Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Science and Education Publishing
Turkish Journal ofAnalysis and Number Theory
Scan to view this journalon your mobile device
ISSN : 2333-1100(Print) ISSN : 2333-1232(Online)
Volume 3, Number 3, 2015
http://tjant.hku.edu.tr
Hasan Kalyoncu University
http://www.sciepub.com/journal/tjant
Turkish Journal of Analysis and Number Theory
Owner on behalf of Hasan Kalyoncu University: Professor Tamer Yilmaz, Rector
Correspondence address: Science and Education Publishing.
Department of Economics, Faculty of Economics,
Administrative and Social Sciences, TR-27410
Gaziantep, Turkey.
Web address: http://tjant.hku.edu.tr
http://www.sciepub.com/journal/TJANT
Publication type: Bimonthly
Turkish Journal of Analysis and Number Theory ISSN (Print): 2333-1100 ISSN (Online): 2333-1232 http://www.sciepub.com/journal/TJANT
Editor-in-Chief
Mehmet Acikgoz University of Gaziantep, Turkey
Feng Qi Henan Polytechnic University, China
Cenap Özel Dokuz Eylül University, Turkey
Assistant Editor
Serkan Araci Hasan Kalyoncu University, Turkey
Erdoğan Şen Namik Kemal University, Turkey
Honorary Editors
R. P. Agarwal Kingsville, TX, United States
M. E. H. Ismail University of Central Florida, United States
Tamer Yilmaz Hasan Kalyoncu University, Turkey
H. M. Srivastava Victoria, BC, Canada
Editors
Henry W. Gould West Virginia University, United States
Toka Diagana Howard University, United States
Abdelmejid Bayad Université d'éry Val d'Essonne, France
Hassan Jolany Université de Lille 1, France
István Mező Nanjing University of Information Science and Technology, China
C. S. Ryoo Hannam University, South Korea
Junesang Choi Dongguk University, South Korea
Dae San Kim Sogang University, South Korea
Taekyun Kim Kwangwoon University, South Korea
Guotao Wang Shanxi Normal University, China
Yuan He Kunming University of Science and Technology, China
Aleksandar Ivıc Katedra Matematike RGF-A Universiteta U Beogradu, Serbia
Cristinel Mortici Valahia University of Targoviste, Romania
Naim Çağman University of Gaziosmanpasa, Turkey
Ünal Ufuktepe Izmir University of Economics, Turkey
Cemil Tunc Yuzuncu Yil University, Turkey
Abdullah Özbekler Atilim University, Turkey
Donal O'Regan National University of Ireland, Ireland
S. A. Mohiuddine King Abdulaziz University, Saudi Arabia
Dumitru Baleanu Çankaya University, Turkey
Ahmet Sinan CEVIK Selcuk University, Turkey
Erol Yılmaz Abant Izzet Baysal University, Turkey
Hünkar Kayhan Abant Izzet Baysal University, Turkey
Yasar Sozen Hacettepe University, Turkey
I. Naci Cangul Uludag University, Turkey
İlkay Arslan Güven University of Gaziantep, Turkey
Semra Kaya Nurkan University of Uşak, Turkey
Ayhan Esi Adiyaman University, Turkey
M. Tamer Kosan Gebze Institute of Technology, Turkey
Hanifa Zekraoui Oum-El-Bouaghi University, Algeria
Siraj Uddin University of Malaya, Malaysia
Rabha W. Ibrahim University of Malaya, Malaysia
Adem Kilicman University Putra Malaysia, Malaysia
Armen Bagdasaryan Russian Academy of Sciences, Moscow, Russia
Viorica Mariela Ungureanu University Constantin Brancusi, Romania
Valentina Emilia Balas “Aurel Vlaicu” University of Arad, Romania
R.K Raina M.P. Univ. of Agriculture and Technology, India
M. Mursaleen Aligarh Muslim University, India
Vijay Gupta Netaji Subhas Institute of Technology, India
Hemen Dutta Gauhati University, India
Akbar Azam COMSATS Institute of Information Technology, Pakistan
Moiz-ud-din Khan COMSATS Institute of Information Technology, Pakistan
Roberto B. Corcino Cebu Normal University, Philippines
Turkish Journal of Analysis and Number Theory, 2015, Vol. 3, No. 3, 75-77
Available online at http://pubs.sciepub.com/tjantr/3/3/1
© Science and Education Publishing
DOI:10.12691/tjant-3-3-1
Backward Orbit Conjecture for Lattès Maps
Vijay Sookdeo*
Department of Mathematics, The Catholic University of America, Washington, DC
*Corresponding author: [email protected]
Received March 05, 2015; Accepted May 16, 2015
Abstract For a Lattès map 1 1: defined over a number field K, we prove a conjecture on the integrality
of points in the backward orbit of ( )P K under .
Keywords: backward orbit conjecture, Lattès maps
Cite This Article: Vijay Sookdeo, “Backward Orbit Conjecture for Lattès Maps.” Turkish Journal of
Analysis and Number Theory, vol. 3, no. 3 (2015): 75-77. doi: 10.12691/tjant-3-3-1.
1. Introduction
Let 1 1: P be a rational map of degree 2
defined over a number field ,K and write n for the
nth iterate of . For a point 1,P let
2, , ,...P P P P be the forward orbit of P
under , and let
0
n
n
P P
be the backward orbit of P under . We say P is
-preperiodic if and only if P is finite.
Viewing the projective line 1 as 1 and
taking 1 ,P K a theorem of Silverman [4] states
that if is not a fixed point for 2 , then P
contains at most finitely many points in ,K the ring of
algebraic integers in .K If S is the set of all
archimedean places for ,K then K is the set of points
in 1 K which are S-integral relative to (see section
2). Replacing with any point 1Q K and S with
any finite set of places containing all the archimedean
places, Silverman's Theorem can be stated as: If Q is not
a fixed point for 2 , then P contains at most
finitely many points which are S-integral relative to .Q
A conjecture for finiteness of integral points in
backward orbits was stated in [[6], Conj. 1.2].
Conjecture 1.1. If 1( )Q K is not S-preperiodic, then
P contains at most finitely many points in 1( )K
which are S-integral relative to .Q
In [6], Conjecture 1.1 was shown true for the powering
map dz z with degree 2,d and consequently
for Chebyschev polynomials. A gener-alized version of
this conjecture, which is stated over a dynamical family of
maps , is given in [[1], Sec. 4]. Along those lines, our
goal is to prove a general form of Conjecture 1.1 where
is the family of Lattès maps associate to a fixed
elliptic curve E defined over K (see Section 3).
2. The Chordal Metric and Integrality
2.1. The Chordal Metric on .N Let KM be the set
of places on K normalized so that the product formula
holds: for all *,K
1.v
v MK
For points 0 1: : : NP x x x and
0 1: : : NQ y y y in ( ),NvK define the v-adic
chordal metric as
,max
, .max .max
i j i j j i vv
i i i iv v
x y x yP Q
x y
Note that v is independent of choice of projective
coordinates for P and Q, and 0 , 1v (see [2]).
2.2. Integrality on Projective Curves. Let C be an
irreducible curve in N defined over K and S a finite
subset of KM which includes all the archimedean places.
A divisor on C defined over K is a finite formal sum
i in Q with in and .iQ C K The divisor is
76 Turkish Journal of Analysis and Number Theory
effective if 0in for each i, and its support is the set
Supp(D) = 1, , .Q Ql
Let , log ,Q v vP P Q and
, ,D v i Q viP n P when .i iD n Q This makes
,D v an arithmetic distance function on C (see [3]) and
as with any arithmetic distance function, we may use it to
classify the integral points on C.
For an effective divisor i iD n Q on C defined over
K , we say P C K is S-integral relative to D, or P is a
(D, S)-integral point, if and only if ,
0Q vi
P for
all embeddings , : K K and for all places .v S
Furthermore, we say the set C K is S-integral
relative to D if and only if each point in is S-integral
relative to D.
As an example, let C be the projective line 1 ,
S be the Archimedean place of ,K and .D
For / ,P x y with x and y are relatively prime in ,
we have , logD v vP y for each prime v. Therefore,
P is S-integral relative to D if and only if 1;y that is,
P is S-integral relative to D is and only if .P
From the definition we find that if 1 2S S are finite
subsets of KM which contains all the archimedean
places, then P is a 2,D S -integral point implies that P is
a 1,D S -integral point. Similarly, if Supp 1D
Supp 2D , then P is a 2 ,D S -integral point implies that
P is also a 2 ,D S -integral point. Therefore enlarging S
or Supp(D) only enlarges the set of ,D S -integrals points
on .C K
For 1 2: C C a finite morphism between projective
curves and 2 ,P C write
*
1Q P
P e Q Q
where 1e Q is the ramification index of at Q.
Furthermore, if i iD n Q is a divisor on C, then we
define * * .i iD n Q
Theorem 2.1 (Distribution Relation). Let 1 2: C C be
a finite mor-phism between irreducibly smooth curves in
( ).N K Then for 1,Q C there is a finite set of places S,
depending only on and containing all the archimedean
places, such that , * ,P v P v for all .v S
Proof. See [[3], Prop. 6.2b] and note that for projective
varieties the W V term is not required, and that the
big-O constant is an KM -bounded constant not
depending on P and Q.
