Е. Деза_ М.М. Деза. Энциклопедический словарь расстояний (2008) (1185330), страница 47
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чÌÌÓ ÏÂÚ˘ÂÒÍÓ ÔÓÒÚ‡ÌÒÚ‚Ó fl‚ÎflÂÚÒfl ÔÓÎÌ˚Ï, ÂÒÎË Ú‡ÍÓ‚˚Ïfl‚ÎflÂÚÒfl ÔÓÒÚ‡ÌÒÚ‚Ó W. ÖÒÎË ÔÓÒÚ‡ÌÒÚ‚Ó V = W ÔÓÎÌÓÂ, ÚÓ ÔÓÒÚ‡ÌÒÚ‚ÓB(V, V) ÂÒÚ¸ ·‡Ì‡ıÓ‚‡ ‡Î„·‡, ÔÓÒÍÓθÍÛ ÓÔ‡ÚÓ̇fl ÌÓχ fl‚ÎflÂÚÒfl ÒÛ·ÏÛθÚËÔÎË͇ÚË‚ÌÓÈ ÌÓÏÓÈ.208ó‡ÒÚ¸ III. ê‡ÒÒÚÓflÌËfl ‚ Í·ÒÒ˘ÂÒÍÓÈ Ï‡ÚÂχÚËÍÂãËÌÂÈÌ˚È ÓÔ‡ÚÓ T : V → W ËÁ ·‡Ì‡ıÓ‚‡ ÔÓÒÚ‡ÌÒÚ‚‡ V ‚ ‰Û„Ó ·‡Ì‡ıÓ‚ÓÔÓÒÚ‡ÌÒÚ‚Ó W ̇Á˚‚‡ÂÚÒfl ÍÓÏÔ‡ÍÚÌ˚Ï, ÂÒÎË ÓÚÓ·‡ÊÂÌË β·Ó„Ó Ó„‡Ì˘ÂÌÌÓ„Ó ÔÓ‰ÏÌÓÊÂÒÚ‚‡ ÏÌÓÊÂÒÚ‚‡ V – ÓÚÌÓÒËÚÂθÌÓ ÍÓÏÔ‡ÍÚÌÓ ÔÓ‰ÏÌÓÊÂÒÚ‚Ó ÏÌÓÊÂÒÚ‚‡ W. ã˛·ÓÈ ÍÓÏÔ‡ÍÚÌ˚È ÓÔ‡ÚÓ fl‚ÎflÂÚÒfl Ó„‡Ì˘ÂÌÌ˚Ï (Ë, ÒΉӂ‡ÚÂθÌÓ,ÌÂÔÂ˚‚Ì˚Ï). èÓÒÚ‡ÌÒÚ‚Ó (K(V, W), || ⋅ ||) ̇ ÏÌÓÊÂÒÚ‚Â K(V, W) ‚ÒÂı ÍÓÏÔ‡ÍÚÌ˚ı ÓÔ‡ÚÓÓ‚ ËÁ V ‚ W Ò ÓÔ‡ÚÓÌÓÈ ÌÓÏÓÈ || ⋅ || ̇Á˚‚‡ÂÚÒfl ÔÓÒÚ‡ÌÒÚ‚ÓÏÍÓÏÔ‡ÍÚÌ˚ı ÓÔ‡ÚÓÓ‚.åÂÚË͇ fl‰ÂÌÓÈ ÌÓÏ˚èÛÒÚ¸ B(V, W) – ÔÓÒÚ‡ÌÒÚ‚Ó ‚ÒÂı Ó„‡Ì˘ÂÌÌ˚ı ÎËÌÂÈÌ˚ı ÓÔ‡ÚÓÓ‚, ÓÚÓ·‡Ê‡˛˘Ëı ·‡Ì‡ıÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó (V, || ⋅ ||V ) ‚ ‰Û„Ó ·‡Ì‡ıÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó(W, || ⋅ ||W).
é·ÓÁ̇˜ËÏ ·‡Ì‡ıÓ‚Ó ‰‚ÓÈÒÚ‚ÂÌÌÓ ÔÓÒÚ‡ÌÒÚ‚Ó ‰Îfl V Í‡Í V' ËÁ̇˜ÂÌË ÙÛÌ͈ËÓ̇· x' ∈ V' ‚ ÚӘ͠x ∈ V Í‡Í 〈x, x'〉. ãËÌÂÈÌ˚È ÓÔ‡ÚÓ T ∈∈ B(V, W) ̇Á˚‚‡ÂÚÒfl fl‰ÂÌ˚Ï ÓÔ‡ÚÓÓÏ, ÂÒÎË Â„Ó ÏÓÊÌÓ Ô‰ÒÚ‡‚ËÚ¸ ‚ ‚ˉÂx a T ( x) =∞∑〈 x, xi′〉 yi , „‰Â {xi′}i Ë {yi}i fl‚Îfl˛ÚÒfl ÔÓÒΉӂ‡ÚÂθÌÓÒÚflÏË ‚ V' Ë Wi =1∞ÒÓÓÚ‚ÂÚÒÚ‚ÂÌÌÓ, Ú‡ÍËÏË ˜ÚÓ∑i =1|| xi′ ||V ′ || yi ||W < ∞. чÌÌÓ Ô‰ÒÚ‡‚ÎÂÌË ̇Á˚-‚‡ÂÚÒfl fl‰ÂÌ˚Ï Ë ÏÓÊÂÚ ‡ÒÒχÚË‚‡Ú¸Òfl Í‡Í Ô‰ÒÚ‡‚ÎÂÌËÂ í ‚ ‚ˉ ÒÛÏÏ˚ÓÔ‡ÚÓÓ‚ ‡Ì„‡ 1 (Ú.Â.
