Е. Деза_ М.М. Деза. Энциклопедический словарь расстояний (2008) (1185330), страница 27
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í‡ÍË ÔÓÒÚ‡ÌÒÚ‚‡ ‚Íβ˜‡˛Ú ‚ Ò·fl ÔÓÒÚ‡ÌÒÚ‚‡ Ó„‡Ì˘ÂÌÌÓÈ ÍË‚ËÁÌ˚, ËχÌÓ‚˚ ÔÓÒÚ‡ÌÒÚ‚‡ Ë Ú.Ô. é·Ó·˘ÂÌÌ˚ ËχÌÓ‚˚ ÔÓÒÚ‡ÌÒÚ‚‡ ÓÚ΢‡˛ÚÒfl ÓÚ ËχÌÓ‚˚ı Ì ÚÓθÍÓ ·Óθ¯ÂÈ Ó·Ó·˘ÂÌÌÓÒÚ¸˛, ÌÓ Ë ÚÂÏ,˜ÚÓ ÓÌË ÓÔ‰ÂÎfl˛ÚÒfl Ë ËÒÒÎÂ‰Û˛ÚÒfl ÚÓθÍÓ Ì‡ ÓÒÌÓ‚Â Ëı ÏÂÚËÍË ·ÂÁ Û˜ÂÚ‡ÍÓÓ‰Ë̇Ú.èÓÒÚ‡ÌÒÚ‚Ó Ò Ó„‡Ì˘ÂÌÌÓÈ ÍË‚ËÁÌÓÈ (≤ k Ë ≥ k') fl‚ÎflÂÚÒfl Ó·Ó·˘ÂÌÌ˚ÏËχÌÓ‚˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ, ÍÓÚÓÓ ÓÔ‰ÂÎflÂÚÒfl ÒÎÂ‰Û˛˘ËÏ ÛÒÎÓ‚ËÂÏ: ‰Îflβ·ÓÈ ÔÓÒΉӂ‡ÚÂθÌÓÒÚË „ÂÓ‰ÂÁ˘ÂÒÍËı ÚÂÛ„ÓθÌËÍÓ‚ Tn, ÒÛʇ˛˘ËıÒfl ‚ ÚÓ˜ÍÛ,ËÏÂ˛Ú ÏÂÒÚÓ Ì‡‚ÂÌÒÚ‚‡k ≥ limδ (Tn )σ( )Tn0≥ limδ (Tn )( )σ Tn0≥ k ′,„‰Â „ÂÓ‰ÂÁ˘ÂÒÍËÈ ÚÂÛ„ÓθÌËÍ T = xyz fl‚ÎflÂÚÒfl ÚÓÈÍÓÈ „ÂÓ‰ÂÁ˘ÂÒÍËı ÓÚÂÁÍÓ‚[x, y], [y, z], [z, x] (ÒÚÓÓÌ˚ ÚÂÛ„ÓθÌË͇ í), ÒÓ‰ËÌfl˛˘Ëı ÔÓÔ‡ÌÓ ÚË ‡Á΢Ì˚ÂÚÓ˜ÍË x , y, z, ‚Â΢ËÌ˚ δ (T 0 ) = α + β + γ − π ‚˚‡Ê‡ÂÚ Û„ÎÓ‚ÓÈ ‰ÂÙÂÍÚ „ÂÓ‰ÂÁ˘ÂÒÍÓ„Ó ÚÂÛ„ÓθÌË͇ í Ë δ(T 0 ) – ÔÎÓ˘‡‰¸ ‚ÍÎˉӂ‡ ÚÂÛ„ÓθÌË͇ T0 ÒÓÒÚÓÓ̇ÏË ÚÓÈ Ê ‰ÎËÌ˚.
ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÔÓÒÚ‡ÌÒÚ‚Â Ó„‡Ì˘ÂÌÌÓÈÍË‚ËÁÌ˚ ̇Á˚‚‡ÂÚÒfl ÏÂÚËÍÓÈ Ó„‡Ì˘ÂÌÌÓÈ ÍË‚ËÁÌ˚. í‡ÍÓ ÔÓÒÚ‡ÌÒÚ‚ÓÔ‚‡˘‡ÂÚÒfl ‚ ËχÌÓ‚Ó, ÂÒÎË ‚˚ÔÓÎÌfl˛ÚÒfl ‰‚‡ ‰ÓÔÓÎÌËÚÂθÌ˚ı ÛÒÎÓ‚Ëfl:ÎÓ͇θ̇fl ÍÓÏÔ‡ÍÚÌÓÒÚ¸ ÔÓÒÚ‡ÌÒÚ‚‡ (˝ÚËÏ Ó·ÂÒÔ˜˂‡ÂÚÒfl ÎÓ͇θÌÓ ÒÛ˘ÂÒÚ‚Ó‚‡ÌË „ÂÓ‰ÂÁ˘ÂÒÍËı) Ë ÎÓ͇θÌÓ ‡Ò¯ËÂÌË „ÂÓ‰ÂÁ˘ÂÒÍËı.
ÖÒÎË ÔË ˝ÚÓÏk = k', ÚÓ ÔÓÒÚ‡ÌÒÚ‚Ó fl‚ÎflÂÚÒfl ËχÌÓ‚˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏ Ò ÔÓÒÚÓflÌÌÓÈÍË‚ËÁÌÓÈ k (ÒÏ. èÓÒÚ‡ÌÒÚ‚Ó „ÂÓ‰ÂÁ˘ÂÒÍËı, „Î. 6).δ (Tn )èÓÒÚ‡ÌÒÚ‚Ó ÍË‚ËÁÌ˚ ≤ k ÓÔ‰ÂÎflÂÚÒfl ÛÒÎÓ‚ËÂÏ lim≤ k. Ç Ú‡ÍÓÏσ(Tn0 )ÔÓÒÚ‡ÌÒڂ β·‡fl ÚӘ͇ ËÏÂÂÚ ÌÂÍÓÚÓÛ˛ ÓÍÂÒÚÌÓÒÚ¸, ‚ ÍÓÚÓÓÈ ÒÛÏχα + β + γ Û„ÎÓ‚ „ÂÓ‰ÂÁ˘ÂÒÍÓ„Ó ÚÂÛ„ÓθÌË͇ í Ì Ô‚˚¯‡ÂÚ ÒÛÏÏÛ α k + β k + γ kÛ„ÎÓ‚ ÚÂÛ„ÓθÌË͇ Tk ÒÓ ÒÚÓÓ̇ÏË ÚÓÈ Ê ‰ÎËÌ˚ ‚ ÔÓÒÚ‡ÌÒÚ‚Â ÔÓÒÚÓflÌÌÓÈ ÍË‚ËÁÌ˚ k. ÇÌÛÚÂÌÌflfl ÏÂÚË͇ Ú‡ÍÓ„Ó ÔÓÒÚ‡ÌÒÚ‚‡ ̇Á˚‚‡ÂÚÒfl k-‚Ó„ÌÛÚÓÈ ÏÂÚËÍÓÈ.δ (Tn )èÓÒÚ‡ÌÒÚ‚Ó ÍË‚ËÁÌ˚ ≥ k ÓÔ‰ÂÎflÂÚÒfl ÛÒÎÓ‚ËÂÏ lim≤ k.
Ç Ú‡ÍÓÏσ(Tn0 )ÔÓÒÚ‡ÌÒڂ β·‡fl ÚӘ͇ ËÏÂÂÚ ÌÂÍÓÚÓÛ˛ ÓÍÂÒÚÌÓÒÚ¸, ‚ ÍÓÚÓÓÈα + β + γ ≥ α k + β k + γ k ‰Îfl ÚÂÛ„ÓθÌËÍÓ‚ í Ë T k. ÇÌÛÚÂÌÌ˛˛ ÏÂÚËÍÛ Ú‡ÍÓ„ÓÔÓÒÚ‡ÌÒÚ‚‡ ̇Á˚‚‡˛Ú K-‚Ó„ÌÛÚÓÈ ÏÂÚËÍÓÈ.èÓÒÚ‡ÌÒÚ‚Ó ÄÎÂÍ҇̉ӂ‡ fl‚ÎflÂÚÒfl Ó·Ó·˘ÂÌÌ˚Ï ËχÌÓ‚˚Ï ÔÓÒÚ‡ÌÒÚ‚ÓÏÒ Ó„‡Ì˘ÂÌÌÓÈ ‚ÂıÌÂÈ, ÌËÊÌÂÈ ËÎË ËÌÚ„‡Î¸ÌÓÈ ÍË‚ËÁÌÓÈ.É·‚‡ 7. êËχÌÓ‚˚ Ë ùÏËÚÓ‚˚ ÏÂÚËÍË119èÓÎ̇fl ËχÌÓ‚‡ ÏÂÚË͇êËχÌÓ‚‡ ÏÂÚË͇ g ̇ ÏÌÓ„ÓÓ·‡ÁËË Mn ̇Á˚‚‡ÂÚÒfl ÔÓÎÌÓÈ, ÂÒÎË M n Ó·‡ÁÛÂÚÔÓÎÌÓ ÏÂÚ˘ÂÒÍÓ ÔÓÒÚ‡ÌÒÚ‚Ó ÔÓ ÓÚÌÓ¯ÂÌ˲ Í g.