Corollary 2.2. Let 1 2: C C be a finite morphism
between irreducibly smooth curves in ( ),N K let
1( ),P C K and let D be an effective divisor on C2 defined
over K. Then there is a finite set of places S, depending
only on and containing all the archimedean places,
such that P is S-integral relative to D if and only P is
S-integral relative to * .D
Proof. Extend S so that the conclusion of Theorem 2.1
holds. Then for i iD n Q with each 0in and
2 ( ),iQ C K we have that.
* , ,,.D v i Q viD v
P P n P
So * ,0
D vP
if and only if , 0.Q vi
P
3. Main Result
Let E be an elliptic curve, : E E a morphism, and
1: E be a finite covering. A Lattès map is a
rational map 1 1: making the following diagram
commute:
For instance, if E is defined by the Weierstrass
equation 2 3 2 ,y x ax bx c [2] is the
multiplication-by-2 endomorphism on E, and
, ,x y x then
4 2 2
3 2
2 8 4.
4 4 4 4
x bx cx b acx
x ax bx c
Fix an elliptic curve E defined over a number field K,
and for 1( )P K define:
1 1 1
:
: cov :
there exist K morphosm E E
and finite ering E such
that
0 P
1
0 ( ) preperK
A point Q is -preperiodic if and only if Q is -
preperiodic for some . We write 1( ) preperK
for the set of -preperiodic points in 1( ).K
Turkish Journal of Analysis and Number Theory 77
Theorem 3.1. If 1( )Q K is not -periodic, then
contains at most finitely many points in 1( )K which are
S-integral relative to Q.
Proof. Let 0 be the End(E)-submodule of ( )E K that
is finitely generated by the points in 1 ,P and let
0( ) for some non-zero End .E K E
Then 1 . Indeed, if is not -
preperiodic, then is non torsion and 1 0
for some Lattès map 1 . So 1 0 for some
morphism 1 : ,E E and this gives 1 2 P
for some Lattès map 2 . Therefore 11 2 P
12 P for some morphism 2 : .E E Since
any morphism : E E is of the form
X X T where End E and torsT E
(see [[5], 6.19]), we find that there is a End E such
that is in 0 , the End(E)-submodule generated by
1 .P Otherwise, if is -preperiodic, then
1( ) prepertors
E K K ([[5], Prop. 6.44]) gives
that may be a torsion point; again since
.tors
E K Hence 1 .
Let D be an effective divisor whose support lies entirely
in 1 ,Q let Q be the set of points in which are
S-integral relative to Q, and let D be the set of points in
which are S-integral relative to D. Extending S so that
Theorem 2.1 holds for the map 1: E , and since
Supp(D) Supp *D , we have: if is S-integral
relative to Q, then 1 is S-integral relative to D.
Therefore 1Q D . Now is a finite map and
1( );E K K so to complete the proof, it suffices
to show that D can be chosen so that D is finite.
From [[5], Prop. 6.37], we find that if is a nontrivial
subgroup of Aut(E), then 1E and the map
: E can be determine explicitly. The four
possibilities for , which are 2 3, , , ,x y x x x or y
correspond respectively to the four possibilities for ,
which are 2 4 6, , , or 3 , which in turn depends
only on the j-invariant of E. (Here, N denotes the Nth
roots of unity in .)
First assume that ,x y y . Since Q is not [']-
preperiodic, take 1 Q to be non torsion. Then
1 Q since 2 4 6, , ,or and
2 is non-torsion. Taking ,D
[[1], Thm. 3.9(i)] gives that D is finite.
Suppose that , .x y y Then , , ,x y
where 0 and is non-torsion since Q is
not -preperiodic. Assuming that both and
are torsion give that 3 is torsion, and this
contradicts the fact that is torsion. Therefore, we may
assume that is non-torsion. Now taking
,D [[1], Thm. 3.9(i)] again gives that D is
finite. Hence RQ, the set of points in which are S-
integral relative to Q, is finite.
References
[1] David Grant and Su-Ion Ih, Integral division points on curves,
Compositio Math-ematica 149 (2013), no. 12, 2011-2035.
[2] Shu Kawaguchi and J. H. Silverman, Nonarchimedean green
functions and dynam-ics on projective space, Mathematische
Zeitschrift 262 (2009), no. 1, 173-197.
[3] J. H. Silverman, Arithmetic distance functions and height
functions in Diophantine geometry, Mathematische Annalen 279
(1987), no. 2, 193-216.
[4] Integer points, Diophantine approximation, and iteration of
rational maps, Duke Math. J. 71 (1993), no. 3, 793-829.
[5] The arithmetic of dynamical systems, Graduate Text in
Mathematics 241, Springer, New York, 2007.
[6] V. A. Sookdeo, Integer points in backward orbits, J. Number
Theory 131 (2011), no. 7, 1229-1239.
Turkish Journal of Analysis and Number Theory, 2015, Vol. 3, No. 3, 78-82
Available online at http://pubs.sciepub.com/tjant/3/3/2
© Science and Education Publishing
DOI:10.12691/tjant-3-3-2
Occasionally Weakly Compatible Mappings
Amit Kumar Govery1,*
, Mamta Singh2
1School of Studies in Mathematics, Vikram University, Ujjain - 456010 (M.P.), India 2Department of Mathematical Science and Computer Application, Bundelkhand University, Jhansi (U.P.), India
*Corresponding author: [email protected]
Received March 11, 2015; Accepted May 19, 2015
Abstract In this paper, the concept of compatible maps of type (A) and occasionally weakly compatible maps in
fuzzy metric space have been applied to prove common fixed point theorem. A fixed point theorem for six self maps
has been established using the concept of compatible maps of type (A) and occasionally weakly compatible maps,
which generalizes the result of Cho [16].
Keywords: common fixed points, fuzzy metric space, compatible maps, compatible maps of type (A) and
occasionally weakly compatible maps
Cite This Article: Amit Kumar Govery, and Mamta Singh, “Occasionally Weakly Compatible Mappings.”
Turkish Journal of Analysis and Number Theory, vol. 3, no. 3 (2015): 78-82. doi: 10.12691/tjant-3-3-2.
1. Introduction
The concept of Fuzzy sets was initially investigated by
Zadeh [13] as a new way to represent vagueness in
everyday life. Subsequently, it was developed by many
authors and used in various fields. To use this concept in
Topology and Analysis, several researchers have defined
Fuzzy metric space in various ways. In this paper we deal
with the Fuzzy metric space defined by Kramosil and
Michalek [11] and modified by George and Veeramani
[20]. Recently, Grebiec [1] has proved fixed point results
for Fuzzy metric space. In the sequel, Singh and Chauhan
[12] introduced the concept of compatible mappings of
Fuzzy metric space and proved the common fixed point
theorem. Jungck et. al. [2] introduced the concept of
compatible maps of type (A) in metric space and proved
fixed point theorems. Using the concept of compatible
maps of type (A), Jain et. al. [18] proved a fixed point
theorem for six self maps in a fuzzy metric space. Singh et.
al. [7,8] proved fixed point theorems in a fuzzy metric
space. Recently in 2012, Jain et. al. [4,5] and Sharma et. al.
[6] proved various fixed point theorems using the concepts
of semi-compatible mappings, property (E.A.) and
absorbing mappings. The concept of occasionally weakly
compatible mappings in metric spaces is introduced by Al-
Thagafi and Shahzad [14] which is most general among
all the commutativity concepts. Recently, Khan and
Sumitra [15] extended the notion of occasionally weakly
compatible maps to fuzzy metric space.
In this paper, a fixed point theorem for six self maps
has been established using the concept of compatible maps
of type (A) occasionally weakly compatible mappings,
which generalizes the result of Cho [16].
For the sake of completeness, we recall some
definitions and known results in Fuzzy metric space.
2. Definitions, lemmas, Remarks,
Propositions
Definition 2.1. [10] A binary operation :
0,1 0,1 0,1 is called a -norm if is an
abelian topological monoid with unit such that
a b c d . Whenever a c and b d for .
[0,1].
Examples of -norms are:
Definition 2.2. [10] The -tuple is said to be a
Fuzzy metric space if X is an arbitrary set, is a
continuous t-norm and M is a Fuzzy set in 2 0,x
satisfying the following conditions:
For all and
(FM-1) (FM-2) (FM-3) (FM-4) (FM-5)
(FM-6)
Note that can be considered as the degree of
nearness between x and y with respect to t. We identify
with for all The following
example shows that every metric space induces a Fuzzy
metric space.
Example 2.1. [10] Let be a metric space. Define
and
, ,,
tM x y t
t d x y
for all
, and 0x y X t . Then is a Fuzzy metric space.
It is called the Fuzzy metric space induced by .
Turkish Journal of Analysis and Number Theory 79
Definition 2.3. [10] A sequence nx in a Fuzzy metric
space is said to be a Cauchy sequence if and only
if for each , there exists 0n N such that
for all .
The sequence is said to converge to a point in
if and only if for each there exists
such that for all .
A Fuzzy metric space is said to be complete if
every Cauchy sequence in it converges to a point in it.
Definition 2.4. [12] Self mappings and of a Fuzzy
metric space are said to be compatible if and only
if for all , whenever
is a sequence in such that for some in
as .
Definition 2.5. [18] Self maps and of a Fuzzy metric
space are said to be compatible maps of type
if 1and 1 for
all , whenever is a sequence in such that
for some in as Definition 2.6. [15] Two maps and from a Fuzzy
metric space into itself are said to be
Occasionally weakly compatible (owc) if and only if there
is a point , which is coincidence point of and at
which and commute.