Ò Ó‰ÌÓÏÂÌ˚Ï ÏÌÓÊÂÒÚ‚ÓÏ Á̇˜ÂÌËÈ). ü‰Â̇fl ÌÓχÓÔ‡ÚÓ‡ í ÓÔ‰ÂÎflÂÚÒfl ͇Í|| T || ÔËÒ = inf∞∑i =1|| xi′ ||V ′ || yi ||W ,„‰Â ËÌÙËÏÛÏ ·ÂÂÚÒfl ÔÓ ‚ÒÂÏ ‚ÓÁÏÓÊÌ˚Ï fl‰ÂÌ˚Ï Ô‰ÒÚ‡‚ÎÂÌËflÏ í.åÂÚË͇ fl‰ÂÌÓÈ ÌÓÏ˚ ÂÒÚ¸ ÏÂÚË͇ ÌÓÏ˚ || T – P || ÔËÒ Ì‡ ÏÌÓÊÂÒÚ‚Â N(V, W)‚ÒÂı fl‰ÂÌ˚ı ÓÔ‡ÚÓÓ‚, ÓÚÓ·‡Ê‡˛˘Ëı V ‚ W. èÓÒÚ‡ÌÒÚ‚Ó (N(V, W), || ⋅ ||ÔËÒ)̇Á˚‚‡ÂÚÒfl ÔÓÒÚ‡ÌÒÚ‚ÓÏ fl‰ÂÌ˚ı ÓÔ‡ÚÓÓ‚ Ë fl‚ÎflÂÚÒfl ·‡Ì‡ıÓ‚˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ.ü‰ÂÌÓ ÔÓÒÚ‡ÌÒÚ‚Ó ÓÔ‰ÂÎflÂÚÒfl Í‡Í ÎÓ͇θÌÓ ‚˚ÔÛÍÎÓ ÔÓÒÚ‡ÌÒÚ‚Ó, ‰ÎflÍÓÚÓÓ„Ó ‚Ò ÌÂÔÂ˚‚Ì˚ ÎËÌÂÈÌ˚ ÙÛÌ͈ËË Ì‡ ÔÓËÁ‚ÓθÌÓÏ ·‡Ì‡ıÓ‚ÓÏ ÔÓÒÚ‡ÌÒÚ‚Â – fl‰ÂÌ˚ ÓÔ‡ÚÓ˚.
ü‰ÂÌÓ ÔÓÒÚ‡ÌÒÚ‚Ó ÒÚÓËÚÒfl Í‡Í ÔÓÂÍÚË‚Ì˚ÈÔ‰ÂÎ „Ëθ·ÂÚÓ‚˚ı ÔÓÒÚ‡ÌÒÚ‚ H α Ò Ú‡ÍËÏ Ò‚ÓÈÒÚ‚ÓÏ, ˜ÚÓ ‰Îfl Í‡Ê‰Ó„Ó α ∈ IÏÓÊÌÓ Ì‡ÈÚË β ∈ I, Ú‡ÍÓ ˜ÚÓ H β ⊂ H α Ë ÓÔ‡ÚÓ ‚ÎÓÊÂÌËfl Hβ x → x ∈ H αfl‚ÎflÂÚÒfl ÓÔ‡ÚÓÓÏ ÉËθ·ÂÚ‡-òÏˉڇ.