ã˛·‡fl ËχÌÓ‚‡ ÏÂÚË͇ ̇ÍÓÏÔ‡ÍÚÌÓÏ ÏÌÓ„ÓÓ·‡ÁËË fl‚ÎflÂÚÒfl ÔÓÎÌÓÈ.ê˘˜Ë-ÔÎÓÒ͇fl ÏÂÚË͇ê˘˜Ë-ÔÎÓÒÍÓÈ ÏÂÚËÍÓÈ Ì‡Á˚‚‡ÂÚÒfl ËχÌÓ‚‡ ÏÂÚË͇, ÚÂÌÁÓ ÍË‚ËÁÌ˚ÍÓÚÓÓÈ Ó·‡˘‡ÂÚÒfl ‚ ÌÛθ.èÎÓÒÍÓ ÏÌÓ„ÓÓ·‡ÁË ê˘˜Ë Ô‰ÒÚ‡‚ÎflÂÚ ÒÓ·ÓÈ ËχÌÓ‚Ó ÏÌÓ„ÓÓ·‡ÁËÂ, Ò̇·ÊÂÌÌÓ ê˘˜Ë-ÔÎÓÒÍÓÈ ÏÂÚËÍÓÈ. èÎÓÒÍË ÏÌÓ„ÓÓ·‡ÁËfl ê˘˜Ë fl‚Îfl˛ÚÒfl ‚‡ÍÛÛÏÌ˚Ï Â¯ÂÌËÂÏ Â‚ÍÎˉӂ‡ ı‡‡ÍÚÂËÒÚ˘ÂÒÍÓ„Ó ÔÓÎËÌÓχ Ë ÓÒÓ·˚ÏË ÒÎÛ˜‡flÏË ÏÌÓ„ÓÓ·‡ÁËÈ äÂı·–ùÈ̯ÚÂÈ̇. ä ‚‡ÊÌ˚Ï ÔÎÓÒÍËÏ ÏÌÓ„ÓÓ·‡ÁËflÏ ê˘˜Ë ÓÚÌÓÒflÚÒfl ÏÌÓ„ÓÓ·‡ÁËfl ä‡Î‡·Ë–üÛ Ë „ËÔÂÏÌÓ„ÓÓ·‡ÁËfläÂı·.åÂÚË͇ éÒÒÂχ̇åÂÚËÍÓÈ éÒÒÂχ̇ ̇Á˚‚‡ÂÚÒfl ËχÌÓ‚‡ ÏÂÚË͇, ‰Îfl ÍÓÚÓÓÈ ËχÌÓ‚ÚÂÌÁÓ ÍË‚ËÁÌ˚ R fl‚ÎflÂÚÒfl ÓÒÒÂχÌÓ‚˚Ï. ùÚÓ ÓÁ̇˜‡ÂÚ, ˜ÚÓ ÒÓ·ÒÚ‚ÂÌÌ˚ Á̇˜ÂÌËfl ÓÔ‡ÚÓ‡ üÍÓ·Ë ( x ) : y → R( y, x ) x ̇ ‰ËÌ˘ÌÓÈ ÒÙ Sn–1 ÔÓÒÚ‡ÌÒÚ‚‡ n ·Û‰ÛÚ ÔÓÒÚÓflÌÌ˚ÏË, Ú.Â. ÌÂÁ‡‚ËÒËÏ˚ÏË ÓÚ Â‰ËÌ˘Ì˚ı ‚ÂÍÚÓÓ‚ ı.G-ËÌ‚‡Ë‡ÌÚ̇fl ÏÂÚË͇G-ËÌ‚‡Ë‡ÌÚÌÓÈ ÏÂÚËÍÓÈ Ì‡Á˚‚‡ÂÚÒfl ËχÌÓ‚‡ ÏÂÚË͇ g ̇ ‰ËÙÙÂÂ̈ËÛÂÏÓÏ ÏÌÓ„ÓÓ·‡ÁËË Mn , ÍÓÚÓ‡fl Ì ËÁÏÂÌflÂÚÒfl ÔË Î˛·˚ı ÔÂÓ·‡ÁÓ‚‡ÌËflı‰‡ÌÌÓÈ „ÛÔÔ˚ ãË (G, ⋅ , id ).
