scheme 
iplane =
class
  type
   Time=Nat><Nat,
   Place=Text,	
   Status=Text,
   PlaneInfo=Time><Nat><Place><Time><Status,
   Table=PlaneInfo-list
      	
value
     CreateTable : Table =<..>,
     IsInTable: Nat><Table->Bool,
     less:Time><Time->Bool, 
     AddPlane:PlaneInfo><Table->Table,
     DeletePlane:Nat><Table->Table,
     ChangeTime:Table><Nat><Time -> Table,
     ChangeStatus:Table><Nat><Status -> Table,
     GetPlanes: Place><Table->Table

axiom
   
/*++*/ /*IsInTable*/
     all num:Nat :- 
       IsInTable(num,CreateTable) is false,
     all (a,b,c,d,e): PlaneInfo ,time1 : Time, status1:Status ,tab:Table , num:Nat :-  
      IsInTable(num,AddPlane((a,b,c,d,e),CreateTable)) is
        if (b=num) 
         then true
         else
          false
         end,       
     all (a,b,c,d,e): PlaneInfo ,time1: Time, status1:Status ,tab:Table , num:Nat :-   
      IsInTable(num,AddPlane((a,b,c,time1,status1),tab)) is        
         if num=b then  true 
          else   
           IsInTable(num,tab)  
          end,
    /* Is it wrong or not */      
    /* all tab:Table,num:Nat :-     
        IsInTable(num,tab) is
          if tab=<..> then false else
          let (a,b,c,d,e)=(hd tab) in 
           if(b=num)
             then true
             else
              IsInTable(num ,tl tab)           
           end
          end end ,*/
/*++*//* less */   
     all (h1,m1):Time,(h2,m2) : Time :-
        less((h1,m1),(h2,m2)) is 
          if (h1<h2) then true 
            else 
              if h1=h2 then m1 < m2
               else false
              end 
           end ,
           
   /*AddPlane*/     
   all (a,b,c,d,e): PlaneInfo ,tab:Table , num:Nat :-   
    DeletePlane(num,AddPlane((a,b,c,d,e),tab)) is 
     if b=num 
       then
        tab
       else
        DeletePlane(num,tab)
       end
       
       
         
          




end