çÓÏËÓ‚‡ÌÌÓ ÔÓÒÚ‡ÌÒÚ‚Ó fl‚ÎflÂÚÒfl fl‰ÂÌ˚Ï ÚÓ„‰‡ Ë ÚÓθÍÓ ÚÓ„‰‡, ÍÓ„‰‡ ÓÌÓ ÍÓ̘ÌÓÏÂÌÓ.åÂÚË͇ ÍÓ̘ÌÓÈ fl‰ÂÌÓÈ ÌÓÏ˚èÛÒÚ¸ F(V, W) – ÔÓÒÚ‡ÌÒÚ‚Ó ‚ÒÂı ÎËÌÂÈÌ˚ı ÓÔ‡ÚÓÓ‚ ÍÓ̘ÌÓ„Ó ‡Ì„‡(Ú.Â. Ò ÍÓ̘ÌÓÏÂÌ˚Ï ÏÌÓÊÂÒÚ‚ÓÏ Á̇˜ÂÌËÈ), ÓÚÓ·‡Ê‡˛˘Ëı ·‡Ì‡ıÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó (V, || ⋅ ||V) ‚ ‰Û„Ó ·‡Ì‡ıÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó (W, || ⋅ ||W). ãËÌÂÈÌ˚È ÓÔ‡ÚÓnT ∈ F(V, W) ÏÓÊÌÓ Ô‰ÒÚ‡‚ËÚ¸ ‚ ‚ˉ x a T ( x ) =∑〈 x, xi′〉 yi , „‰Â {xi′}i Ë {yi}ii =1fl‚Îfl˛ÚÒfl ÔÓÒΉӂ‡ÚÂθÌÓÒÚflÏË ËÁ V' (·‡Ì‡ıÓ‚‡ ‰‚ÓÈÒÚ‚ÂÌÌÓ„Ó ÔÓÒÚ‡ÌÒÚ‚‡ ‰ÎflV) Ë W ÒÓÓÚ‚ÂÚÒÚ‚ÂÌÌÓ, ‡ 〈x, x'〉 – Á̇˜ÂÌËÂÏ ÙÛÌ͈ËÓ̇· x' ∈ V' ̇ ‚ÂÍÚÓ x ∈ V.209É·‚‡ 13. ê‡ÒÒÚÓflÌËfl ‚ ÙÛÌ͈ËÓ̇θÌÓÏ ‡Ì‡ÎËÁÂäÓ̘̇fl fl‰Â̇fl ÌÓχ í ÓÔ‰ÂÎflÂÚÒfl ͇Ín|| T || fÔËÒ = inf∑i =1|| xi′ ||V ′ || yi ||W ,„‰Â ËÌÙËÏÛÏ ·ÂÂÚÒfl ÔÓ ‚ÒÂÏ ‚ÓÁÏÓÊÌ˚Ï ÍÓ̘Ì˚Ï Ô‰ÒÚ‡‚ÎÂÌËflÏ í .åÂÚË͇ ÍÓ̘ÌÓÈ fl‰ÂÌÓÈ ÌÓÏ˚ ÂÒÚ¸ ÏÂÚË͇ ÌÓÏ˚ || T – P ||f ÔËÒ Ì‡ ÏÌÓÊÂÒÚ‚Â F( V, W).
èÓÒÚ‡ÌÒÚ‚Ó F(V, W), || ⋅ ||f ÔËÒ) ̇Á˚‚‡ÂÚÒfl ÔÓÒÚ‡ÌÒÚ‚ÓÏfl‰ÂÌ˚ı ÓÔ‡ÚÓÓ‚ ÍÓ̘ÌÓ„Ó ‡Ì„‡. éÌÓ fl‚ÎflÂÚÒfl ÔÎÓÚÌ˚Ï ÎËÌÂÈÌ˚ÏÔÓ‰ÔÓÒÚ‡ÌÒÚ‚ÓÏ ÔÓÒÚ‡ÌÒÚ‚‡ fl‰ÂÌ˚ı ÓÔ‡ÚÓÓ‚ N( V, W).(åÂÚË͇ ÌÓÏ˚ ÉËθ·ÂÚ‡–òÏˉڇê‡ÒÒÏÓÚËÏ ÏÌÓÊÂÒÚ‚Ó ‚ÒÂı ÎËÌÂÈÌ˚ı ÓÔ‡ÚÓÓ‚ ËÁ „Ëθ·ÂÚÓ‚‡ ÔÓÒÚ‡ÌÒÚ‚‡H1 ,|| ⋅ || H1 ‚ „Ëθ·ÂÚÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó H2 ,|| ⋅ || H 2 .
çÓχ ÉËθ·ÂÚ‡–òÏˉڇ)()|| T ||HS ÎËÌÂÈÌÓ„Ó ÓÔ‡ÚÓ‡ T : H1 →H2 Á‡‰‡ÂÚÒfl ͇Í|| T ||HS = || T (eα ) ||2H 2 α ∈I∑1/ 2,„‰Â (e α ) α ∈ I – ÓÚÓ„ÓÌÓÏËÓ‚‡ÌÌ˚È ·‡ÁËÒ ‚ ç1 . ãËÌÂÈÌ˚È ÓÔ‡ÚÓ T : H 1 → H2̇Á˚‚‡ÂÚÒfl ÓÔ‡ÚÓÓÏ ÉËθ·ÂÚ‡–òÏˉڇ, ÂÒÎË || T ||2HS < ∞.åÂÚË͇ ÌÓÏ˚ ÉËθ·ÂÚ‡–òÏˉڇ ÂÒÚ¸ ÏÂÚË͇ ÌÓÏ˚ || T – P ||HS ̇ ÏÌÓÊÂÒÚ‚Â S(H1, H2) ‚ÒÂı ÓÔ‡ÚÓÓ‚ ÉËθ·ÂÚ‡–òÏˉڇ ËÁ H1 ‚ H2.