s:a = x0 < x1 < x2 < < xn = b [a,b], d(s) = max Dxi, Dxi = xi xi-1 (i = 1, 2, , n),
f(x) Î R[a,b].
.
, a
,
:
1) s (. . ) S (s) , `S(s) .
2) S (s1) ` S(s2).
3)
, .
, .
[a, b] f(x)
,
. Þ f(x) Î R[a,b] , S(s, x) I,"e > 0 $d > 0 "s,
d(s) < d: | S(s, x) - I | < e/3. x, : "e > 0 $d > 0 "s, d(s) < d: | S (s) - I | £ e/3, | `S(s) I | £ e/3, | `S(s) - S (s) | £ 2e/3 < e.
Ü ` S(s) - S (s) 0, S (s) £ I £ `I £ `S(s), S (s) £ S(s, x)£`S(s),
S(s, x) I = I = `I #
: 1) ,
2) ,
3) .
2.
) sups infx S(s, x) = infs supx S(s, x),
) lim S(sn, x) n¥
s1 Ì s2 Ì s3 Ì...
d(sn) 0 x,
) lim S (sn) = lim`S(sn)
s1 Ì s2 Ì s3 Ì... d(sn) 0,
) lim [S(s, x) - S(s, x)] = 0
max{d(s), d(s)} 0 x x
) "e > 0 $s, s: `S(s) - S (s) < e
3. .
, a > 0 , ³ a,
. .
Þ .
Ü .
a < e/2(b-a), d ,
|
|
W = w(f, [a, b]) f(x) [a, b].
: 1) ,
2) ,
3) .
4. .
(
)
1) ( ) ; ( ),
2) D < a,
$ d > 0 , " D¢Ì D < d
< a.
. 1) . 2) . x [a, b] w(f, x) < a, "d > 0 $ [a¢, b]Ì [a, b] b' - a' < d, w(f, [a, b]) ³ a. [an, bn] [a, b] , bn - an 0, w(f, [an, bn]) ³ a. an, a £ an £ b an , a £ an £ b, x, a £ x £ b, bn - an 0. x ( [a, b]) [an , bn], w(f, [an , bn]) ³ a. w(f, x) ³ a (?!).
-
a = { x Î [a, b] , w(f, x) ³ a }
, a > 0 Ea f(x), ³ a, ,
. -.
Þ .
Ü -. pg(Ea) = 0,
, , ( (a, b) (a, b) (min{a,a}, max{b, b})). D1 , D2 , - ; +1, w(f, x) < a. , 2) , Dj dj d dj (j=1, 2, 3, , k+1). s d(s) < d [xi-1, xi] , w(f, [xi-1, xi]) ³ a, Dj . :
d(s) < d, (ai, bi) e/2, d = min{d, e/4k}. #
|
|
: 1) ,
2) ,
3) .
5. - - .
= { x Î [a, b] , w(f, x) > 0 }
, ,
. - .
Þ -, a > 0 Ea f(x), ³ a, . ,
n E1/n e/2n. n ÎN , ( ) E e/2 + e/4 +e/8 +...= e.
Ü . E f(x), a Ì a > 0 . , a a > 0 , ( ) . a , a Ì [a, b]. a . , , (a) Ì a. x Î (a). a xn , xn x. Ux x xn, , w(f,Ux) ³ w(f, xn) ³ a. w(f, x) = inf w(f,Ux) ³ a, x Î a. #
: 1) ,
2) ,
3) .
( ):
1) ,
,
2)
. , , . , [a, b] Ç Q
, ,
3)
,
4)
,
.
6. .
7. ,
,
.
14.
a(x): 1(x) + 2(x) + + n(x) + ,
, . ,
a(x): 0 + 1 (x x0) + + n (x x0)n +
a(x): 0 /2 + (1 sin x + b1 cos x) + + (an sin nx + bn cos nx) +
(x) x, n(x) , (x) .
, , :
1) S(x) (x),
|
|
n(x) Sn(x)?
, , Sn(x)
() S(x)?
2) ( , , )?
3) ? . .
XIX , S(x) an(x) = an (x - x0)n Sn(x) . : 1826 . , S(x)
sin x (sin 2x)/2 + (sin 3x)/3 + + (-1)n+1(sin nx)/n +
x = (2k + 1) , k Z. . .
a(x) an(x), A ( A), x A S(x),
S(x) A ( A)
| S(x) S(x0)| | S(x) Sn(x)| + | Sn(x) Sn(x0)| + | Sn(x0) S(x0)|
Sn(x0) S(x0), n < . n < Sn(x) x0:
, , | (x)| = |S(x) - Sn(x)|. = sup| (x)| ( x A). , 0 , < n.
