Inequalities for exponentials in Banach algebras
    
    
  
  
  
      
      
      
        
Studia Mathematica, Tome 100 (1991) no. 1, pp. 87-94
    
  
  
  
  
  
    
      
      
        
      
      
      
    Voir la notice de l'article provenant de la source Institute of Mathematics Polish Academy of Sciences
            
              For commuting elements x, y of a unital Banach algebra ℬ it is clear that $∥e^{x+y}∥ ≤ ∥e^x∥ ∥e^y∥$. On the order hand, M. Taylor has shown that this inequality remains valid for a self-adjoint operator x and a skew-adjoint operator y, without the assumption that they commute. In this paper we obtain similar inequalities under conditions that lie between these extremes. The inequalities are used to deduce growth estimates of the form $∥e'^{}∥ ≤ c(1 + |ξ|〉^s$ for all $ξ ∈ R^m$, where $x = (x_1,..., x_m) ∈ ℬ^m$ and c, s are constants.
            
            
            
          
        
      @article{10_4064_sm_100_1_87_94,
     author = {A. J. Pryde},
     title = {Inequalities for exponentials in {Banach} algebras},
     journal = {Studia Mathematica},
     pages = {87--94},
     publisher = {mathdoc},
     volume = {100},
     number = {1},
     year = {1991},
     doi = {10.4064/sm-100-1-87-94},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-100-1-87-94/}
}
                      
                      
                    A. J. Pryde. Inequalities for exponentials in Banach algebras. Studia Mathematica, Tome 100 (1991) no. 1, pp. 87-94. doi: 10.4064/sm-100-1-87-94
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