ÑÎfl H1 = H2 = H ‡Î„·‡ S(H, H) = S(H) Ò ÌÓÏÓÈ ÉËθ·ÂÚ‡–òÏˉڇ fl‚ÎflÂÚÒfl ·‡Ì‡ıÓ‚ÓÈ ‡Î„·ÓÈ. é̇ ÒÓ‰ÂÊËÚ Í‡Í ÔÎÓÚÌÓ ÔÓ‰ÏÌÓÊÂÒÚ‚Ó ÓÔ‡ÚÓ˚ ÍÓ̘ÌÓ„Ó ‡Ì„‡ Ë ÔË̇‰ÎÂÊËÚ ÔÓÒÚ‡ÌÒÚ‚Û K(H) ÍÓÏÔ‡ÍÚÌ˚ı ÓÔ‡ÚÓÓ‚. ë͇ÎflÌÓ ÔÓËÁ‚‰ÂÌË 〈, 〉HS ̇ S(H ) ÓÔ‰ÂÎflÂÚÒfl Í‡Í Ë 〈T, P〉 HS =/2=〈T (eα ), P(eα )〉 Ë || T ||HS = 〈T , T 〉1HS. ëΉӂ‡ÚÂθÌÓ, S(H) fl‚ÎflÂÚÒfl „Ëθ·ÂÚÓ-∑α ∈l‚˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ (ÌÂÁ‡‚ËÒËÏÓ ÓÚ ‚˚·Ó‡ ·‡ÁËÒ‡ (eα)α ∈ l).åÂÚË͇ ÌÓÏ˚ ÓÔ‡ÚÓÓ‚ ÒÓ ÒΉÓÏÑÎfl „Ëθ·ÂÚÓ‚‡ ÔÓÒÚ‡ÌÒÚ‚‡ ç ÌÓχ ÓÔ‡ÚÓÓ‚ ÒÓ ÒΉÓÏ ‰Îfl ÎËÌÂÈÌÓ„ÓÓÔ‡ÚÓ‡ T : H → H Á‡‰‡ÂÚÒfl ͇Í|| T ||tc =∑〈| T | (eα ), eα 〉,α ∈I„‰Â | T | – ‡·ÒÓβÚÌÓ Á̇˜ÂÌËÂ í ‚ ·‡Ì‡ıÓ‚ÓÈ ‡Î„· B(X) ‚ÒÂı Ó„‡Ì˘ÂÌÌ˚ıÓÔ‡ÚÓÓ‚ ËÁ ç ‚ Ò·fl, ‡ (eα)α ∈ l – ÓÚÓ„ÓÌÓÏËÓ‚‡ÌÌ˚È ·‡ÁËÒ ‚ ç.
éÔ‡ÚÓT : H → H ̇Á˚‚‡ÂÚÒfl ÓÔ‡ÚÓÓ‚ ÒÓ ÒΉÓÏ, ÂÒÎË || T ||tc < ∞. ã˛·ÓÈ Ú‡ÍÓÈÓÔ‡ÚÓ fl‚ÎflÂÚÒfl ÔÓËÁ‚‰ÂÌËÂÏ ‰‚Ûı ÓÔ‡ÚÓÓ‚ ÉËθ·ÂÚ‡–òÏˉڇ.åÂÚË͇ ÌÓÏ˚ ÓÔ‡ÚÓÓ‚ ÒÓ ÒΉÓÏ – ÏÂÚË͇ ÌÓÏ˚ || T – P ||tc ̇ ÏÌÓÊÂÒÚ‚ÂL(H) ‚ÒÂı ÓÔ‡ÚÓÓ‚ ÒÓ ÒΉÓÏ ËÁ ç ‚ Ò·fl. åÌÓÊÂÒÚ‚Ó L(H) Ò ÌÓÏÓÈ || ⋅ ||tcÓ·‡ÁÛÂÚ ·‡Ì‡ıÓ‚Û ‡Î„·Û, ÍÓÚÓ‡fl ÒÓ‰ÂÊËÚÒfl ‚ ‡Î„· K(H) (‚ÒÂı ÍÓÏÔ‡ÍÚÌ˚ıÓÔ‡ÚÓÓ‚ ËÁ ç ‚ Ò·fl), Ë ÒÓ‰ÂÊËÚ ‡Î„Â·Û S(H) (‚ÒÂı ÓÔ‡ÚÓÓ‚ ÉËθ·ÂÚ‡–òÏˉڇ ËÁ ç ‚ Ò·fl).åÂÚË͇ ÌÓÏ˚ -Í·ÒÒ‡ ò‡ÚÂ̇ÇÓÁ¸ÏÂÏ 1 ≤ p < ∞. ÑÎfl ÒÂÔ‡‡·ÂθÌÓ„Ó „Ëθ·ÂÚÓ‚‡ ÔÓÒÚ‡ÌÒÚ‚‡ ç ÌÓχ210ó‡ÒÚ¸ III. ê‡ÒÒÚÓflÌËfl ‚ Í·ÒÒ˘ÂÒÍÓÈ Ï‡ÚÂχÚËÍÂ-Í·ÒÒ‡ ò‡ÚÂ̇ ÍÓÏÔ‡ÍÚÌÓ„Ó ÎËÌÂÈÌÓ„Ó ÓÔ‡ÚÓ‡ T : H → H ÓÔ‰ÂÎflÂÚÒfl ͇Í|| Tp||Sch=∑n| sn | 1/ pp,„‰Â {sn}n – ÔÓÒΉӂ‡ÚÂθÌÓÒÚ¸ ÒËÌ„ÛÎflÌ˚ı Á̇˜ÂÌËÈ ÓÔ‡ÚÓ‡ í. äÓÏÔ‡ÍÚÌ˚ÈpÓÔ‡ÚÓ T : H → H ̇Á˚‚‡ÂÚÒfl ÓÔ‡ÚÓÓÏ -Í·ÒÒ‡ ò‡ÚÂ̇, ÂÒÎË || T ||Sch< ∞.påÂÚËÍÓÈ ÌÓÏ˚ -Í·ÒÒ‡ ò‡ÚÚ Â̇ ̇Á˚‚‡ÂÚÒfl ÏÂÚË͇ ÌÓÏ˚ || T − P ||ScḣÏÌÓÊÂÒÚ‚Â Sp (H) ‚ÒÂı ÓÔ‡ÚÓÓ‚ -Í·ÒÒ‡ ò‡ÚÂ̇ ËÁ ç ̇ Ò·fl.
