We remove middle open intervals of length from [0,1]
i.e. intervals = ( , ).
The remaining two closed intervals are denoted by = [0, ] and = [ ,1 ].We get the set =
with measure ) i.e.m( ) = )
Second stage :
Now we remove two middle open intervals of length ) from the remaining two
closed intervals and i.e. we remove = ( , ) and
= ( , ).The remaining four closed intervals are denoted by
= [0, ] , = [ , ] ,
= [ , ] , = [ ,1 ].
Length of removed intervals = m( ) + m( ) = ) < )
We get the set as union of remaining four closed intervals i.e. = with measure
i.e.m( ) =
Third stage :
Now we remove four middle open intervals , , , of length from the
remaining four closed intervals , , and i.e. we remove
, = ( , ),
= ( , ),
= ( , ),
= ( , )
The remaining four closed intervals are denoted by = [ 0, ],
=[ , ], = [ , ],
= [ , ], = [ , ],
= [ , ],
= [ , ], = [ , 1 ]
6. On the Construction of Cantor like Sets
www.theijes.com The IJES Page 54
Now,
Length of removed interval = m( )+m( )+m( )+m( )
= < .
We get the set = with measure
i.e. m( ) = .
Continuing in this way we can construct , n ≥ 4 of measure
۰۰۰۰۰۰ .
m( ) = ۰۰۰۰۰۰ = )
Then S4 .
If S = then m(S) =
= )
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Conclusion :- Using this Cantor like set we can construct different Cantor like sets by varying or fixing .
REFERENCES:-
[1] G.de. Barra, “Measure Theory And Integration”, New Age International (p) Limited, 2003.
[2] Kenneth Falconer, “Fractal Geometry: Mathematical Foundations and Applications”, John Willey and Sons.1990.
[3] Kannan V. “Cantor set: From Classical To Modern”. The Mathematical Student, Vol 63,No.1-4(1994)P.243-257.
[4] E. C. Titchmarsh ,“The Theory Of Functions”, Oxford University Press, Oxford Second Edition -1987.