ÉÛÔÔ‡ (G, ⋅ , id ) ̇Á˚‚‡ÂÚÒfl „ÛÔÔÓÈ ‰‚ËÊÂÌËÈ (ËÎË„ÛÔÔÓÈ ËÁÓÏÂÚËÈ) ËχÌÓ‚‡ ÔÓÒÚ‡ÌÒÚ‚‡ (Mn , g).åÂÚË͇ à‚‡ÌÓ‚‡–èÂÚÓ‚ÓÈèÛÒÚ¸ R – ËχÌÓ‚˚Ï ÚÂÌÁÓÓÏ ÍË‚ËÁÌ˚ ËχÌÓ‚‡ ÏÌÓ„ÓÓ·‡ÁËfl Mn Ë {x, y} –ÓÚÓ„Ó̇θÌ˚È ·‡ÁËÒ ÓËÂÌÚËÓ‚‡ÌÌÓÈ 2-ÔÎÓÒÍÓÒÚË π ‚ Í‡Ò‡ÚÂθÌÓÏ ÔÓÒÚ‡ÌÒÚ‚ÂT p (M n ).åÂÚËÍÓÈ à‚‡ÌÓ‚‡–èÂÚÓ‚ÓÈ Ì‡Á˚‚‡ÂÚÒfl ËχÌÓ‚‡ ÏÂÚË͇ ̇ Mn , ‰Îfl ÍÓÚÓÓÈÒÓ·ÒÚ‚ÂÌÌ˚ Á̇˜ÂÌËfl ‡ÌÚËÒËÏÏÂÚ˘ÌÓ„Ó ÓÔ‡ÚÓ‡ ÍË‚ËÁÌ˚ ( π) = R( x, y)([IvSt95]) Á‡‚ËÒflÚ ÚÓθÍÓ ÓÚ ÚÓ˜ÍË ËχÌÓ‚‡ ÏÌÓ„ÓÓ·‡ÁËfl Mn , ÌÓ Ì ÓÚ ÔÎÓÒÍÓÒÚË π.åÂÚË͇ áÓηåÂÚËÍÓÈ áÓη ̇Á˚‚‡ÂÚÒfl ËχÌÓ‚‡ ÏÂÚË͇ ̇ „·‰ÍÓÏ ÏÌÓ„ÓÓ·‡ÁËË Mn ,„ÂÓ‰ÂÁ˘ÂÒÍË ÍÓÚÓÓ„Ó fl‚Îfl˛ÚÒfl ÔÓÒÚ˚ÏË Á‡ÏÍÌÛÚ˚ÏË ÍË‚˚ÏË ‡‚ÌÓȉÎËÌ˚.
