!"
!
!
!
#


→ %
$
$
%!
"&'
$$
$
!

→ 
→ (
)
!
$
!*
!
$((
$
$
"
(
"
!
+
"
+*+
$
$
*!(!
!
!
++
!
$
= ∑ =
*
$
(!"
*
!! !
!*
,-
!
!
> +
*
(
$
*!!*
./-
!
!
$
0"&1
$
23
$
(
$
!43
!
!!
$
!
> !
≠
*
!
"&
> %5.++ 61
7-
!
+
$
!
! $
!
!
(
&8
!
!
7
***
(
$(
!
$
!
(
(
"
"
!
(
0
!
&
"
!(
(
(
!
(
!
1
!
(
"
(
(
(!
(!
1
"
!!(
(
!
"
!(
(
*
"
!
1
!
(
!
!
$
!
!(
(
$
!
!
!
!
(
(
$
/
.&9
!
9
!
!0"+&
0"+&
$
:
 ∂ 

  ∂ 
∇ =   =  
∂

  
 ∂ 
!
"
!
! ! 0"+&
$
;
[
∇ = ∇ = + ]
"
!
!!0"+&
! ∇
$
∇ ≈ + $

α = −   $



)
"
-!!
!!
< !!
= + + − + + = + + − + + "&
0
&
0& 1
(
(
0& (
(
(
0&
73$3
&/
∂ ∂ +
∂ ∂ !
∇ =
!
!! !
$
∇ = − + + + $
!!(
$
!!
(
$
!!!1
$
/
!
$
((
$
$
$
!
!
*
"
!
!
;
!/
!
!
$
!1$
$
(!
*/
!.$-9
!!!
 + =  −
σ 
*
$



σ (
/
!
 −σ ∇ = 
 σ

   −

 σ



*
= + = ±σ
$
1
$
/
( * ( 0 ∇ ( 1 +
(+ (+ 1 &
"&
!
!
7
$
$
!
*
*
=
$
!
*
$
(
"
!
$
1 ! + !
!+
!!0&
$
!*
./
,
!
1
!"
0"3"3&
$
!
+!
!"*
*
&!!
.&!
$
∇ − ∇ ′ ′ ≤ $
∇α − ∇α ′ ′ < $
!
!
*
$
!
!(
!
$
"&
!!
(
!"
..9
,(
6
!
!
!
$
*
(!!
$
!
*"
(
66
!
$
$
!
$
$
0
&
= + = − + !
!"
$
= − + $
′ ′
* ′ +
$
′ "
"
!
(
"
+*
(
*
"
+5>0
"
!(
= &
!
!
*((
"
→(
= − + !
!
→
"
?!!
*(
"
= + (
!;
;"
"
$
!(
"
!(
+
!
= + $
!
"
θ + θ = ρ
"
(
"
!
θ = ± ο +
*"
"
1
θ = ο +* ρ = "
(
θ = ο +* ρ = "&
ρθ θ = − ο +* ρ = $
!
*
= (!
(!!!
"&
"
− + − = $-