åÌÓÊÂÒÚ‚Ó Sp(H) ÒpÌÓÏÓÈ || ⋅ ||SchÓ·‡ÁÛÂÚ ·‡Ì‡ıÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó. S1 (H) fl‚ÎflÂÚÒfl Í·ÒÒÓÏ ÓÔ‡ÚÓÓ‚ ÒÓ ÒΉÓÏ ‰Îfl ç Ë S 2(H) fl‚ÎflÂÚÒfl Í·ÒÒÓÏ ÓÔ‡ÚÓÓ‚ ÉËθ·ÂÚ‡–òÏˉڇ‰Îfl ç (ÒÏ. Ú‡ÍÊ åÂÚË͇ ÌÓÏ˚ ò‡ÚÂ̇, „Î. 12).çÂÔÂ˚‚ÌÓ ‰‚ÓÈÒÚ‚ÂÌÌÓ ÔÓÒÚ‡ÌÒÚ‚ÓèÛÒÚ¸ (V, || ⋅ ||) – ÌÓÏËÓ‚‡ÌÌÓ ‚ÂÍÚÓÌÓ ÔÓÒÚ‡ÌÒÚ‚Ó. èÛÒÚ¸ V' – ÏÌÓÊÂÒÚ‚Ó ‚ÒÂı ÌÂÔÂ˚‚Ì˚ı ÎËÌÂÈÌ˚ı ÙÛÌ͈ËÓ̇ÎÓ‚ í ËÁ V ‚ ÓÒÌÓ‚ÌÓ ÔÓΠ( ËÎË ) ËÔÛÒÚ¸ || ⋅ ||' – ÓÔ‡ÚÓ̇fl ÌÓχ ̇ V', ÓÔ‰ÂÎÂÌ̇fl ͇Í|| T ||′= sup | T ( x ) | .|| x ||≤1èÓÒÚ‡ÌÒÚ‚Ó (V', || ⋅ ||') fl‚ÎflÂÚÒfl ·‡Ì‡ıÓ‚˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ, ÍÓÚÓÓ ̇Á˚‚‡ÂÚÒflÌÂÔÂ˚‚Ì˚Ï ‰‚ÓÈÒÚ‚ÂÌÌ˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ (ËÎË ·‡Ì‡ıÓ‚˚Ï ‰‚ÓÈÒÚ‚ÂÌÌ˚ÏÔÓÒÚ‡ÌÒÚ‚ÓÏ) ÔÓÒÚ‡ÌÒÚ‚‡ (V, || ⋅ ||).í‡Í, ÌÂÔÂ˚‚Ì˚Ï ‰‚ÓÈÒÚ‚ÂÌÌ˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ ‰Îfl ÏÂÚ˘ÂÒÍÓ„Ó ÔÓÒÚ‡ÌÒÚ‚‡ l pn (l p∞ ) fl‚ÎflÂÚÒfl lqn (lq∞ ) ÒÓÓÚ‚ÂÚÒÚ‚ÂÌÌÓ.
é·‡ ÌÂÔÂ˚‚Ì˚ı ‰‚ÓÈÒÚ‚ÂÌÌ˚ı ÔÓÒÚ‡ÌÒÚ‚‡ ‰Îfl ·‡Ì‡ıÓ‚˚ı ÔÓÒÚ‡ÌÒÚ‚ ë (ÒÓÒÚÓfl˘Â„Ó ËÁ ‚ÒÂı ÒıÓ‰fl˘ËıÒfl ÔÓÒΉӂ‡ÚÂθÌÓÒÚÂÈ Ò l-ÏÂÚËÍÓÈ) Ë C 0 (ÒÓÒÚÓfl˘Â„Ó ËÁ ‚ÒÂı ÔÓÒΉӂ‡ÚÂθÌÓÒÚÂÈ (Òl-ÏÂÚËÍÓÈ), ÒıÓ‰fl˘ËıÒfl Í ÌÛβ) ÂÒÚÂÒÚ‚ÂÌÌ˚Ï Ó·‡ÁÓÏ ÓÚÓʉÂÒÚ‚Îfl˛ÚÒfl Ò l1∞ .èÓÒÚÓflÌ̇fl ‡ÒÒÚÓflÌËfl ÓÔ‡ÚÓÓÌÓÈ ‡Î„·˚èÛÒÚ¸ – ÓÔ‡ÚÓ̇fl ‡Î„·‡ ÒÓ‰Âʇ˘‡flÒfl ‚ B(H) – ÏÌÓÊÂÒÚ‚e ‚ÒÂı Ó„‡Ì˘ÂÌÌ˚ı ÓÔ‡ÚÓÓ‚ ̇ „Ëθ·ÂÚÓ‚ÓÏ ÔÓÒÚ‡ÌÒÚ‚Â ç. ÑÎfl β·Ó„Ó ÓÔ‡ÚÓ‡ T ∈∈ B(H) ÔÛÒÚ¸ β(T, A) = sup{|| P⊥ TP||; P – ÔÓÂ͈Ëfl Ë P ⊥ P = (0)}.