Ñ‚ÛÏÂ̇fl ÒÙ‡ S2 ‰ÓÔÛÒ͇ÂÚ ÏÌÓÊÂÒÚ‚Ó Ú‡ÍËı ÏÂÚËÍ, ÔÓÏËÏÓ Ó˜Â‚Ë‰Ì˚ı ÏÂÚËÍ ÔÓÒÚÓflÌÌÓÈ ÍË‚ËÁÌ˚. Ç ÚÂÏË̇ı ˆËÎË̉˘ÂÒÍËı ÍÓÓ‰Ë̇Ú( z, θ) ( z ∈[ −1, 1], θ ∈[0, 2 π]) ÎËÌÂÈÌ˚È ˝ÎÂÏÂÌÚds 2 =(1 + f ( z ))2 2dz + (1 − z 2 )dθ 21 − z2Á‡‰‡ÂÚ ÏÂÚËÍÛ áÓη ̇ ÒÙ S2 ‰Îfl β·ÓÈ „·‰ÍÓÈ Ì˜ÂÚÌÓÈ ÙÛÌ͈ËËf : [ −1, 1] → ( −1, 1), ÍÓÚÓ‡fl Ó·‡˘‡ÂÚÒfl ‚ ÌÛθ ‚ ÍÓ̈‚˚ı ÚӘ͇ı ËÌÚ‚‡Î‡.120ó‡ÒÚ¸ II. ÉÂÓÏÂÚËfl ‡ÒÒÚÓflÌËflñËÍÎÓˉ‡Î¸Ì‡fl ÏÂÚË͇ñËÍÎÓˉ‡Î¸Ì‡fl ÏÂÚË͇ – ˝ÚÓ ËχÌÓ‚‡ ÏÂÚË͇2 + = {x ∈ 2 : x1 ≥ 0}, Á‡‰‡‚‡Âχfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 =̇ÔÓÎÛÔÎÓÒÍÓÒÚËdx12 + dx 22.2 x1é̇ ̇Á˚‚‡ÂÚÒfl ˆËÍÎÓˉ‡Î¸ÌÓÈ, ÔÓÒÍÓθÍÛ Â „ÂÓ‰ÂÁ˘ÂÒÍË fl‚Îfl˛ÚÒfl ˆËÍÎÓˉ‡Î¸Ì˚ÏË ÍË‚˚ÏË.
ëÓÓÚ‚ÂÚÒÚ‚Û˛˘Â ‡ÒÒÚÓflÌË d(x, y) ÏÂÊ‰Û ‰‚ÛÏfl ÚӘ͇ÏËx, y ∈ 2+ ˝Í‚Ë‚‡ÎÂÌÚÌÓ ‡ÒÒÚÓflÌ˲ρ( x, y) =| x1 − y1 | + | x 2 − y2 |x1 + x 2 + | x 2 − y2‚ ÚÓÏ ÒÏ˚ÒÎÂ, ˜ÚÓ d ≤ Cρ Ë ρ ≤ Cd ‰Îfl ÌÂÍÓÂÈ ÔÓÎÓÊËÚÂθÌÓÈ ÍÓÌÒÚ‡ÌÚ˚ ë.åÂÚË͇ Å„‡åÂÚËÍÓÈ Å„‡ ̇Á˚‚‡ÂÚÒfl ËχÌÓ‚‡ ÏÂÚË͇ ̇ ÒÙ ń‡ (Ú.Â. ÒʇÚÓÈ‚ Ó‰ÌÓÏ Ì‡Ô‡‚ÎÂÌËË ÒÙ S3 ), Á‡‰‡‚‡Âχfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 = dθ 2 + sin 2 θd φ 2 + cos 2 α( dψ + cos θd φ)2 ,„‰Â α – ÍÓÌÒÚ‡ÌÚ‡, ‡ θ, φ, ψ – Û„Î˚ ùÈ·.åÂÚË͇ ä‡ÌÓ-䇇ÚÂÓ‰ÓËê‡ÒÔ‰ÂÎÂÌË (ËÎË ÔÓÎflËÁ‡ˆËfl) ̇ M n ÂÒÚ¸ ÔÓ‰‡ÒÒÎÓÂÌË ͇҇ÚÂθÌÓ„Ó‡ÒÒÎÓÂÌËfl T(M n ) ÏÌÓ„ÓÓ·‡ÁËfl Mn .
