Complexity of Index Sets for Several Classes of Models
    
    
  
  
  
      
      
      
        
Sibirskij žurnal čistoj i prikladnoj matematiki, Tome 8 (2008) no. 1, pp. 71-76
    
  
  
  
  
  
    
      
      
        
      
      
      
    Voir la notice de l'article provenant de la source Math-Net.Ru
            
              			When we study questions about computable characterization existence for different classes of models the approach suggested by Goncharov and Knight [1] is effective. It consists of obtaining precise estimations of index sets of such classes in corresponding hierarchy. 
For the universal numeration of computable models in non-trivial computable language there were found precise estimations of the following index sets of computable models classes: models with Ehrenfeucht theory ($\Pi^1_1$), models with a theory admitting infinitely many countable models ($\Sigma^1_1$).
			
            
            
            
          
        
      @article{VNGU_2008_8_1_a6,
     author = {E. N. Pavlovsky},
     title = {Complexity of {Index} {Sets} for {Several} {Classes} of {Models}},
     journal = {Sibirskij \v{z}urnal \v{c}istoj i prikladnoj matematiki},
     pages = {71--76},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {2008},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VNGU_2008_8_1_a6/}
}
                      
                      
                    E. N. Pavlovsky. Complexity of Index Sets for Several Classes of Models. Sibirskij žurnal čistoj i prikladnoj matematiki, Tome 8 (2008) no. 1, pp. 71-76. http://geodesic.mathdoc.fr/item/VNGU_2008_8_1_a6/