èÛÒÚ¸ dist(T, ) ÂÒÚ¸‡ÒÒÚÓflÌË ÏÂÊ‰Û ÓÔ‡ÚÓÓÏ í Ë ‡Î„·ÓÈ , Ú.Â. ̇ËÏÂ̸¯‡fl ÌÓχ ÓÔ‡ÚÓ‡T – A, „‰Â Ä Ôӷ„‡ÂÚ . ç‡ËÏÂ̸¯‡fl ÔÓÎÓÊËÚÂθ̇fl ÔÓÒÚÓflÌ̇fl ë (ÂÒÎË Ó̇ÒÛ˘ÂÒÚ‚ÛÂÚ) ڇ͇fl ˜ÚÓ ‰Îfl β·Ó„Ó ÓÔ‡ÚÓ‡ T ∈ B(H) ‚˚ÔÓÎÌflÂÚÒfl ̇‚ÂÌÒÚ‚Ódist(T, ) ≤ C(T, ),̇Á˚‚‡ÂÚÒfl ÔÓÒÚÓflÌÌÓÈ ‡ÒÒÚÓflÌËfl ‰Îfl ‡Î„·˚ .É·‚‡ 14ê‡ÒÒÚÓflÌËfl ‚ ÚÂÓËË ‚ÂÓflÚÌÓÒÚÂÈèÓÒÚ‡ÌÒÚ‚ÓÏ ‚ÂÓflÚÌÓÒÚÂÈ Ì‡Á˚‚‡ÂÚÒfl ËÁÏÂËÏÓ ÔÓÒÚ‡ÌÒÚ‚Ó (Ω, , P),„‰Â ÂÒÚ¸ ÏÌÓÊÂÒÚ‚Ó ‚ÒÂı ËÁÏÂËÏ˚ı ÔÓ‰ÏÌÓÊÂÒÚ‚ ÏÌÓÊÂÒÚ‚‡ Ω, ‡ P – χ ̇ Ò P(Ω) = 1. åÌÓÊÂÒÚ‚Ó Ω Ì‡Á˚‚‡ÂÚÒfl ÔÓÒÚ‡ÌÒÚ‚ÓÏ ‚˚·ÓÓÍ. ùÎÂÏÂÌÚ a ∈ ̇Á˚‚‡ÂÚÒfl ÒÓ·˚ÚËÂÏ, ‚ ˜‡ÒÚÌÓÒÚË, ˝ÎÂÏÂÌÚ‡ÌÓ ÒÓ·˚ÚË – ˝ÚÓ ÔÓ‰ÏÌÓÊÂÒÚ‚Ó ÏÌÓÊÂÒÚ‚‡ Ω , ÒÓ‰Âʇ˘Â ÚÓθÍÓ Ó‰ËÌ ˝ÎÂÏÂÌÚ; P(a) ̇Á˚‚‡ÂÚÒfl‚ÂÓflÚÌÓÒÚ¸˛ ÒÓ·˚ÚËfl ‡. å‡ ê ̇ ̇Á˚‚‡ÂÚÒfl ‚ÂÓflÚÌÓÒÚÌÓÈ ÏÂÓÈ, ËÎËÁ‡ÍÓÌÓÏ ‡ÒÔ‰ÂÎÂÌËfl (‚ÂÓflÚÌÓÒÚÂÈ), ËÎË ÔÓÒÚÓ ‡ÒÔ‰ÂÎÂÌËÂÏ (‚ÂÓflÚÌÓÒÚÂÈ).ëÎÛ˜‡È̇fl ‚Â΢Ë̇ ï ÂÒÚ¸ ËÁÏÂËχfl ÙÛÌ͈Ëfl ËÁ ÔÓÒÚ‡ÌÒÚ‚‡ ‚ÂÓflÚÌÓÒÚÂÈ(Ω, , P ) ‚ ËÁÏÂËÏÓ ÔÓÒÚ‡ÌÒÚ‚Ó, ̇Á˚‚‡ÂÏÓ ÔÓÒÚ‡ÌÒÚ‚ÓÏ ÒÓÒÚÓflÌËÈ‚ÓÁÏÓÊÌ˚ı Á̇˜ÂÌËÈ ÔÂÂÏÂÌÌÓÈ; Ó·˚˜ÌÓ ·ÂÛÚÒfl ‰ÂÈÒÚ‚ËÚÂθÌ˚ ˜ËÒ· Ò ·ÓÂ΂ÓÈ α-‡Î„·ÓÈ, Ú‡Í ˜ÚÓ X : Ω → .
