Unitary Signings and Induced Subgraphs of Cayley Graphs of
  $\mathbb{Z}_2^{n}$
    
    
  
  
  
      
      
      
        
Advances in Combinatronics (2020)
    
  
  
  
  
  
    
      
      
        
      
      
      
    Voir la notice de l'article provenant de la source Advances in Combinatronics website
            
              Let $G$ be a Cayley graph of the elementary abelian $2$-group
$\mathbb{Z}_2^{n}$ with respect to a set $S$ of size $d$. We prove that for any
such $G, S$ and $d$, the maximum degree of any induced subgraph of $G$ on any
set of more than half the vertices is at least $\sqrt d$. This is deduced from
the recent breakthrough result of Huang who proved the above for the
$n$-hypercube $Q^n$, in which the set of generators $S$ is the set of all
vectors of Hamming weight $1$. Motivated by his method we define and study
unitary signings of adjacency matrices of graphs, and compare them to the
orthogonal signings of Huang. As a byproduct, we answer a recent question of
Belardo et. al. about the spectrum of signed $5$-regular graphs.
            
            
            
          
        
      
                
                  
                  
                    
                    
                  
                    
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              @article{ADVC_2020_a0,
     author = {Noga Alon and Kai Zheng},
     title = {Unitary {Signings} and {Induced} {Subgraphs} of {Cayley} {Graphs} of
  $\mathbb{Z}_2^{n}$},
     journal = {Advances in Combinatronics},
     publisher = {mathdoc},
     year = {2020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ADVC_2020_a0/}
}
                      
                      
                    Noga Alon; Kai Zheng. Unitary Signings and Induced Subgraphs of Cayley Graphs of
  $\mathbb{Z}_2^{n}$. Advances in Combinatronics (2020). http://geodesic.mathdoc.fr/item/ADVC_2020_a0/