(*)
, (1841 .) ( , 1 - ) a(x) . ,
A1 c:
A1 c ( ) a(x) x A (+ Sn(x) Sn(x) ).
+ : 1) ,
2) ,
3)
A1 c- a(x) A :
a(x) A1 A Û
(**)
, a(x) A1 A,
, (**), n m = n + p ,
,
A1 a(x) A.
, , a(x) A ,
a(x) , A : , x A n N
.
13. ,
|
|
( ).
( ).
a(x) an(x), A ( A), () x A S(x). , S(x) , , a(x) 3 - ( ) S(x) , B3 c:
.
a(x) 3 S(x) . , S(x) . x0 A > 0 > 0 , |x x0| < | S(x) S(x0)| < . Sn(x0) S(x0) n ,
a(x) 3 - S(x) ,
, Sn(x) x0
|x x0| < = min{ , } ,
| S(x) S(x0)| £ | S(x) Sn(x)| + | Sn(x) Sn(x0)| + | Sn(x0) S(x0)| <
S(x) , a(x) S(x) . , a(x) 3 S(x) . , n n(x) = S(x) - Sn(x) .
n0 - . n (x0) 0 n ,
n > 0 :
,
, a(x) 3 S(x) . #
.
1) , a(x) an(x), A ( A), () x Î A S(x), , S(x) x0 ( A),
,
2) ., ,
. . II.
// , - , 1996, . 7-12.
+ :
14. N(x, ) = { n , | Sn(x) S(x)| < }. :
1) a(x) S(x) ,
N(x, ) ,
n0 ,
2) 1 - a(x) S(x) ,
N(x, ) x A
, n0 ,
3) 3 - a(x) S(x) ,
N [1, n1],
[n1 + 1, n2], , N(x, ) .
. a(x)
S(x) , a(x)
S(x) .
. , , , , (x) (, n(x) 0), 3 1 . , |Sn(x) S(x)| n , 3 ,
|x x0| < , x0 A, = (, x0) . , .
n n0 = max {n1, n2, , nm} ( nk xk) : |Sn(x) S(x)| < e, 1 a(x) S(x).
.
1) 1 Sn(x) S(x)
: Sn(x) S(x)
2) (x)
( Sn(x)) S(x) , (x)
( Sn(x)
S(x)), :
Sn(x) S(x) S(x)
: 1 1 + 1 1 + + (-1)n+1 +
b: sin1 + sin2 + + sin n +
c: 1 + 2 + 4 + 8 + 16 + + 2n-1 +
( n ). , :
|
|
1) ();
2) , ,
();
3) ().
, :
a: 1 + 2 + + n + , - Sn. = (S1 + S2 + + Sn)/n a; S = lim Sn a
a: 0 + 1 + 2 + + n + , a(): 0 + 1 + 2 2 + + n n +
1; S = lim Sn() 1 - 0 - a
a(x): 0 + 1 (x x0) + 2 (x x0)2 + + n (x x0)n + , S(), 0, (**); S() a
+ , ( )
17. ) b .
) ,
.
S ,
1) S,
2) A S B S, A B S,
3) A S, A1 S A1 A, A
A = A1 + A2 + A3 + + Ak , Ai S.
S S,
A S: A E A
S , S. , S , , S, S.
R , , ,
A R B R, A B R, A B R, A - B R.
, = A - A R, A R, A1 R A1 A, A A = A1 + A2 , A2 = A A1 R.
R A D B = (A - B) + ( - ). , , , , , , .
R M.
R , S R(S), , S. R(S), S, , S. R(S), S, , S, R S,
A R(S) A = A1 + A2 + + Ak, Ai S
R - , , Ai (i = 1, 2, 3, ) R, R.
- R - . ,
- M, . M - - , ,
- R - , S R(S), s - , S. - R(S), S, - , S. - R(S), S, , S,
- R(S) S,
A R(S) A = A1 + A2 + + Ak + , Ai S
+ :
1) - ,
2) - ,
3) - c ,
4) - ,
5) - ,
1') - ,
2') - ,
3') - c ,
4') - ,
5') - ,
6) S ,
7) S - ,
S = { , A1, A2, , An, }
, - pg R(S) - ( - ) :
1) pg S , , R(S),
- M(S)
, , :
2) - M(S)
, -
M = {A E} = E ,
- .
S R(S) A E *(A) A E Ai S.
, A E ( ),
+ :