ɱɬɨ ɡɧɚɱɟɧɢɹ ɩɚɪɚɦɟɬɪɨɜ, ɩɪɢ ɤɨɬɨɪɵɯ ɢɦɟɸɬ ɦɟɫɬɨ ɬɚɤɢɟ ɤɚɱɟɫɬɜɟɧɧɵɟ ɢɡɦɟɧɟɧɢɹ,
ɧɚɡɵɜɚɸɬɫɹ ɛɢɮɭɪɤɚɰɢɨɧɧɵɦɢ. Ⱦɥɹ ɩɨɥɧɨɝɨ ɩɨɧɢɦɚɧɢɹ ɩɨɜɟɞɟɧɢɹ ɫɢɫɬɟɦɵ ɡɧɚɧɢɟ
ɟɟ ɛɢɮɭɪɤɚɰɢɨɧɧɵɯ ɩɚɪɚɦɟɬɪɨɜ ɚɛɫɨɥɸɬɧɨ ɧɟɨɛɯɨɞɢɦɨ. Ɋɚɫɫɦɨɬɪɢɦ ɫɥɟɞɭɸɳɟɟ
ɷɜɨɥɸɰɢɨɧɧɨɟ ɭɪɚɜɧɟɧɢɟ:
ɝɞɟ ɯ ɨɩɪɟɞɟɥɟɧɨ ɜ ɧɟɤɨɬɨɪɨɦ ɩɪɨɫɬɪɚɧɫɬɜɟ, r ɩɪɟɞɫɬɚɜɥɹɟɬ ɫɨɛɨɣ ɜɟɤɬɨɪ
ɩɚɪɚɦɟɬɪɨɜ, ɚ f — ɜɟɤɬɨɪ-ɮɭɧɤɰɢɹ, ɭɞɨɜɥɟɬɜɨɪɹɸɳɚɹ ɨɩɪɟɞɟɥɟɧɧɵɦ ɬɪɟɛɨɜɚɧɢɹɦ.
ɍ ɧɟɝɨ ɦɨɝɭɬ ɛɵɬɶ ɪɟɲɟɧɢɹ ɪɚɡɥɢɱɧɵɯ ɬɢɩɨɜ — (I) ɩɨɫɬɨɹɧɧɵɟ, (II) ɩɟɪɢɨɞɢɱɟɫɤɢɟ,
(III)
ɫɭɛɝɚɪɦɨɧɢɱɟɫɤɢɟ, (IV) ɚɫɢɦɩɬɨɬɢɱɟɫɤɢ ɤɜɚɡɢɩɟɪɢɨɞɢɱɟɫɤɢɟ ɢ ɬ.ɩ.
Ɋɚɫɫɦɨɬɪɢɦ ɫɥɭɱɚɣ ɪɚɜɧɨɜɟɫɢɹ f(x,r) = 0. ȿɫɥɢ ɨɫɨɛɨ ɧɟ ɨɝɨɜɨɪɟɧɨ, ɞɚɥɟɟ ɜɫɟɝɞɚ
ɛɭɞɟɦ ɩɪɟɞɩɨɥɚɝɚɬɶ, ɱɬɨ f ɞɢɮɮɟɪɟɧɰɢɪɭɟɦɚ ɫɬɨɥɶɤɨ ɪɚɡ, ɫɤɨɥɶɤɨ ɷɬɨ ɧɟɨɛɯɨɞɢɦɨ.
ɉɨɥɨɠɟɧɢɟ ɪɚɜɧɨɜɟɫɢɹ ɦɵ ɦɨɠɟɦ ɪɚɫɫɦɚɬɪɢɜɚɬɶ ɤɚɤ ɮɭɧɤɰɢɸ ɩɚɪɚɦɟɬɪɨɜ. ɉɪɢ
ɡɚɞɚɧɧɨɦ ɧɚɛɨɪɟ ɩɚɪɚɦɟɬɪɨɜ ɭɪɚɜɧɟɧɢɟ ɱɚɫɬɨ ɦɨɠɟɬ ɢɦɟɬɶ ɧɟ ɨɞɧɨ, ɚ ɧɟɫɤɨɥɶɤɨ
ɩɨɥɨɠɟɧɢɣ ɪɚɜɧɨɜɟɫɢɹ, ɢ ɨɫɧɨɜɧɨɣ ɜɨɩɪɨɫ, ɤɨɬɨɪɵɣ ɦɵ ɡɞɟɫɶ ɧɚɦɟɪɟɧɵ ɨɛɫɭɞɢɬɶ,
ɫɨɫɬɨɢɬ ɜ ɬɨɦ, ɤɚɤ ɪɚɜɧɨɜɟɫɢɟ ɡɚɜɢɫɢɬ ɨɬ ɩɚɪɚɦɟɬɪɨɜ ɡɚɞɚɱɢ.