èË Ì‡Î˘ËË ÔÓÎflËÁ‡ˆËË H(M n ) ‚ÂÍÚÓÌÓÂÔÓΠ‚ H(Mn ) ̇Á˚‚‡ÂÚÒfl „ÓËÁÓÌڇθÌ˚Ï. äË‚‡fl γ ̇ M n ̇Á˚‚‡ÂÚÒfl„ÓËÁÓÌڇθÌÓÈ (ËÎË ‚˚‰ÂÎÂÌÌÓÈ, ‰ÓÔÛÒÚËÏÓÈ) ÔÓ ÓÚÌÓ¯ÂÌ˲ Í H(Mn ), ÂÒÎË γ ′(t ) ∈ Hγ ( t ) ( M n )‰Îfl β·Ó„Ó t. ê‡ÒÔ‰ÂÎÂÌË H(M n ) ̇Á˚‚‡ÂÚÒfl ‡·ÒÓβÚÌÓ ÌÂËÌÚ„ËÛÂÏ˚Ï, ÂÒÎËÒÍÓ·ÍË ãË [...,[ H ( M n ), H ( M n )]] ÔÓÎflËÁ‡ˆËË H(M n ) ÔÂÂÍ˚‚‡˛Ú ͇҇ÚÂθÌÓ‡ÒÒÎÓÂÌË T(M n ), Ú.Â. ‰Îfl ‚ÒÂı p ∈ Mn β·ÓÈ Í‡Ò‡ÚÂθÌ˚È ‚ÂÍÚÓ v ËÁ T p (M n ) ÏÓÊÂÚ·˚Ú¸ Ô‰ÒÚ‡‚ÎÂÌ Í‡Í ÎËÌÂÈ̇fl ÍÓÏ·Ë̇ˆËfl ‚ÂÍÚÓÓ‚ ÒÎÂ‰Û˛˘Ëı ‚ˉӂ: u, [u, w],[u, [w, t]], [u, [w, [t, s]]],... ∈ Tp(M n ), „‰Â ‚Ò ‚ÂÍÚÓÌ˚ ÔÓÎfl u, w, t, s,... fl‚Îfl˛ÚÒfl„ÓËÁÓÌڇθÌ˚ÏË.åÂÚËÍÓÈ ä‡ÌӖ䇇ÚÂÓ‰ÓË (ËÎË ë–ë ÏÂÚËÍÓÈ) ̇Á˚‚‡ÂÚÒfl ÏÂÚË͇ ̇ÏÌÓ„ÓÓ·‡ÁËË Mn Ò ‡·ÒÓβÚÌÓ ÌÂËÌÚ„ËÛÂÏ˚Ï „ÓËÁÓÌڇθÌ˚Ï ‡ÒÔ‰ÂÎÂÌËÂÏH(Mn ), Á‡‰‡‚‡Âχfl ̇·ÓÓÏ gc ÔÓÎÓÊËÚÂθÌÓ ÓÔ‰ÂÎÂÌÌ˚ı Ò͇ÎflÌ˚ı ÔÓËÁ‚‰ÂÌËÈ Ì‡ H (Mn ).
ê‡ÒÒÚÓflÌË dc(p, q) ÏÂÊ‰Û Î˛·˚ÏË ÚӘ͇ÏË p, q ∈ M n ÓÔ‰ÂÎflÂÚÒfl Í‡Í ËÌÙËÏÛÏ gc-‰ÎËÌ „ÓËÁÓÌڇθÌ˚ı ÍË‚˚ı, ÒÓ‰ËÌfl˛˘Ëı ÚÓ˜ÍË p Ë q.