Remark 2.1. [18] The concept of compatible maps of type
) and occasionally weakly compatibility is more general
than the concept of compatible maps in a Fuzzy metric
space.
Proposition 2.1. [18] In a Fuzzy metric space
limit of a sequence is unique.
Lemma 2.1. [1] Let be a fuzzy metric space.
Then for all , is a non-decreasing
function.
Lemma 2.2. [16] Let be a fuzzy metric space. If
there exists such that for all
Lemma 2.3. [18] Let be a sequence in a fuzzy metric
space . If there exists a number such
that and
. Then is a Cauchy sequence in .
Proposition 2.2. [18] Let and be concept of
compatible maps of type ) of a complete fuzzy metric
space with continuous t-norm defined by
for all and
for some in . Then Lemma 2.4. [3] The only -norm satisfying
for all is the minimum -norm, that is for all
3. Main Result
Theorem 3.1. Let be a complete fuzzy metric
space and let and be mappings from into
itself such that the following conditions are satisfied:
(a) (b) (c) either or is continuous;
(d) is compatible maps of type and is
occasionally weakly compatible ;
(e) there exists such that for every
and
( , , ) ( , ,* ( , , )
* ( , , * ( , , ).
M Px Qy qt M ABx STy M Px ABx t v
M Qy STy t M Px STy t
Then and have a unique common fixed
point in .
Proof: Let ∈ X. From (a) there exist such
that and .
Inductively, we can construct sequences and in such that and
Step 1. Put and in (e), we get
2 2 1
2 2 1 2 2
2 1 2 1 2 2 1
2 2 1 2 1 2
2 2 2 1 2 1 2 1
2 2 1 2 1 2 2
, ,
, , * , ,
* , , * ( , , ).
, , * , ,
* , , * , ,
( , , )* ( , , ).
n n
n n n n
n n n n
n n n n
n n n n
n n n n
M Px Qx qt
M ABx STx t M Px ABx t
M Qx STx t M Px STx t
M y y t M y y t
M y y t M y y t
M y y t M y y t
From lemma 2.1 and 2.2, we have
Similarly, we have
Thus, we have
1 1
2 1
1 2
( , , ) ( , , / )
( , , / 2)
... ... ... ...
( , , / ) 1 ,
n n n n
n n
n
M y y t M y y t q
M y y t q
M y y t q asn
and hence as for any .
For each and , we can choose
such that
for all .
For , we suppose . Then we have
1
1 2
1
( , , ) ( , , / )
* ( , , /
* * ( , , /
1 * 1 * * 1
( , , ) (1 )
n m n n
n n
m m
n m
M y y t M y y t m n
M y y t m n
M y y t m n
m n times
M y y t
and hence is a Cauchy sequence in .
Since is complete, converges to some
point . Also its subsequence’s converges to the
same point i.e.
i.e., and (1)
and (2)
80 Turkish Journal of Analysis and Number Theory
Case I. Suppose is continuous.
Since is continuous, we have
and
As is compatible pair of type , we have
Step 2. Put and in (e), we get
2 2 1
2 2 1 2 2
2 1 2 1 2 2 1
, ,
( , , )* ( , , )
* , , * ( , , ).
n n
n n n n
n n n n
M PABx Qx qt
M ABABx STx t M PABx ABABx t
M Qx STx t M PABx STx t
Taking , we get
( , , ) ( , , )* ( , ,
* ( , , )* ( , , )
( , , )* ( , , )
M ABz z qt M ABz z t M ABz ABz
M z z t M ABz z t
M ABz z t M ABz z t
Therefore, by using lemma 2.2, we get
(3)
Step 3. Put and in (e), we have
2 1
2 1
2 1 2 1 2 1
( , ,
( , , )* ( , , )
* , , * ( , , ).
n
n
n n n
M Pz Qx qt
M ABz STx t M Pz ABz t
M Qx STx t M Pz STx t
Taking and using equation (1), we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )
( , , )* ( , , )
M Pz z qt M z z t M Pz z t
M z z t M Pz z t
M Pz z t M Pz z t
i.e. Therefore, by using lemma 2.2, we get
Therefore,
Step 4. Putting and in condition (e),
we get
2 1
2 1
2 1 2 1 2 1
( , , )
( , , )* ( , , )
* , , * ( , , ).
n
n
n n n
M PBz Qx qt
M ABBz STx t M PBz ABBz t
M Qx STx t M PBz STx t
As , so we have
( )( )
( )( ) ( ) .
P Bz B Pz Bzand AB Bz
BA Bz B ABz Bz
Taking and using (1), we get
( , , )
( , , )* ( , , )* ( , , )* ( , , )
( , , )* ( , , )
M Bz z qt
M Bz z t M Bz Bz t M z z t M Bz z t
M Bz z t M Bz z t
i.e. Therefore, by using lemma 2.2, we get
and also we have
Therefore,
Az Bz Pz z (4)
Step 5. As , there exists such that
.
Putting and in (e), we get
2
2 2 2
( , , )
( , , )* ( , , )
* , , * ( 2 , , ).
n
n n n
M Px Qu qt
M ABx STu t M Px ABx t
M Qu STu t M Px n STu t
Taking and using (1) and (2), we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )* ( , , )
( , , )
M z Qu qt M z z t M z z t
M Qu z t M z z t M z z t
M Qu z t
i.e. Therefore, by using lemma 2.2, we get Hence
Since is occasionally weakly
compatible, therefore, by proposition (2.2), we have
Thus
Step 6. Putting and in (e), we get
2
2 2 2
2
, ,
, , * ( , , )
* , , * ( , , ).
n
n n n
n
M Px Qz qt
M ABx STz t M Px ABx t
M Qz STz t M Px STz t
Taking and using (2) and step 5, we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )
( , , )* ( , , )
M z Qz qt M z Qz t M z z t
M Qz Qz t M z Qz t
M z Qz t M z Qz t
Therefore, by using lemma 2.2, we get
Qz = z.
Step 7. Putting and in (e), we get
2
2 2 2
2
( , , )
( , , )* ( , , )
* , , * ( , , ).
n
n n n
n
M Px QTz qt
M ABx STTz t M Px ABx t
M QTz STTz t M Px STTz t
As and , we have
and ( ) ( ) .
QTz TQz Tz
ST Tz T STz TQz Tz
Taking , we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )
( , , )* ( , , )
M z Tz qt M z Tz t M z z t
M Tz Tz t M z Tz t
M z Tz t M z Tz t
i.e.
Therefore, by using lemma 2.2, we get
Now implies
Hence
.Sz Tz Qz z (5)
Combining (4) and (5), we get
.Az Bz Pz Qz Tz Sz z
Hence, is the common fixed point of and
.
Turkish Journal of Analysis and Number Theory 81
Case II. Suppose is continuous.
As is continuous,
and
As is compatible pair of type ,
Step 8. Putting and in condition
(e), we have
2 2 1
2 2 1 2 2
2 1 2 1 2 2 1
( , , )
( , , )* ( , , )
* , , * ( , , ).
n n
n n n n
n n n n
M PPx Qx qt
M ABPx STx t M PPx ABPx t
M Qx STx t M PPx STx t
Taking , we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )
( , , )* ( , , )
M Pz z qt M Pz z t M Pz Pz t
M z z t M Pz z t
M Pz z t M Pz z t
i.e. Therefore by using lemma 2.2, we have
Further, using steps 5,6,7, we get
Step 9. As , there exists such that
Put and in (e), we get
2 1
2 1
2 1 2 1 2 1
( , , )
( , , )* ( , , )
* , , * ( , , ).
n
n
n n n
M Pw Qx qt
M ABw STx t M Pw ABw t
M Qx STx t M Pw STx t
Taking , we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )
( , , )* ( , , )
M Pw z qt M z z t M Pw z t
M z z t M Pw z t
M Pw z t M Pw z t
i.e. Therefore, by using lemma 2.2, we get
Therefore,
As is compatible pair of type , then by
proposition (2.2), we have
Also, from step 4, we get .
Further, using steps 5, 6, 7, we get
i.e. is the common fixed point of the six maps
and in this case also.
Uniqueness: Let be another common fixed point of
and .
Then .
Put and in (e), we get
, , , , * , ,
* ( , , )* ( , , ).
M Pz Qu qt M ABz STu t M Pz ABz t
M Qu STu t M Pz STu t
Taking , we get
( , , ) ( , , )* ( , , )
* ( , , )* ( , , )
( , , )* ( , , )
M z u qt M z u t M z z t
M u u t M z u t
M z u t M z u t
i.e. Therefore by using lemma (2.2), we get .
Therefore is the unique common fixed point of self
maps and .
Remark 3.1. If we take , the identity map on
in theorem 3.1, then condition is satisfied trivially
and we get
Corollary 3.1. Let be a complete fuzzy metric
space and let and be mappings from into itself
such that the following conditions are satisfied:
(a) ;
(b) either or is continuous;
(c) is compatible maps of type and is
occasionally weakly compatible;
(d) there exists such that for every
and
( , , ) ( , , )* ( , , )
* ( , , )* ( , , ).
M Px Qy qt M Ax Sy t M Px Ax t
M Qy Sy t M Px Sy t
Then and have a unique common fixed point
in .
Remark 3.2. In view of remark 3.1, corollary 3.1 is a
generalization of the result of Cho [16] in the sense that
condition of compatibility of the pairs of self maps has
been restricted to compatibility of type occasionally
weakly compatible and only one map of the first pair is
needed to be continuous.
Acknowledgement
Authors are thankful to the referee for his valuable
comments.