ɉɭɫɬɶ ɞɥɹ ɭɞɨɛɫɬɜɚ x ɢ r ɩɪɢɧɚɞɥɟɠɚɬ R
1
. Ȼɢɮɭɪɤɚɰɢɨɧɧɚɹ (ɫɬɚɬɢɱɟɫɤɚɹ) ɡɚɞɚɱɚ
ɷɤɜɢɜɚɥɟɧɬɧɚ ɢɫɫɥɟɞɨɜɚɧɢɸ ɤɪɢɜɵɯ f(x,r) = 0 ɢ ɢɯ ɨɫɨɛɵɯ ɬɨɱɟɤ. Ɉɫɧɨɜɧɵɦ
ɢɧɫɬɪɭɦɟɧɬɨɦ ɞɨɤɚɡɚɬɟɥɶɫɬɜɚ ɫɭɳɟɫɬɜɨɜɚɧɢɹ ɪɟɲɟɧɢɣ ɜ ɬɟɨɪɢɢ ɛɢɮɭɪɤɚɰɢɣ
ɹɜɥɹɟɬɫɹ ɬɟɨɪɟɦɚ ɨ ɧɟɹɜɧɨɣ ɮɭɧɤɰɢɢ ɞɥɹ ɜɟɤɬɨɪɧɨɡɧɚɱɧɵɯ ɮɭɧɤɰɢɣ ɦɧɨɝɢɯ
ɩɟɪɟɦɟɧɧɵɯ (ɫɦ., ɧɚɩɪɢɦɟɪ, ɑɭ ɢ ɏɟɣɥ, 1982). ȼ ɨɞɧɨɦɟɪɧɨɦ ɫɥɭɱɚɟ ɷɬɭ ɬɟɨɪɟɦɭ
ɦɨɠɧɨ ɫɮɨɪɦɭɥɢɪɨɜɚɬɶ ɫɥɟɞɭɸɳɢɦ ɨɛɪɚɡɨɦ:
Ʌɟɦɦɚ. (Ɍɟɨɪɟɦɚ ɨ ɧɟɹɜɧɨɣ ɮɭɧɤɰɢɢ ɜ R
1
.) ɉɭɫɬɶ f(x
0
,r
0
) = 0 ɢ f ɩɪɢɧɚɞɥɟɠɢɬ
ɤɥɚɫɫɭ ɋ
1
ɜ ɧɟɤɨɬɨɪɨɣ ɨɬɤɪɵɬɨɣ ɨɤɪɟɫɬɧɨɫɬɢ ɬɨɱɤɢ (x
0
,r
0
) ɧɚ ɩɥɨɫɤɨɫɬɢ (x,r). Ɍɨɝɞɚ
ɟɫɥɢ f
x
≠0, ɬɨ ɫɭɳɟɫɬɜɭɸɬ ɬɚɤɢɟ
α
,
β
>0, ɱɬɨ (I) ɜɫɹɤɢɣ ɪɚɡ, ɤɨɝɞɚ x
0
-
β
< ɯ < ɯ
0
+
β
ɢ
r
0
-
α
< r < r
0
+
α
, ɭɪɚɜɧɟɧɢɟ f(x, r) = 0 ɢɦɟɟɬ ɟɞɢɧɫɬɜɟɧɧɨɟ ɪɟɲɟɧɢɟ ɯ = ɯ(r), ɢ (II)
ɫɭɳɟɫɬɜɭɟɬ x
r
(r), ɩɪɢɱɟɦ x
r
(r) = -f
r
(x(r)/f
x
(x(r),r).
Ɇɨɠɧɨ ɩɪɨɜɟɫɬɢ ɫɥɟɞɭɸɳɭɸ ɤɥɚɫɫɢɮɢɤɚɰɢɸ ɬɨɱɟɤ, ɩɪɢɧɚɞɥɟɠɚɳɢɯ ɤɪɢɜɵɦ
ɪɟɲɟɧɢɣ (ɫɦ. Ƀɨɫɫ ɢ Ⱦɠɨɡɟɮ, 1980, Ȼɪɢɬɬɨɧ, 1986).
Ɉɩɪɟɞɟɥɟɧɢɟ 3.7.1. (Ɉɞɧɨɦɟɪɧɵɣ ɫɥɭɱɚɣ.)
i
Ɋɟɝɭɥɹɪɧɨɣ ɬɨɱɤɨɣ (x
0
,r
0
) ɞɥɹ f(x, r) = 0 ɧɚɡɵɜɚɟɬɫɹ ɬɨɱɤɚ, ɜ ɤɨɬɨɪɨɣ ɥɢɛɨ
f
x
≠ 0, ɥɢɛɨ f
r
≠ 0. Ɋɟɝɭɥɹɪɧɨɣ ɬɨɱɤɨɣ ɩɨɜɨɪɨɬɚ ɧɚɡɵɜɚɟɬɫɹ ɬɚɤɚɹ ɪɟɝɭɥɹɪɧɚɹ
ɬɨɱɤɚ, ɜ ɤɨɬɨɪɨɣ r
x
(ɯ) ɢɡɦɟɧɹɟɬ ɡɧɚɤ. ɇɚ ɪɢɫ. 3.11a ɩɪɟɞɫɬɚɜɥɟɧ ɫɥɭɱɚɣ f
x
= 0
ɩɪɢ f
r
≠ 0 ɜ ɬɨɱɤɟ Ɋ.