我可以使用set而不是某些关键字

Question

如何在下面的谓词中编写'set'而不是'some'关键字

pred foreward [rov: Robot, d: Direction, t,t': Time] {
-- preconditions  
   -- rover is on
   is_on[rov, t]

   -- d is rover's direction
   rov.dir.t = d
   let np = next_pos[rov.pos.t, d] | {
     -- precondition
     some np              //<-------------   here changes are needed
     --postcondition
     rov.pos.t' = np
   }

-- frame conditions
   -- all rovers stay on or off as they were
   no_on_changes[Robot, t, t']
  -- No rover changes direction  
   no_direction_changes[Robot, t, t']
   -- No other rover changes position
   no_position_changes[Robot - rov, t, t']
}

Answer 1

如果你的意思是# np >= 0，那么这总是正确的，因为你不能有负数的np＆＃39;