References
[1] George and P. Veeramani, On some results in Fuzzy metric spaces,
Fuzzy Sets and Systems 64 (1994), 395-399.
[2] Jain and B. Singh, A fixed point theorem for compatible mappings
of type (A) in fuzzy metric space, Acta Ciencia Indica, Vol.
XXXIII M, No. 2 (2007), 339-346.
[3] Jain, M. Sharma and B. Singh, Fixed point theorem using
compatibility of type (β) in Fuzzy metric space, Chh. J. Sci. &
Tech., Vol. 3 & 4, (2006- 2007), 53-62.
[4] Jain, V.H. Badshah, S.K. Prasad, Fixed Point Theorem in Fuzzy
Metric Space for Semi-Compatible Mappings, Int. J. Res. Rev.
Appl. Sci. 12 (2012), 523-526.
[5] Jain, V.H. Badshah, S.K. Prasad, The Property (E.A.) and The
Fixed Point Theorem in Fuzzy Metric, Int. J. Res. Rev. Appl. Sci.
12 (2012), 527-530.
[6] Sharma, A. Jain, S. Chaudhary, A note on absorbing mappings and
fixed point theorems in fuzzy metric space, Int. J. Theoretical
Appl. Sci. 4 (2012), 52-57.
[7] Singh, A. Jain, A.K. Govery, Compatibility of type and fixed
point theorem in Fuzzy metric space, Appl. Math. Sci. 5 (2011),
517-528.
[8] Singh, A. Jain, A.K. Govery, Compatibility of type (A) and fixed
point theorem in Fuzzy metric space,Int. J. Contemp. Math. Sci. 6
(2011), 1007-1018.
[9] Singh and M.S. Chouhan, Common fixed points of compatible
maps in Fuzzy metric spaces, Fuzzy sets and systems, 115 (2000),
471-475.
82 Turkish Journal of Analysis and Number Theory
[10] E.P. Klement, R. Mesiar and E. Pap, Triangular Norms, Kluwer
Academic Publishers.
[11] G. Jungck, P.P. Murthy and Y.J. Cho, Compatible mappings of
type (A) and common fixed points, Math. Japonica, 38 (1993),
381-390.
[12] I.Kramosil and J. Michalek, Fuzzy metric and statistical metric
spaces, Kybernetica 11(1975), 336-344.
[13] L. A. Zadeh, Fuzzy sets, Inform and control 89 (1965), 338-353.
[14] M.A. Al-Thagafi, N.A. Shahzad, A note on occasionally weakly
compatible maps, Int. J. Math. anal. 3(2009), 55-58.
[15] M.A. Khan, Sumitra, Common fixed point theorems for
occasionally weakly compatible maps in fuzzy metric spaces, Far
East J. Math. Sci., 9 (2008), 285-293.
[16] S.H., Cho, On common fixed point theorems in fuzzy metric spaces,
J. Appl. Math. & Computing Vol. 20 (2006), No. 1-2, 523-533.
[17] S.N. Mishra, N. Mishra and S.L. Singh, Common fixed point of
maps in fuzzy metric space, Int. J. Math. Math. Sci. 17(1994), 253-
258.
[18] M. Grebiec, Fixed points in Fuzzy metric space, Fuzzy sets and
systems, 27(1998), 385-389.
[19] Y.J. Cho, Fixed point in Fuzzy metric space, J. Fuzzy Math.
5(1997), 949-962.
[20] Y.J. Cho, H.K. Pathak, S.M. Kang and J.S. Jung, Common fixed
points of compatible mappings of type (β) on fuzzy metric spaces,
Fuzzy sets and systems, 93 (1998), 99-111.
Turkish Journal of Analysis and Number Theory, 2015, Vol. 3, No. 3, 83-86
Available online at http://pubs.sciepub.com/tjant/3/3/3
© Science and Education Publishing
DOI:10.12691/tjant-3-3-3
Coefficient Estimates for Starlike and Convex Classes of
-fold Symmetric Bi-univalent Functions
S. Sivasubramanian1, P.Gurusamy
2,*
1Department of Mathematics, University College of Engineering Tindivanam, Anna University, Tindivanam, India 2Department of Mathematics, Velammal Engineering College, Surapet, Chennai, India
*Corresponding author: [email protected]
Received March 16, 2015; Accepted May 24, 2015
Abstract In an article of Pommerenke [10] he remarked that, for an -fold symmetric functions in the class ,
the well known lemma stated by Caratheodary for a one fold symmetric functions in still holds good. Exploiting
this concept, we introduce certain new subclasses of the bi-univalent function class in which both and are
-fold symmetric analytic with their derivatives in the class of analytic functions. Furthermore, for functions in
each of the subclasses introduced in this paper, we obtain the coefficient bounds for and We remark
here that the concept of -fold symmetric bi-univalent is not in the literature and the authors hope it will make the
researchers interested in these type of investigations in the forseeable future. By the working procedure and the
difficulty involved in these procedures, one can clearly conclude that there lies an unpredictability in finding the
coefficients of a -fold symmetric bi-univalent functions.
Keywords: analytic functions, univalent functions, bi-univalent functions, -fold symmetric functions,
subordination
Cite This Article: S. Sivasubramanian, and P.Gurusamy, “Coefficient Estimates for Starlike and Convex
Classes of -fold Symmetric Bi-univalent Functions.” Turkish Journal of Analysis and Number Theory, vol. 3,
no. 3 (2015): 83-86. doi: 10.12691/tjant-3-3-3.
1. Introduction
Let denote the class of functions of the form:
∑
(1)
which are analytic in the open unit disk Further, by we mean the class of all functions in
which are univalent in . For more details on univalent
functions, see [3]. It is well known that every function
has an inverse , defined by
(2)
and
(
) (3)
Indeed, the inverse function may have an analytic
continuation to , with
1 2 2 3
2 2 3
3 42 2 3 4
( ) (2 )
(5 5 ) .
f w w a w a a w
a a a a w
(4)
A function is said to be bi-univalent in if both
and are univalent in . Let denote the class of bi-
univalent functions in , given by equation (1). An
analytic function is subordinate to an analytic function ,
written , provided there is an analytic
function defined on with and
satisfying . Lewin [8] investigated the
class of bi-univalent functions and obtained a bound
. Motivated by the work of Lewin [8],
Brannan and Clunie [1] conjectured that √ . Some
examples of bi-univalent functions are
(
) and
(see also the work of Srivastava et al. [11]).
The coefficient estimate problem for each of the following
Taylor-Maclaurin coefficients: is
still open([11]). In recent times, the study of bi-univalent
functions gained momentum mainly due to the work of
Srivastava et al. [11]. Motivated by this, many researchers
(see [4,11,12,13,14,15,17]) recently investigated several
interesting subclasses of the class and found non-sharp
estimates on the first two Taylor-Maclaurin coefficients.
For each function in , the function √ is
univalent and maps the unit disk into a region with -
fold symmetry. A function is -fold symmetric (see [10])
if it has the normalized form
∑
(5)
and we denote the class of -fold symmetric univalent
functions by , which are normalized by the above series
expansion. In fact, the functions in the class are one fold
symmetric. Analogous to the concept of -fold symmetric
univalent functions, one can think of the concept of -
fold symmetric bi-univalent functions in a natural way.
Each function in the class in , generates an -fold
symmetric bi-univalent function for each integer . The
normalized form of is given as in (5) and is given as
follows.
84 Turkish Journal of Analysis and Number Theory
1 2 2 11 1 2 1
31 3 1
1 2 1 3 1
( ) ( 1)
1( 1)(3 2)
.2
(3 2)
m mm m m
m m
m m m
g w w a w m a a w
m m aw
m a a a
(6)
where . We denote the class of -fold symmetric
bi-univalent functions by . For , the formula (6)
coincides with the formula (4) of the class Denote also,
by , the class of analytic functions of the form
such that ( ) in . In
view of Pommerenke [10], the -fold symmetric function
in the class is of the form
(7)
It is assumed that is an analytic functions with
positive real part in the unit disk , with and is symmetric with respect to the
real axis. Such a function has a series expansion of the
form
(8)
Suppose that and are analytic functions in
the unit disk with and , and suppose that
(9)
and
(10)
We observe that
2 2
2 21, 1 , 1and 1 .m m m m m mb b b c c c (11)
By a simple computations, we have
2 21 1 2 21 ( ) ( 1)
m mm m mu z B b z B b B b z z (12)
and
2 21 1 2 21 ( ) ( 1).
m mm m mv w B c w B c B c w w (13)
Motivated essentially by the work of Ma and Minda [9],
we introduce some new subclasses of -fold symmetric
bi-univalent functions and obtain coefficient bounds of
and for functions in these classes. The
results presented in this paper improve the earlier results
of Frasin and Aouf [4], Srivastava et al. [11] for the case
of one fold symmetric functions.
2. Coefficient Estimates for the Function
Class
Definition 2.1 A function , given by (5), is said to
be in the class , if the following conditions are
satisfied:
1
',
'and ,
m
zf zf z
f z
wg ww g w f w
g w
where the function is defined by (6).
For the special choices of the function and for the
choice of our class reduces to the following.
1. For and (
)
,
( (
)
) the class of
strongly bi-starlike functions of order studied by
Brannan and Taha [2].
2. For and
,
( (
))
the class of
bi-starlike functions of order studied by Brannan and
Taha [2].
We first state and prove the following theorem.