èÓ‰ËχÌÓ‚˚Ï ÏÌÓ„ÓÓ·‡ÁËÂÏ (ËÎË ÔÓÎflËÁÓ‚‡ÌÌ˚Ï ÏÌÓ„ÓÓ·‡ÁËÂÏ) ̇Á˚‚‡ÂÚÒfl ÏÌÓ„ÓÓ·‡ÁË Mn , Ò̇·ÊÂÌÌÓ ÏÂÚËÍÓÈ ä‡ÌӖ䇇ÚÂÓ‰ÓË. éÌÓ fl‚ÎflÂÚÒflÓ·Ó·˘ÂÌËÂÏ ËχÌÓ‚‡ ÏÌÓ„ÓÓ·‡ÁËfl. ÉÛ·Ó „Ó‚Ófl, ‰Îfl ËÁÏÂÂÌËfl ‡ÒÒÚÓflÌËÈ ‚ÔÓ‰ËχÌÓ‚ÓÏ ÏÌÓ„ÓÓ·‡ÁËË ÏÓÊÌÓ ÒΉӂ‡Ú¸ ÚÓθÍÓ ‚‰Óθ ÍË‚˚ı, fl‚Îfl˛˘ËıÒfl͇҇ÚÂθÌ˚ÏË Í „ÓËÁÓÌڇθÌ˚Ï ÔÓÒÚ‡ÌÒÚ‚‡Ï.èÒ‚‰ÓËχÌÓ‚‡ ÏÂÚË͇ê‡ÒÒÏÓÚËÏ ‰ÂÈÒÚ‚ËÚÂθÌÓ n-ÏÂÌÓ ‰ËÙÙÂÂ̈ËÛÂÏÓ ÏÌÓ„ÓÓ·‡ÁË Mn , ‚ÍÓÚÓÓÏ Í‡Ê‰Ó ͇҇ÚÂθÌÓ ÔÓÒÚ‡ÌÒÚ‚Ó Tp(M n ), p ∈ Mn Ò̇·ÊÂÌÓ „·‰ÍÓ ËÁÏÂ-121É·‚‡ 7. êËχÌÓ‚˚ Ë ùÏËÚÓ‚˚ ÏÂÚËÍËÌfl˛˘ËÏÒfl ÓÚ ÚÓ˜ÍË Í ÚӘ͠Ò͇ÎflÌ˚Ï ÔÓËÁ‚‰ÂÌËÂÏ, ÍÓÚÓÓ fl‚ÎflÂÚÒflÌ‚˚ÓʉÂÌÌ˚Ï, ÌÓ ÌÂÓÔ‰ÂÎÂÌÌ˚Ï.èÒ‚‰ÓËχÌÓ‚ÓÈ ÏÂÚËÍÓÈ Ì‡ M n ̇Á˚‚‡ÂÚÒfl ÒÓ‚ÓÍÛÔÌÓÒÚ¸ Ò͇ÎflÌ˚ı ÔÓËÁ‚‰ÂÌËÈ 〈 , 〉 p ̇ ͇҇ÚÂθÌ˚ı ÔÓÒÚ‡ÌÒÚ‚‡ı Tp (M n ), p ∈ Mn , ÔÓ Ó‰ÌÓÏÛ ‰Îfl ͇ʉÓÈÚÓ˜ÍË p ∈ Mn .ä‡Ê‰Ó Ò͇ÎflÌÓ ÔÓËÁ‚‰ÂÌË 〈 , 〉 p ÔÓÎÌÓÒÚ¸˛ ÓÔ‰ÂÎÂÌÓ Ò͇ÎflÌ˚ÏË ÔÓËÁ‚‰ÂÌËflÏË 〈ei , e j 〉 p = gij ( p) ˝ÎÂÏÂÌÚÓ‚ e1 ,..., en Òڇ̉‡ÚÌÓ„Ó ·‡ÁËÒ‡ ‚ n, Ú.Â.‰ÂÈÒÚ‚ËÚÂθÌÓÈ ÒËÏÏÂÚ˘ÌÓÈ ÌÂÓÔ‰ÂÎÂÌÌÓÈ n × n χÚˈÂÈ (( gij )) = (( gij ( p))),̇Á˚‚‡ÂÏÓÈ ÏÂÚ˘ÂÒÍËÏ ÚÂÌÁÓÓÏ (ÒÏ.
