650                                                     20

     ,   . 20.3,  $5,  -
      :

. =  {-$5, ^ - $100 - $5} =
' =max{-$5, ^-$105} .

^ = max {-$5, $100 - , - $5} =
= max {-$5, $95 - .,} .

        , -
     $5,       $100, 
         $105.  ,
      ,      
  $105.  ,  $105,   -
  . (,   $108   $3,   -
      $5    $100,  
,   $108).

,          
,     $100,       $95.  
    .    -
   ,         $5.  -
,          ,    
     $95.      -
  $95    . (,   $92 
 $3,       $5    
 $100,   $92.)

 . 20.4 ()  ()      ()  ().
      ,      
 , ,     $108,     -
   $3,         $3 (
   $5  $100    ,    
  $108). ,      $3, 
    $3.

20.5.3       
  

 ()  () . 20.4     , 
  (straddle).    ( )  -
         ,     
    8.    ,   ()  -
,    ,    ()  (),  . ()
 ,    ,   . ()  (). 
,   ()  ()     , 
 ,        .

 . 20.4 ()     ,   -
 ,     ( $100)     , 
     ,      
.  ,       , 
    9. ,  . 20.4 () -
    ,     
         .

 . 20.4 ()    ,    
     .    ,