Theorem 2.1 Let given by (5), be in the class
. Then
√
√ | |
(14)
and
12 12
22 11 2 1 2 1
2 12 2
1 2 1
1
2
1
2
m
m Bif B B
m
a m B B B B Bif B B
m B B B
(15)
Proof. Let and . Then there are
analytic functions , with
satisfying
( )
( ) (16)
Since
and
2
211
2 1
' 2 11 ,
2
m mmm
m
wg w m m ama w w
g w ma
it follows from (12), (13) and (16) that
(17)
(18)
(19)
and
(20)
From (17) and (19), we get
(21)
By adding (18) and (20) and in view of the
computations using (17) and (21), we get
(22)
Further, (21), (22), together with (11), gives
(23)
Now from (17) and (23), we get
Turkish Journal of Analysis and Number Theory 85
√
√ | |
as asserted in (14).
By simple calculations from (18) and (20) using with
the equations (17) and (21), we get
2 22 1 1 2 1 2 24 1 2 2 1m m m mm a m B b B c m B b (24)
Then using the equation (11) in (24), we get
(25)
Since
| |
(26)
substituting (26) in (25), we get
12 12
22 11 2 1 2 1
2 12 2
1 2 1
1
2
1
2
m
m Bif B B
m
a m B B B B Bif B B
m B B B
as asserted in (15). This completes the proof of Theorem
2.1.
For the case of one fold symmetric functions, Theorem
2.1 reduces to the coefficient estimates for Ma-Minda bi-
starlike functions in Srivastava et al [11].
Corollary 2.1 Let , given by (5), be in the class
. Then
√
√| |
(27)
and
(28)
For the case of one fold symmetric functions and for the
class of strongly starlike functions , the function is
given by
2 211 2 2 , 0 1
1
zz z z
z
(29)
which gives and . Hence Theorem 2.1
reduce to the result in Brannan and Taha [2].
Corollary 2.2 [2] Let , given by (5), be in the class
. Then
√ (30)
and
(31)
For the case of one fold symmetric functions and for the
class of strongly starlike functions , the function is
given by
then , and the Theorem 2.1 reduce to
the result in Brannan and Taha [2].
Corollary 2.3 [2] Let , given by (5), be in the class
. Then
√ (32)
and
√ (33)
3. Coefficient Bound for the Function
Class
Definition 3.1 A function , given by (5), is said to
be in the class , if the following conditions are
satisfied:
and
where the function is defined by (6).
For one fold symmetric, a function in the class
is called bi-Mocanu-convex function of Ma-
Minda type. For the special choices of the function and for the choice of our class reduces to the
following.
1. For and
( (
)
) the class of strongly bi-
convex functions of order studied by Brannan and Taha
[2].
2. For and
( (
)) the class of
bi-convex functions of order studied by Brannan and
Taha [2].
Theorem 3.1 Let given by (5), be in the class
Then
√
√ | |
(34)
and
12 12
21 2 1
2 12 1
2 121 22
1
2
1
1
12
1
m
Bif B B
m
B m B B
am B B
if B BB m B
m
m B
(35)
Proof. Let . Then there are analytic
functions , with satisfying
( )
( ) (36)
Since
1
2 2 22 1 1
''1 1 1
'
2 1 2 1
mm
mm m
zf zm m a z
f z
m m a m m a z
and
86 Turkish Journal of Analysis and Number Theory
1
21 2
2 1
''1 1 1
'
1 3 1
2 1 2
mm
m m
m
wg wm m a w
g w
m m m aw
m m a
from (12), (13), and (36), we get
(37)
2 2 2
2 1 1 1 2 22 1 2 1 ,m m m mm m a m m a B b B b (38)
(39)
and
2
1 2 1
21 2 2
1 3 1 2 1 2
.
m m
m m
m m m a m m a
B c B c
(40)
From (37) and (39), we get
(41)
By adding the equations (38) and (40), in view of
computations using (37) and (41), we get
2 2 21 2 1
31 2 2
2 1 1
.
m
m m
m m B m B a
B b c
(42)
Further, from the equations (41), (42), together with
(11), we have
22 2 2 31 2 1 11 1 1 .m mm m B m B a B b (43)
Now from (37) and (43), we get
√
√ | |
as asserted in(34). By simple calculations from (38) and
(40) using with the equations (37) and (41), we get
22 1
21 2 1 2 2
4 1 2
1 3 1 2 1 2 .
m
m m m
m m a
m B b m B c m B b
(44)
Then using the equation (11) in (44), we get
(45)
Since
| |
(46)
substituting (46) in (45), we get
12 12
22 1 1 2 1 2 1
2 12 2
1 2 1
2
1 1
2 1 1
m
Bif B B
m
a B m B B m B Bif B B
m B m B m B
as asserted in (35).
For one fold symmetric functions then, Theorem 3.1
gives the coefficient for Ma-Minda bi-convex functions in
Brannan and Taha [2]
Corollary 3.1 [2] Let , given by (5), be in the class
. Then
√
√| |
and
For the case of one fold symmetric functions and for the
class of strongly starlike functions, the function is given
by
then , and the Theorem 3.1 reduce to
the result in Brannan and Taha[2].
Corollary 3.2 [2] Let , given by (5), be in the class
. Then
and
References
[1] D. A. Brannan and J. G. Clunie, Aspects of contemporary complex
analysis, Academic Press, London, 1980.
[2] D. A. Brannan and T. S. Taha, On some classes of bi-univalent
functions, Stud.Univ.Babes-Bolyai Math. 31(1986), 70-77.
[3] P. L. Duren, Univalent functions, Springer-Verlag, New York,
Berlin, Hiedelberg and Tokyo, 1983.
[4] B. A. Frasin and M. K. Aouf, New subclasses of bi-univalent
functions, Appl. Math. Lett. 24 (2011), 1569-1573.
[5] J. Sokol, On a condition for - starlikeness, J. Math. Anal. Appl.
352(2009), 696-701.
[6] M . K . Aouf , J . Sokol and J . Dziok, On a subclass of strongly
starlike functions, Appl. Math. Lett. 24 (2011), 27-32.
[7] J . Sokol, A certain class of starlike functions, Comput. Math.
Appl, 62(2011), 611-619.
[8] M. Lewin, On a coefficient problem for bi-univalent functions,
Proc. Amer. Math. Soc. 18 (1967), 63-68.
[9] W. C. Ma, and D. Minda, A unified treatment of some special
classes of unvalent functions, in Proceedings of the Conference on
complex analysis. Tianjin (1992), 157-169.
[10] Ch.Pommerenke, On the coefficients of close-to-convex functions,
Michigan. Math. J. 9 (1962), 259-269.
[11] H. M. Srivastava, A. K. Mishra and P. Gochhayat, Certain
subclasses of analytic and bi-univalent functions, Appl. Math. Lett.
23 (2010), 1188-1192.
[12] H. M. Srivastava, S. Bulut, M. Cagler and N. Yagmur, Coefficient
estimates for a general subclass of analytic and bi-univalent
functions, Filomat. 27 (2013), 831-842.
[13] Q.-H. Xu, H. M. Srivastava and Z. Li, A certain subclass of
analytic and close-to-convex functions, Appl. Math. Lett. 24
(2011), 396-–401.
[14] Q.-H. Xu, Y.-C. Gui and H. M. Srivastava, Coefficient estimates
for a certain subclass of analytic and bi-univalent functions, Appl.
Math. Lett. 25 (2012), 990-994.
[15] Q.-H. Xu, H.-G. Xiao and H. M. Srivastava, A certain general
subclass of analytic and bi-univalent functions and associated
coefficient estimate problems, Appl. Math. Comput. 218 (2012),
11461-11465.
[16] Zhigang Peng and Qiuqiu Han, On the Coefficients of several
classes of bi-uivalent functions, Acta. Math. Sci. 34B(1) (2014),
228-240.
[17] H. Tang, G-T. Deng and S-H. Li, Coefïcient estimates for new
subclasses of Ma-Minda bi-univalent functions, J. Inequal. Appl.
2013, 2013:317, 1-10.
Turkish Journal of Analysis and Number Theory, 2015, Vol. 3, No. 3, 87-89
Available online at http://pubs.sciepub.com/tjant/3/3/4
© Science and Education Publishing
DOI:10.12691/tjant-3-3-4
Schur-geometric and Schur-harmonic Convexity of an
Integral Mean for Convex Functions
Jian Sun1, Zhi-Ling Sun
1, Bo-Yan Xi
1, Feng Qi
2,3,*
1College of Mathematics, Inner Mongolia University for Nationalities, Tongliao City, Inner Mongolia Autonomous Region, China 2Department of Mathematics, School of Science, Tianjin Polytechnic University, Tianjin City, China;
3Institute of Mathematics, Henan Polytechnic University, Jiaozuo City, Henan Province, China
*Corresponding author: [email protected]
Received April 11, 2015; Accepted June 20, 2015
Abstract In the paper, Schur-geometric and Schur-harmonic convexity of an integral mean for convex functions
are established.
Keywords: Schur-convex function; Schur-geometrically convex function; Schur-harmonically convex function;
inequality; generalized logarithmic mean
Cite This Article: Jian Sun, Zhi-Ling Sun, Bo-Yan Xi, and Feng Qi, “Schur-geometric and Schur-harmonic
Convexity of an Integral Mean for Convex Functions.” Turkish Journal of Analysis and Number Theory, vol. 3,
no. 3 (2015): 87-89. doi: 10.12691/tjant-3-3-4.
