1939 no relation combinatorics
Solution of Heffter's Difference Problems
Peltesohn solved the Difference Problems of Lothar Heffter (1896) in combinatorics in 1939. A Difference Triple (a, b, c) is defined as three different elements from the set 
  
    
      
        1
        ,
        2
        ,
        …
        ,
        v
        −
        1
      
    
    {\displaystyle 1,2,\dots ,v-1}
  , whose sum 
  
    
      
        
          mod
          
            v
          
        
      
    
    {\displaystyle {\bmod {v}}}
   equals zero (
  
    
      
        a
        +
        b
        +
        c
        =
        0
        
          mod
          
            v
          
        
      
    
    {\displaystyle a+b+c=0{\bmod {v}}}
  ) or for which one element 
  
    
      
        
          mod
          
            v
          
        
      
    
    {\displaystyle {\bmod {v}}}
   equals the sum of the other two (
  
    
      
        a
        +
        b
        =
        c
        
          mod
          
            v
          
        
      
    
    {\displaystyle a+b=c{\bmod {v}}}
  ).
no relation