åÌÓÊÂÒÚ‚Ó Á̇˜ÂÌËÈ χ ÒÎÛ˜‡ÈÌÓÈ ‚Â΢ËÌ˚ï ̇Á˚‚‡ÂÚÒfl ÌÂÒÛ˘ËÏ ÏÌÓÊÂÒÚ‚ÓÏ ‡ÒÔ‰ÂÎÂÌËfl ê; ˝ÎÂÏÂÌÚ x ∈ χ ̇Á˚‚‡ÂÚÒflÒÓÒÚÓflÌËÂÏ.á‡ÍÓÌ ‡ÒÔ‰ÂÎÂÌËfl ÏÓÊÌÓ Â‰ËÌÒÚ‚ÂÌÌ˚Ï Ó·‡ÁÓÏ ÓÔËÒ‡Ú¸ ˜ÂÂÁ ÍÛÏÛÎflÚË‚ÌÛ˛ ÙÛÌÍˆË˛ ‡ÒÔ‰ÂÎÂÌËfl (CDF, ÙÛÌÍˆË˛ ‡ÒÔ‰ÂÎÂÌËfl, ÍÛÏÛÎflÚË‚ÌÛ˛ÙÛÌÍˆË˛ ÔÎÓÚÌÓÒÚË) F(x), ÍÓÚÓ‡fl ÔÓ͇Á˚‚‡ÂÚ ‚ÂÓflÚÌÓÒÚ¸ ÚÓ„Ó, ˜ÚÓ ÒÎÛ˜‡È̇fl‚Â΢Ë̇ ï ÔËÌËχÂÚ Á̇˜ÂÌË Ì ·Óθ¯Â, ˜ÂÏ ı: F (x) = P (X ≤ x) = P (ω ∈∈ Ω: X(ω) < x).í‡ÍËÏ Ó·‡ÁÓÏ, β·‡fl ÒÎÛ˜‡È̇fl ‚Â΢Ë̇ ï ÔÓÓʉ‡ÂÚ Ú‡ÍÓ ‡ÒÔ‰ÂÎÂÌË‚ÂÓflÚÌÓÒÚÂÈ, ÍÓÚÓ˚Ï ËÌÚ‚‡ÎÛ [a, b] ÒÚ‡‚ËÚÒfl ‚ ÒÓÓÚ‚ÂÚÒÚ‚Ë ‚ÂÓflÚÌÓÒÚ¸P(a ≤ X ≤ b) = P(ω ∈ Ω: a ≤ X(ω) ≤ b), Ú.Â.
‚ÂÓflÚÌÓÒÚ¸, ˜ÚÓ ‚Â΢Ë̇ ï ·Û‰ÂÚ ËÏÂÚ¸Á̇˜ÂÌË ‚ ËÌÚ‚‡Î [a, b].ê‡ÒÔ‰ÂÎÂÌË ̇Á˚‚‡ÂÚÒfl ‰ËÒÍÂÚÌ˚Ï, ÂÒÎË F(x) ÒÓÒÚÓËÚ ËÁ ÔÓÒΉӂ‡ÚÂθÌÓÒÚË ÍÓ̘Ì˚ı Ò͇˜ÍÓ‚ ÔË xi; ‡ÒÔ‰ÂÎÂÌË ̇Á˚‚‡ÂÚÒfl ÌÂÔÂ˚‚Ì˚Ï, ÂÒÎË F(x)ÌÂÔÂ˚‚̇. å˚ ‡ÒÒχÚË‚‡ÂÏ (Í‡Í ‚ ·Óθ¯ËÌÒÚ‚Â ÔËÎÓÊÂÌËÈ) ÚÓθÍÓ ‰ËÒÍÂÚÌ˚ ËÎË ‡·ÒÓβÚÌÓ ÌÂÔÂ˚‚Ì˚ ‡ÒÔ‰ÂÎÂÌËfl, Ú.Â. ÙÛÌ͈Ëfl ‡ÒÔ‰ÂÎÂÌËflF : → fl‚ÎflÂÚÒfl ‡·ÒÓβÚÌÓ ÌÂÔÂ˚‚ÌÓÈ. ùÚÓ ÓÁ̇˜‡ÂÚ, ˜ÚÓ ‰Îfl Í‡Ê‰Ó„Ó ˜ËÒ·ε > 0 ÒÛ˘ÂÒÚ‚ÛÂÚ Ú‡ÍÓ ˜ËÒÎÓ δ > 0, ˜ÚÓ ‰Îfl β·ÓÈ ÔÓÒΉӂ‡ÚÂθÌÓÒÚË ÔÓÔ‡ÌÓÌÂÔÂÂÒÂ͇˛˘ËıÒfl ËÌÚ‚‡ÎÓ‚ [xk, yk ], 1 ≤ k ≤ n ̇‚ÂÌÒÚ‚Ó( yk − x k ) < δ∑‚ΘÂÚ Ì‡‚ÂÌÒÚ‚Ó∑1≤ k ≤ n| F( yk ) − F( x k ) | < ε.1≤ k ≤ ná‡ÍÓÌ ‡ÒÔ‰ÂÎÂÌËfl ÏÓÊÂÚ ·˚Ú¸ Ú‡ÍÊ ‰ËÌÒÚ‚ÂÌÌ˚Ï Ó·‡ÁÓÏ ÓÔ‰ÂÎÂ̘ÂÂÁ ÔÎÓÚÌÓÒÚ¸ ‡ÒÔ‰ÂÎÂÌËfl ‚ÂÓflÚÌÓÒÚÂÈ (PDF, ÙÛÌÍˆË˛ ÔÎÓÚÌÓÒÚË,ÙÛÌÍˆË˛ ‚ÂÓflÚÌÓÒÚË) (ı) ÒÓÓÚ‚ÂÚÒÚ‚Û˛˘ÂÈ ÒÎÛ˜‡ÈÌÓÈ ‚Â΢ËÌ˚.