1. Introduction
In [3], N. Elezović and J. Pečarić established the
following theorem.
Theorem A ([3]). Let :f I R R and ,a b I . Then
1( )d , ,
( , )
( ),
b
af x x a b
F a b b a
f a a b
is Schur-convex (Schur-concave) on 2I if and only if f
is convex (concave) on .I
In [7,10], Theorem A was generalized as the following
theorem.
Theorem B ([7,10]). Let be a continuous function
and a positive continuous weight on an interval . Then
the weighted arithmetic mean of with weight defined
by
( ) ( )d, ,
( , )( )d
( ),
y
x
y
x
p t f t tx y
G x yp t t
f x x y
is Schur-convex (Schur-concave) on if and only if
( ) ( )d ( ) ( ) ( ) ( )
( )+ ( )( )d
y
x
y
x
p t f t t p x f x p y f y
p x p yp t t
holds (reverses) for all .
For more information on this topic, please refer to
[5,8,9] and closely-related references therein.
In this paper, we discuss Schur-geometric and Schur-
harmonic convexity of the mean and obtain two
results which generate Theorem A.
2. Definitions and Lemmas
In order to prove our main results we need the
following definitions and lemmas.
Definition 1 ([4]). Let I R and 1( , , )nx x x ,
1( , , ) ,nny y y I and let : .nI R
(1) x is said to be majorized by y (in symbols x y )
if 1 1
k ki ii i
x y
for 1,2, , 1k n and
[ ]1 1
n nii i
x y
[i] , where [1] [ ]nx x and
[ ]ny y [1] are rearrangements of x and y in a
descending order.
(2) x y means i ix y for all 1,2, , .i n is said
to be increasing if x y implies ( ) ( )x y . is said
to be decreasing if and only is increasing.
(3) is said to be a Schur-convex function on nI if
x y on nI implies ( ) ( )x y . is said to be a
Schur-concave function on nI if and only is Schur-
convex function.
Definition 2 ([1,2]). Let 1( , , )nx x x , 1( , , )ny y y
+n nI R and : nI R and let 1ln (ln , , ln ),nx x x
1 1 1
1, ,
x x xn .
(1) is said to be a Schur-geometrically convex
function on nI if ln lnx y on nI implies ( ) ( )x y .
88 Turkish Journal of Analysis and Number Theory
is said to be a Schur-geometrically concave function on
nI if and only is Schur-geometrically convex
function.
(2) is said to be a Schur-harmonically convex
function on nI if 1 1x y
on nI implies ( ) ( )x y .
is said to be a Schur-harmonically concave function on nI
if and only is Schur-harmonically convex function.
Lemma 2.1([1]). Let 2 2+: I R R be a continuous
function on 2I and differentiable in interior of 2I . Then
is Schur-geometrically convex (Schur-geometrically
concave) if and only if it is symmetric and
( )0b a b ab a
for all , .a b I
Lemma 2.2 ([2]). Let 2 2+: I R R be a
continuous function on 2I and differentiable in interior of 2I . Then is Schur-harmonically convex (Schur-
harmonically concave) if and only if it is symmetric and
2 2 ( )0b a b ab a
for all , .a b I
For two positive numbers 0a and 0b , define
( , ) ,2
( , ) ,
2( , )
a bA a b
G a b ab
abH a b
a b
and
11 1
, , 1,( , ) ( 1)( )
, .
rr r
r
b aa b r
L a b r b a
a a b
It is well known that ( , )A a b , ( , )G a b , ( , )H a b and
( , )sL a b are respectively called the arithmetic, geometric,
harmonic and generalized logarithmic means of a and .b
Lemma 2.3 ([6]) ( , )rL a b is increasing function on
2+( , )a b R .
In this paper, we will prove that the function ( , )F a b is
Schur-geometrically convex and Schur-harmonically
convex on 2+R .
3. Main Results
Theorem 3.1. Let :f I R R and F be defined in
Theorem A.
(i). If f is convex and increasing on I , then F is
Schur-geometrically convex on 2I .
(ii). If f is concave and decreasing on I , then F is
Schur-geometrically concave on 2I .
Proof. If ,a b I and a b , we have ( , ) ( ).F a a f a
For all , ,a b I a b , a straightforward computation
gives
1 1, ,
1 1, .
Ff b F a b
b b a b a
Ff a F a b
a b a b a
(3)
If f is convex and increasing on I , by the inequality
(2), we obtain
( ) ( ) ( ) ( , )
( ) ( ) ( )d
12 ( ) 2 ( ) ( )( ( ) ( ))
2
1( )( ( ) ( )) 0.
2
b
a
F Fb a b a
b a
af a bf b a b F a b
a baf a bf b f x x
b a
af a bf b a b f a f b
b a f b f a
(4)
Hence, ( , )F a b is Schur-geometrically convex on 2I . If
f is concave and decreasing on I , then the inequality (4)
is reversed. According to Lemma 2.1, it follows that
( , )F a b is Schur-geometrically concave 2I . This
completes the proof of Theorem 3.1.
Theorem 3.2. Let :f I R R and F be defined in
Theorem A.
(i). If f is convex and increasing on I , then F is
Schur-harmonically convex on 2I .
(ii). If f is concave and decreasing on I , then F is
Schur-harmonically concave on 2I .
Proof . If ,a b I and a b , we have ( , ) ( ).F a a f a
For all , ,a b I a b , if f is convex and increasing,
using inequality (3) and (2), we get
2 2
2 22 2
2 22 2
2 2
( )
( ) ( ) ( )d
( ) ( ) ( ) ( )2
1= ( ) ( ) ( ) 0.
2
b
a
F Fb a b a
b a
a ba f a b f b f x x
b a
a ba f a b f b f a f b
b a f b f a
(5)
Therefore, ( , )F a b is Schur-harmonically convex function
on 2I . If f is concave and decreasing function on I ,
then the inequality (5) is reversed. According to Lemma
2.2, it follows that ( , )F a b is Schur-harmonically concave
function on 2I . The proof of Theorem 3.2 is complete.
Turkish Journal of Analysis and Number Theory 89
4. Applications
Theorem 4.1. For 0a and 0b , if 1r , then
( , )rL a b is Schur-geometrically convex and Schur-
harmonically convex.
Proof. Taking ( ) rf x x for all x R , if a b , it
follows that
+1 +11 1( , ) ( )d d
( 1)( )
r rb b r
a a
b aF a b f x x x x
b a b a r b a
and ( ) rf x x is convex increasing on R for 1r .
Therefore, by Theorem 3.1 and 3.2, we have
+1 +1
, ,( 1)( )( , )
,
r r
r
b aa b
r b aF a b
a a b
is Schur-geometrically convex and Schur-harmonically
convex on 2R for 1r , then ( , )rL a b is Schur-
geometrically convex and Schur-harmonically convex on 2R for 1r . Thus, Theorem 4.1 is proved.
Corollary 4.1.1. For 0b a and 1r , define
(1 )au ta t b , (1 )av t a tb , 1t tgu a b ,
1 t tgv a b , 1 1(1 )hu ta t b , and
1 1(1 )hv t a tb for (0,1)t . Then
(1) when (0,1)t and 1/ 2t , we have
1/1/+1 +1( +1) ( +1)
1 1
1/+1 +1
( 1)( )( 1)( )
( , );( 1)( )
rrr rr rg gh h
g gh h
rr ra a
r
a a
u vu v
r u vr u v
u vL a b
r u v
(2) when =1/ 2t , we have
( , ) ( , ) ( , )= ( , ).rH a b G a b A a b L a b
Proof. When =1/ 2t , it is easy to obtain that
( , ) ( , ) ( , ).rH a b G a b L a b When (0,1)t and 1/ 2t ,
by Corollary 2 in [6] and Lemma 2.3, Corollary 4.1.1 is
thus proved.
Acknowledgements
The authors thank the anonymous referees for their
careful corrections to and valuable comments on the
original version of this paper.
Support
This work was partially supported by the National
Natural Science Foundation of China under Grant No.
11361038 and by the Inner Mongolia Autonomous Region
Natural Science Foundation Project under Grant No.
2015MS0123 and No. 2014BS0106, China.
References
[1] Y.-M. Chu, X.-M. Zhang, and G.-D. Wang, The Schur
geometrical convexity of the extended mean values, J. Convex
Anal. 15 (2008), no. 4, 707-718.
[2] W.-F. Xia and Y.-M. Chu, Schur-convexity for a class of
symmetric functions and its applications, J. Inequal. Appl. 2009
(2009), Article ID 493759, 15 pages.
[3] N. Elezović and J. Pečarić, A note on Schur-convex functions,
Rocky Mountain J. Math. 30 (2000), no. 3, 853-856.
[4] A. W. Marshall and I. Olkin, Inequalities: Theory of Majorization
and its Application, New York: Academies Press, 2011.
[5] C. Mortici, Arithmetic mean of values and value at mean of
arguments for convex functions, ANZIAM J. 50 (2008), no. 1,
137-141.
[6] F. Qi and Q.-M. Luo, A simple proof of monotonicity for extended
mean values, J. Math. Anal. Appl. 224 (1998), 356-359.
[7] F. Qi, J. Sándor, S. S. Dragomir, and A. Sofo, Notes on the Schur-
convexity of the extended mean values, Taiwanese J. Math. 9
(2005), no. 3, 411-420.
[8] H.-N. Shi, Schur-convex functions related to Hadamard-type
inequalities, J. Math. Inequal. 1 (2007), no. 1 127-136.
