Jordan Triple Product Homomorphisms on Triangular Matrices to and from Dimension One

2018 ◽  
Vol 33 ◽  
pp. 147-159
Author(s):  
Damjana Kokol Bukovsek ◽  
Blaz Mojskerc

A map $\Phi$ is a Jordan triple product (JTP for short) homomorphism whenever $\Phi(A B A)= \Phi(A) \Phi(B) \Phi(A)$ for all $A,B$. We study JTP homomorphisms on the set of upper triangular matrices $\mathcal{T}_n(\mathbb{F})$, where $\Ff$ is the field of real or complex numbers. We characterize JTP homomorphisms $\Phi: \mathcal{T}_n(\mathbb{C}) \to \mathbb{C}$ and JTP homomorphisms $\Phi: \mathbb{F} \to \mathcal{T}_n(\mathbb{F})$. In the latter case we consider continuous maps and the implications of omitting the assumption of continuity.

2006 ◽  
Vol 183 (2) ◽  
pp. 729-737 ◽  
Author(s):  
Rafael Álvarez ◽  
Francisco Ferrández ◽  
José-Francisco Vicent ◽  
Antonio Zamora

1995 ◽  
Vol 118 (1) ◽  
pp. 183-188
Author(s):  
Qi Zhang

Let X be a smooth projective variety of dimension n over the field of complex numbers. We denote by Kx the canonical bundle of X. By Mori's theory, if Kx is not numerically effective (i.e. if there exists a curve on X which has negative intersection number with Kx), then there exists an extremal ray ℝ+[C] on X and an elementary contraction fR: X → Y associated with ℝ+[C].fR is called a small contraction if it is bi-rational and an isomorphism in co-dimension one.


2019 ◽  
Vol 26 (1/2) ◽  
pp. 197-201
Author(s):  
Driss Aiat Hadj Ahmed

Let ℱ be a field of zero characteristic, let Nn(ℱ) denote the algebra of n×n strictly upper triangular matrices with entries in ℱ, and let f:Nn(ℱ)→Nn(ℱ) be a nonlinear Jordan centralizer of Nn(ℱ),that is, a map satisfying that f(XY+YX)=Xf(Y)+f(Y)X, for all X, Y∈Nn(ℱ). We prove that f(X)=λX+η(X) where λ∈ℱ and η is a map from Nn(ℱ) into its center 𝒵(Nn(ℱ)) satisfying that η(XY+YX)=0 for every X,Yin Nn(F).


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