@prefix : <#> .
     @prefix day: <daysoftheweek.n3#> .
     @prefix log: <http://www.w3.org/2000/10/swap/log#> .
     @prefix math: <http://www.w3.org/2000/10/swap/math#> .
    
    @forAll :x,
                :xl,
                :y,
                :yl .
    
    "Friday"     :follows "Thursday" .
    
    "Monday"     :follows "Sunday" .
    
    "Saturday"     :follows "Friday" .
    
    "Thursday"     :follows "Wednesday" .
    
    "Tuesday"     :follows "Monday" .
    
    "Wednesday"     :follows "Tuesday" .
    {
        
          ( :x 
            "1"  )
             math:sum  [
                 math:equalTo :y ] .
        :x     day:label :xl .
        :y     day:label :yl .
        
        }     log:implies {:yl     :follows :xl .
        } .