[9] H.-N. Shi, D.-M. Li and C. Gu, The Schur-convexity of the mean
of a convex function, Appl. Math. Lett. 22 (2009), no. 6, 932-937.
[10] H.-N. Shi, S.-H. Wu, and F. Qi, An alternative note on the Schur-
convexity of the extended mean values, Math. Inequal. Appl. 9
(2006), no. 2, 219-224.
Turkish Journal of Analysis and Number Theory, 2015, Vol. 3, No. 3, 90-93
Available online at http://pubs.sciepub.com/tjant/3/3/5
© Science and Education Publishing
DOI:10.12691/tjant-3-3-5
Symmetric Identities Involving q-Frobenius-Euler
Polynomials under Sym (5)
Serkan Araci1,*
, Ugur Duran2, Mehmet Acikgoz
2
1Department of Economics, Faculty of Economics, Administrative and Social Sciences, Hasan Kalyoncu University, Gaziantep,
TURKEY 2University of Gaziantep, Faculty of Science and Arts, Department of Mathematics, Gaziantep, TURKEY
*Corresponding author: [email protected]
Received April 21, 2015; Accepted June 26, 2015
Abstract Following the definition of q-Frobenius-Euler polynomials introduced in [3], we derive some new
symmetric identities under sym (5), also termed symmetric group of degree five, which are derived from the
fermionic p-adic q-integral over the p-adic numbers field.
Keywords: Symmetric identities, q-Frobenius-Euler polynomials, Fermionic p-adic q-integral on p Invariant
under S5
Cite This Article: Serkan Araci, Ugur Duran, and Mehmet Acikgoz, “Symmetric Identities Involving q-
Frobenius-Euler Polynomials under Sym (5).” Turkish Journal of Analysis and Number Theory, vol. 3, no. 3
(2015): 90-93. doi: 10.12691/tjant-3-3-5.
1. Introduction
As it is known, the Frobenius-Euler polynomials
nH x for with 1 are defined by means of
the power series expansion at 0t
0
1.
!
nxt
n tn
tH x e
n e
(1.1)
Taking x = 0 in the Eq. (1.1), we have 0 :n nH H
that is widely known as n-th Frobenius-Euler number cf.
[3,4,5,8,17,18,21]. Let p be chosen as a fixed odd prime number.
Throughout this paper, we make use of the following
notations: p denotes topological closure of ,
denotes the field of rational numbers, p denotes
topological closure of , and p indicates the field of
p-adic completion of an algebraic closure of p . Let
be the set of natural numbers and * 0 .
For d an odd positive number with (p,d) = 1, let
1: lim / Nd p
nX X dp and X
and
| modN Npa dp x X x a dp
where a lies in 0 Na dp . See, for details,
[1,2,3,4,6-17].
The normalized absolute value according to the theory
of p-adic analysis is given by 1p
p p . q can be
considered as an indeterminate a complex number q
with 1q , or a p-adic number pq with
1
11 pp
q p
and exp logxq x q for 1.p
x It is
always clear in the content of the paper. Throughout this paper, we use the following notation:
1
.1
x
q
qx
q
(1.2)
which is called q-extension of x. It easily follows that
1limq qx x for any x.
Let f be uniformly differentiable function at a point
,pa which is denoted by .pf UD Then the
p-adic q-integral on p (or sometimes called q-
Volkenborn integral) of a function f is defined by Kim [10]
1
0
1lim .
Np
xq q Np N
xq
I f f x d x f x qp
(1.3)
It follows from the Eq. (1.3) that
1 11
1
0
lim
lim 1 .
qq p
Npx
Nx
I f I f f x d x
f x
(1.4)
Turkish Journal of Analysis and Number Theory 91
Thus, by the Eq. (1.4), we have
1
1 11 1
0
1 2 1n
n n sn
s
I f I f f s
where , .nf x f x n n . For the applications of
fermionic p-adic integral over the p-adic numbers field,
see the references, e. g., [1,2,3,4,6,7,9,11,12,16]. In [3], the q-Frobenius-Euler polynomials are defined
by the following p-adic fermionic q-integral on p , with
respect to 1 :
1,
1
|
1.
2
n q
nyq
p
H x
x y d y
(1.5)
Upon setting x = 0 into the Eq. (1.5) gives
, ,0 :n q n qH H which are called n-th q-Frobenius-Euler
number.
By letting 1q in the Eq. (1.5), it yields to
1 1,
1
1
lim | : |
1.
2
n q nq
ny
p
H x H x
x y d y
Recently, many mathematicians have studied the
symmetric identities on some special polynomials, see, for
details, [1,6,7,9,12]. Some of mathematicians also
investigated some applications of Frobenius-Euler
numbers and polynomials (or its q-analog) cf.
[3,4,5,13,14,15,16]. Moreover, Frobenius-Euler numbers
at the value λ = 1 in (1.1) are Euler numbers that is
closely related to Bernoulli numbers, Genocchi numbers,
etc. For more information about these polynomials, look
at [1-21] and the references cited therein.
In the present paper, we obtain not only new but also
some interesting identities which are derived from the
fermionic p-adic q-integral over the p-adic numbers field.
The results derived here is written under Sym (5).
2. Symmetric Identities Involving
q-Frobenius-Euler Polynomials
For iw with 1 mod 2iw with 1,2,3,4,5 ,i
by the Eqs. (1.3) and (1.5), we obtain
1 2 3 41 2 3 4 55 4 2 35 4 1 35 4 1 25 3 1 21 2 3 4
1
1 2 3 41 2 3 4 55 4 2 35 4 1 35 4 1 215 3 1 21 2 3 4
0
2lim 1
1
w w w w yw w w w w xw w w w i
tw w w w jw w w w kw w w w hw w w w y q
p
w w w w yw w w w w xw w w w iw w w w jw w w w kNp w w w w hy w w w w y
Ny
e d y
e
t
q
(2.1)
1 151 2 3 4 5
0 0
1 2 3 4 5 1 2 3 4 55 4 2 3 5 4 1 35 4 1 2 5 3 1 2
2lim 1
1
.
Nw pl y w w w w l w y
Nl y
w w w w l w y w w w w w xw w w w i w w w w j tw w w w k w w w w h
qe
Taking
11 1 131 2 4
5 4 2 3 5 4 1 30 0 0 0 5 4 1 2 5 3 1 2
11
2
i j k hww w w
w w w w i w w w w jw w w w k w w w w hi j k h
on the both sides of Eq. (2.1) gives
11 1 131 2 4
5 4 2 3 5 4 1 30 0 0 0 5 4 1 2 5 3 1 2
1 2 3 41 2 3 4 55 4 2 35 4 1 35 4 1 25 3 1 21 2 3 4
1
11
2
i j k hww w w
w w w w i w w w w jw w w w k w w w w hi j k h
w w w w yw w w w w xw w w w i
tw w w w jw w w w kw w w w hw w w w y q
pe d y
1 11 1 1 13 51 2 4
0 0 0 0 0 0
1 2 3 4 5 5 4 2 35 4 1 3 5 4 1 2 5 3 1 2
1 2 3 4 5 1 2 3 4 55 4 2 3 5 4 1 35 4 1 2 5 3 1 2
lim 1
Nw ww w w pi j k h y l
Ni j k h l y
w w w w l w y w w w w iw w w w j w w w w k w w w w h
w w w w l w y w w w w w xw w w w i w w w w jw w w w k w w w w h
e
.
t
q
(2.2)
Note that the equation (2.2) is invariant for any
permutation 5.S Hence, we have the following
theorem.
Theorem 1. Let iw with 1 mod 2iw with
1,2,3,4,5 .i Then the following
1 1 1 11 2 3 4
0 0 0 0
5 4 2 3
5 4 1 3
5 4 1 2
5 3 1 2
1 2 3 4 5
1 2 3 4
1 2 3 4 5
5 4 2 3
5 4
11
2
exp([
w w w w
i j k h
i j k h
w w w w i
w w w w j
w w w w k
w w w w h
w w w w l w y
p
w w w w y
w w w w w x
w w w w i
w w w
1 3
5 4 1 2
15 3 1 2 ] )q
w j
w w w w k
w w w w h t d y
92 Turkish Journal of Analysis and Number Theory
holds true for any 5.S
By Eq. (1.2), we easily derive that
1 2 3 4 1 2 3 4 5 5 4 2 3
5 4 1 3 5 4 1 2 5 3 1 2
55
11 2 3 4
5 5 5
2 3 4 1 2 3 4
.
q
q
w w w wq
w w w w y w w w w w x w w w w i
w w w w j w w w w k w w w w h
wy w x i
ww w w w
w w wj k h
w w w
(2.3)
From Eq. (2.1) and (2.3), we obtain
1 2 3 41 2 3 4 55 4 2 35 4 1 35 4 1 25 3 1 21 2 3 4
1
1 2 3 40
1 2 3 4
55
1
5 5
2 3
5
4 1 2 3 4
w w w w yw w w w w xw w w w i
tw w w w jw w w w kw w w w hw w w w y q
p
n
pn
w w w w y
n
w w w wq
e d y
w w w w
wy w x i
w
w wj k
w w
wh
w
1 ,!
n
p
td y
n
(2.4)
from which, we have
1 2 3 4
1 2 3 4 5
5 4 2 31 2 3 41
5 4 1 3
5 4 1 2
5 3 1 2
1 2 3 4 1 2 3 4,
5 5 5 5 1 2 3 45
1 2 3 4
2
1
| .