ÑÎfl‡·ÒÓβÚÌÓ ÌÂÔÂ˚‚ÌÓ„Ó ‡ÒÔ‰ÂÎÂÌËfl ÙÛÌ͈Ëfl ‡ÒÔ‰ÂÎÂÌËfl fl‚ÎflÂÚÒfl ÔÓ˜ÚË‚Ò˛‰Û ‰ËÙÙÂÂ̈ËÛÂÏÓÈ Ë ÙÛÌ͈Ëfl ÔÎÓÚÌÓÒÚË ÓÔ‰ÂÎflÂÚÒfl Í‡Í ÔÓËÁ‚Ӊ̇fl212ó‡ÒÚ¸ III. ê‡ÒÒÚÓflÌËfl ‚ Í·ÒÒ˘ÂÒÍÓÈ Ï‡ÚÂχÚËÍÂxp(x) = F'(x) ÙÛÌ͈ËË ‡ÒÔ‰ÂÎÂÌËfl; ÒΉӂ‡ÚÂθÌÓ, F( x ) = P( X ≤ x ) =∫p(t )dt Ë−∞b∫p(t )dt = P( a ≤ X ≤ b). ÑÎfl ÒÎÛ˜‡fl ‰ËÒÍÂÚÌÓ„Ó ‡ÒÔ‰ÂÎÂÌËfl ÙÛÌ͈Ëfl ÔÎÓÚÌÓÒÚËa(ÔÎÓÚÌÓÒÚË ÒÎÛ˜‡ÈÌÓÈ ‚Â΢ËÌ˚ ï) ÓÔ‰ÂÎflÂÚÒfl Í‡Í Â Á̇˜ÂÌËfl p( xi ) = P( X = x ),Ú‡Í ˜ÚÓ F( x ) =∑p( xi ). Ç ÔÓÚË‚ÓÔÓÎÓÊÌÓÒÚ¸ ˝ÚÓÏÛ Í‡Ê‰Ó ˝ÎÂÏÂÌÚ‡ÌÓÂxi ≤ xÒÓ·˚ÚË ËÏÂÂÚ ‚ ÌÂÔÂ˚‚ÌÓÏ ÒÎÛ˜‡Â ‚ÂÓflÚÌÓÒÚ¸ ÌÓθ.ëÎÛ˜‡È̇fl ‚Â΢Ë̇ ï ÔËÏÂÌflÂÚÒfl ‰Îfl "ÔÂÂÌÓÒ‡" ÏÂ˚ ê ̇ Ω Ì‡ ÏÂÛ dF ̇. ëÓÓÚ‚ÂÚÒÚ‚Û˛˘Â ÔÓÒÚ‡ÌÒÚ‚Ó ‚ÂÓflÚÌÓÒÚÂÈ fl‚ÎflÂÚÒfl ÚÂıÌ˘ÂÒÍËÏ ËÌÒÚÛÏÂÌÚÓÏ, ÔËÏÂÌÂÌË ÍÓÚÓÓ„Ó Ó·ÂÒÔ˜˂‡ÂÚ ÒÛ˘ÂÒÚ‚Ó‚‡ÌË ÒÎÛ˜‡ÈÌ˚ı ‚Â΢ËÌ,‡ ËÌÓ„‰‡ ËÒÔÓθÁÛÂÚÒfl Ë ‰Îfl Ëı ÔÓÒÚÓÂÌËfl.Ç ÚÂÓËË ‚ÂÓflÚÌÓÒÚÂÈ ÏÂÚËÍË ÏÂÊ‰Û ‡ÒÔ‰ÂÎÂÌËflÏË Ì‡Á˚‚‡˛ÚÒfl ÔÓÒÚ˚ÏËÏÂÚË͇ÏË, ‡ ÏÂÚËÍË ÏÂÊ‰Û ÒÎÛ˜‡ÈÌ˚ÏË ‚Â΢Ë̇ÏË Ì‡Á˚‚‡˛ÚÒfl ÒÎÓÊÌ˚ÏËÏÂÚË͇ÏË [Rach91].