scholarly journals An additive functional inequality in matrix normed spaces

2013 ◽  
pp. 1009-1022
Author(s):  
Choonkil Park ◽  
Dong Yun Shin ◽  
Jung Rye Lee
Filomat ◽  
2014 ◽  
Vol 28 (4) ◽  
pp. 677-694 ◽  
Author(s):  
R. Saadati ◽  
Gh. Sadeghi ◽  
Th.M. Rassias

In this paper, we approximate the following additive functional inequality ?( ?d+1,i=1 f(x1i),..., ?d+1,i=1, f(xki))? ? ?mf (?d+1,i=1 x1i/m),..., mf (?d+1,i=1 xki/m)) ?k for all x11,..., xkd+1?X. We investigate homomorphisms in proper multi-CQ*-algebras and derivations on proper multi-CQ*-algebras associated with the above additive functional inequality.


Filomat ◽  
2016 ◽  
Vol 30 (7) ◽  
pp. 1691-1696
Author(s):  
Yeol Cho ◽  
Reza Saadati ◽  
Young-Oh Yang ◽  
H.M. Kenari

In this paper, we apply fixed point technique to investigate the following additive functional inequality: ||f(x)+f(y)+f(z)+f(w)||?||f(x+y)+f(z+w)|| in normed modules over a C*-algebra, which is also applied to understand homomorphisms in C*-algebras. Our results improve and generalize some results given by some authors. Especially, we get a better error estimation of An?s main result.


2014 ◽  
Vol 22 (2) ◽  
pp. 317-323
Author(s):  
Sung Jin Lee ◽  
Choonkil Park ◽  
Dong Yun Shin

2013 ◽  
Vol 59 (2) ◽  
pp. 299-320
Author(s):  
M. Eshaghi Gordji ◽  
Y.J. Cho ◽  
H. Khodaei ◽  
M. Ghanifard

Abstract In this paper, we investigate the general solution and the generalized stability for the quartic, cubic and additive functional equation (briefly, QCA-functional equation) for any k∈ℤ-{0,±1} in Menger probabilistic normed spaces.


2011 ◽  
Vol 2011 ◽  
pp. 1-19 ◽  
Author(s):  
M. Janfada ◽  
R. Shourvazi

We study general solutions and generalized Hyers-Ulam-Rassias stability of the following -dimensional functional equation , , on non-Archimedean normed spaces.


Filomat ◽  
2016 ◽  
Vol 30 (7) ◽  
pp. 1651-1658
Author(s):  
Choonkil Park

In this paper, we solve the following additive ?-functional inequalities ||f (x + y) - f (x) - f (y)|| ? ???(2f (x+y/2) - f(x) + -f (y))??, (1) where ? is a fixed complex number with |?|<1, and ??2f(x+y/2)-f(x)- f(y)???||?(f(x+y)-f(x)-f(y))||, (2) where ? is a fixed complex number with |?|<1/2 , and prove the Hyers-Ulam stability of the additive ?-functional inequalities (1) and (2) in ?-homogeneous complex Banach spaces and prove the Hyers-Ulam stability of additive ?-functional equations associated with the additive ?-functional inequalities (1) and (2) in ?-homogeneous complex Banach spaces.


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