0 .
n
w w w w y
p
q
nw w w wq n q
w w w w
w w w w y
w w w w w x
w w w w id y
w w w w j
w w w w k
w w w w h
w w w w H
w w w ww x i j k h
w w w w
n
(2.5)
Thus, by Theorem 1 and (2.5), we procure the
following theorem.
Theorem 2. For iw with 1 mod 2iw with
1,2,3,4,5 ,i the following
1 2 3 4
1 1 1 11 2 3 4
0 0 0 0
5 4 2 3 5 4 1 3
5 4 1 2 5 3 1 2
1
n
q
w w w w
i j k h
i j k h
w w w w i w w w w j
w w w w k w w w w h
w w w w
1 2 3 4,
5 5 5
51 2 3
5 1 2 3 4
4
|
w w w wn q
w w w w
H
w w ww x i j k
w w w
wh
w
holds true for any 5.S
It is shown by using the definition of [ ]qx that
5 5 5 55
1 2 3 4 1 2 3 4
5
1 2 3 40
4 2 3 4 1 3
4 1 2 3 1 2 5
5 4 2 3 5 4 1 35 4 1 2 5 3 1 2
51 2 3 4
.
n
w w w wq
n mn
q
m q
n m
wq
w w w w i w w w w jm
mw w w w k w w w w h
w w w wq
w w w wy w x i j k h
w w w w
wn
m w w w w
w w w i w w w j
w w w k w w w h
q y w x
(2.6)
Taking 1 2 3 41
w w w w y
pd y on the both sides of
Eq.(2.6) gives
55
1
51 2 3 41
2
5 5
3 4 1 2 3 4
5
1 2 3 40
4 2 3 4 1 3 4 1 2 3 1 25
5 4 2 3 5 4 1 3 5 4 1 2 5 3 1 2
1 2
n
w w w w y
p
w w w wq
n mn
q
m q
n m
wq
m w w w w i w w w w j w w w w k w w w w h
w w
wy w x i
w
wj d y
w
w wk h
w w
wn
m w w w w
w w w i w w w j w w w k w w w h
q
3 45 1
1 2 3 4
5
1 2 3 40
4 2 3 4 1 3 4 1 2 3 1 25
5 4 2 3 5 4 1 3 5 4 1 2 5 3 1 2
1 2 3 451 2 3 4,
2
1
| .
mw w yw w w w
qp
n mn
q
m q
n m
wq
m w w w w i w w w w j w w w w k w w w w h
w w w ww w w w
n q
y w x d y
wn
m w w w w
w w w i w w w j w w w k w w w h
q
H w x
(2.7)
By the Eq. (2.7), we have
11 1 131 2 4
1 2 3 40 0 0 0
11
2
ww w wn i j k h
qi j k h
w w w w
Turkish Journal of Analysis and Number Theory 93
5 4 2 3 5 4 1 3 5 4 1 2 5 3 1 2
55
1
51 2 3 41
2
5 5
3 4 1 2 3 4
1 2 3 4 50
1 2 3 451 2 3 4,
13 4
0 0
|
1
w w w w i w w w w j w w w w k w w w w h
n
w w w w y
p
w w w wq
nm n m
q qm
w w w ww w w w
n q
w wi j k h
k h
wy w x i
w
wj d y
w
w wk h
w w
nw w w w w
m
H w x
11 11 2
0 0
5 4 2 3 5 4 1 3 5 4 1 2 5 3 1 2
4 2 3 4 1 3 4 1 2 3 1 2
2 4 3 1 3 4 1 2 4 1 2 35
1 2 3 4 50
1 2 3 451 2 3 4,
15,
|
,
w w
i j
w w w w i w w w w j w w w w k w w w w h
m w w w i w w w j w w w k w w w h
n m
wq
nm n m
q qm
w w w ww w w w
n q
wn q
q
w w w i w w w j w w w k w w w h
nw w w w w
m
H w x
C w
2 3 4, , | ,w w w m(2.8)
where
1 2 3 45,
11 1 131 2 4
0 0 0 0
5 4 2 3 5 4 1 3 5 4 1 2 5 3 1 2
4 2 3 4 1 3 4 1 2 3 1 2
2 4 3 1 3 4 1 2 4 1 2 35
, , , |
1
.
wn q
ww w wi j k h
i j k h
w w w w i w w w w j w w w w k w w w w h
m w w w i w w w j w w w k w w w h
n m
wq
C w w w w m
q
w w w i w w w j w w w k w w w h
(2.9)
Consequently, by (2.9), we get the following theorem.
Theorem 3. Let iw with 1 mod 2iw with
1,2,3,4,5 .i Then the following expression
51 2 3 40
1 2
3 451 2 3 4
,
1 2 3 45,
|
, , , |
n m n m
qqm
w w
w w
w w w wn q
wn q
nw w w w w
m
H w x
C w w w w m
holds true for some 5.S
3. Conclusion
We have derived some new interesting identities of
q-Frobenius-Euler polynomials. We also showed that
these symmetric identities are written by symmetric group
of degree five.
References
[1] E. Ağyüz, M. Acikgoz and S. Araci, A symmetric identity on the
q-Genocchi polynomials of higher order under third Dihedral
group D3, Proc. Jangjeon Math. Soc. 18 (2015), No. 2, pp. 177-
187.
[2] S. Araci, M. Acikgoz, E. Sen, On the extended Kim.s p-adic q-
deformed fermionic integrals in the p-adic integer ring, J. Number
Theory 133 (2013) 3348-3361.
[3] S. Araci, M. Acikgoz, On the von Staudt-Clausen.s theorem
related to q-Frobenius-Euler number, J. Number Theory (2016).
[4] S. Araci and M. Acikgoz, A note on the Frobenius-Euler numbers
and polynomials associated with Bernstein polynomials, Adv.
Stud. Contemp. Math. 22 (2012), No. 3, pp. 399-406.
[5] S. Araci, E. Sen, M. Acikgoz, Theorems on Genocchi
polynomials of higher order arising from Genocchi basis,
Taiwanese J. Math.(2014) Vol. 18, No. 2, pp. 473-482.
[6] D. V. Dolgy, Y. S. Jang, T. Kim, H. I. Kwon, J.-J. Seo, Identities
of symmetry for q-Euler polynomials derived from fermionic
integral onp under symmetry group S3, Applied Mathematical
Sciences, Vol. 8 (2014), no. 113, 5599-5607.
[7] D. V. Dolgy, T. Kim, S.-H. Rim, S.-H. Lee, Some symmetric
identities for h-extension of q-Euler polynomials under third
dihedral group D3, International Journal of Mathematical Analysis
Vol. 8 (2014), no. 48, 2369-2374.
[8] Y. He and S. J. Wang, New formulae of products of the
Frobenius-Euler polynomials, J. Ineq. Appl. (2014), 2014:261.
[9] Y. S. Jang, T. Kim, S.-H. Rim, J.-J. Seo, Symmetry Identities for
the Generalized Higher-Order q-Bernoulli Polynomials under S3,
International J. Math. Anal., Vol. 8 (2014), no. 38, 1873-1879.
[10] T. Kim, q-Volkenborn integration, Russ. J. Math. Phys., 9 (2002),
no. 3, 288-299.
[11] T. Kim, Some identities on the q-Euler polynomials of higher
order and q-Stirling numbers by the fermionic p-adic integral on
p, Russian J. Math. Phys., 16, 484-491 (2009).
[12] T. Kim, q-Euler numbers and polynomials associated with p-adic
q-integrals, Journal of Nonlinear Mathematical Physics 14 (1) 15-
27, (2007).
[13] T. Kim and J. J. Seo, New identities of symmetry for Carlitz.s-
type q-Bernoulli polynomials under symmetric group of degree
five, International Journal of Mathematical Analysis Vol. 9, 2015,
no. 35, 1707-1713.
[14] T. Kim and J. J. Seo, Some identities of symmetry for Carlitz-type
q-Euler polynomials invariant under symmetric group of degree
five, International Journal of Mathematical Analysis Vol. 9, 2015,
no. 37, 1815-1822.
[15] T. Kim, Some New identities of symmetry for higher-order Carlitz
q-Bernoulli polynomials arising from p-adic q-integral on p
under the symmetric group of degree five, Applied Mathematical
Sciences, Vol. 9, 2015, no. 93, 4627-4634.
[16] D. S. Kim and T. Kim, Some identities of symmetry for Carlitz q-
Bernoulli polynomials invariant under S4, Ars Combinatoria, Vol.
CXXIII, pp. 283-289, 2015.
[17] D. S. Kim and T. Kim, Some new identities of Frobenius-Euler
numbers and polynomials, J. Ineq. Appl. (2012), 2012:307.
[18] Y. Simsek, Generating functions for q-Apostol type Frobenius-
Euler numbers and polynomials, Axioms (2012), 1, 395-403.
[19] H. M. Srivastava, Some formulas for the Bernoulli and Euler
polynomials at rational arguments, Math. Proc. Camb. Philos. Soc.
129, 77-84 (2000)
[20] H. M. Srivastava, Some generalizations and basic (or q-)
extensions of the Bernoulli, Euler and Genocchi polynomials,
Appl. Math. Inform. Sci. 5, 390-444 (2011).
[21] B. Y. Yasar and M. A. Özarslan, Frobenius-Euler and Frobenius-
Genocchi polynomials and their di¤ erential equations, NTMSCI 3
(2015), No. 2, 172-180.