Operator (less than sign) cannot be used with a left hand side of type boolean and a right hand side of type float

HI, I know that similar question have been asked many times on these forums but my instance of this is really confusing me, I have a relatively simple script where I declare a set of variables at the beginning, defining them all as float variables but when I try and compare them in an if statement, it gives me the error in the title and indicates that one of the variables is a boolean.

the errors points to (18,34), (27,34), (36,34), (45,34), (54,34) and (63,34)

 #pragma strict
  var acceleration : float = 1.5;
  var top_speed : float = 1.5;
  var speed_x : float = 0.0;
  var speed_y : float = 0.0;
  var speed_z : float = 0.0;
 
 
 function Start () {
 
 }
  
  function Update () {
      speed_x = speed_x - (top_speed / 2*(acceleration));
      
     if(Input.GetKey(KeyCode.RightArrow))
     {
         if (-top_speed < speed_x < top_speed)
         {
             speed_x = speed_x + (top_speed / acceleration);
         }
     }
 
 
     if(Input.GetKey(KeyCode.LeftArrow))
     {
         if (-top_speed < speed_x < top_speed)
         {
             speed_x = speed_x - (top_speed / acceleration);
         }
     }
 
 
     if(Input.GetKey(KeyCode.DownArrow))
     {
         if (-top_speed < speed_y < top_speed)
         {
             speed_y = speed_y - (top_speed / acceleration);
         }
     }
 
 
     if(Input.GetKey(KeyCode.UpArrow))
     {
         if (-top_speed < speed_y < top_speed)
         {
             speed_y = speed_y + (top_speed / acceleration);
         }
     }
 
 
     if(Input.GetKey(KeyCode.Space))
     {
         if (-top_speed < speed_z < top_speed)
         {
             speed_z = speed_z + (top_speed / acceleration);
         }
     }
 
 
     if(Input.GetKey(KeyCode.LeftControl))
     {
         if (-top_speed < speed_z < top_speed)
         {
             speed_z = speed_z - (top_speed / acceleration);
         }
     }
 
 
 
     transform.Translate(new Vector3(speed_x * Time.deltaTime, speed_y * Time.deltaTime, speed_z * Time.deltaTime));
  }