êËχÌÓ‚‡ ÏÂÚË͇, „‰Â ÏÂÚ˘ÂÒÍËÈÚÂÌÁÓ fl‚ÎflÂÚÒfl ‰ÂÈÒÚ‚ËÚÂθÌÓÈ ÒËÏÏÂÚ˘ÌÓÈ ÔÓÎÓÊËÚÂθÌÓ ÓÔ‰ÂÎÂÌÌÓÈ n × nχÚˈÂÈ). àÏÂÌÌÓ, 〈 x, y 〉 p =gij ( p) xi y j , „‰Â x = ( x1 ,..., x n ) Ë y = ( y1 ,..., yn ) ∈∑i, j∈Tp ( M ). É·‰Í‡fl ÙÛÌ͈Ëfl g ÔÓÎÌÓÒÚ¸˛ ÓÔ‰ÂÎflÂÚ ÔÒ‚‰ÓËχÌÓ‚Û ÏÂÚËÍÛ.ÑÎË̇ ds ‚ÂÍÚÓ‡ ( dx1 ,..., dx n ) ‚˚‡Ê‡ÂÚÒfl Í‚‡‰‡Ú˘ÂÒÍÓÈ ‰ËÙÙÂÂ̈ˇθÌÓÈÙÓÏÓÈnds 2 =∑ gij dxi dx j .i, jÑÎË̇ÍË‚ÓÈγ : [0, 1] → M n‚˚‡Ê‡ÂÚÒflÙÓÏÛÎÓÈgij dxi dx j =∫ ∑i, jγ1=gij∫ ∑i, j0dxi dx jdt. Ç Ó·˘ÂÏ ÒÎÛ˜‡Â Ó̇ ÏÓÊÂÚ ·˚Ú¸ ‰ÂÈÒÚ‚ËÚÂθÌÓÈ, ˜ËÒÚÓdt dtÏÌËÏÓÈ ËÎË ÌÛ΂ÓÈ (ËÁÓÚÓÔ̇fl ÍË‚‡fl).èÒ‚‰ÓËχÌÓ‚‡ ÏÂÚË͇ ̇ M n fl‚ÎflÂÚÒfl ÏÂÚËÍÓÈ Ò ÙËÍÒËÓ‚‡ÌÌÓÈ, ÌÓ ÌÂÓÔ‰ÂÎÂÌÌÓÈ Ò˄̇ÚÛÓÈ (p, q), p + q = n.
èÒ‚‰ÓËχÌÓ‚‡ ÏÂÚË͇ fl‚ÎflÂÚÒflÌ‚˚ÓʉÂÌÌÓÈ, Ú.Â.  ÏÂÚ˘ÂÒÍËÈ ÓÔ‰ÂÎËÚÂθ det(( gij )) ≠ 0. èÓ˝ÚÓÏÛ Ó̇fl‚ÎflÂÚÒfl Ì‚˚ÓʉÂÌÌÓÈ ÌÂÓÔ‰ÂÎÂÌÌÓÈ ÏÂÚËÍÓÈ.èÒ‚‰ÓËχÌÓ‚Ó ÏÌÓ„ÓÓ·‡ÁË (ËÎË ÔÒ‚‰ÓËχÌÓ‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó) – ‰ÂÈÒÚ‚ËÚÂθÌÓ n-ÏÂÌÓ ‰ËÙÙÂÂ̈ËÛÂÏÓ ÏÌÓ„ÓÓ·‡ÁË Mn , Ò̇·ÊÂÌÌÓ ÔÒ‚‰ÓËχÌÓ‚ÓÈ ÏÂÚËÍÓÈ. íÂÓËfl ÔÒ‚‰ÓËχÌÓ˚ı ÔÓÒÚ‡ÌÒÚ‚ ̇Á˚‚‡ÂÚÒfl ÔÒ‚‰ÓËχÌÓ‚ÓÈ „ÂÓÏÂÚËÂÈ.åÓ‰Âθ˛ ÔÒ‚‰ÓËχÌÓ‚‡ ÔÓÒÚ‡ÌÒÚ‚‡ Ò Ò˄̇ÚÛÓÈ (p, q) fl‚ÎflÂÚÒfl ÔÒ‚‰Ó‚ÍÎË‰Ó‚Ó ÔÓÒÚ‡ÌÒÚ‚Ó p, q , p + q = n – ‰ÂÈÒÚ‚ËÚÂθÌÓ n-ÏÂÌÓ ‚ÂÍÚÓÌÓÂÔÓÒÚ‡ÌÒÚ‚Ó n, Ò̇·ÊÂÌÌÓ ÏÂÚ˘ÂÒÍËÏ ÚÂÌÁÓÓÏ ((g ij)) Ò Ò˄̇ÚÛÓÈ (p, q),Á‡‰‡ÌÌ˚Ï Í‡Í g11 = ...
= g pp = 1, g p +1, p +1 = ... = gnn = −1, gij = 0 ‰Îfl i ≠ j. ãËÌÂÈÌ˚È˝ÎÂÏÂÌÚ ÒÓÓÚ‚ÂÚÒÚ‚Û˛˘ÂÈ ÏÂÚËÍË Á‡‰‡ÂÚÒfl ͇Íds 2 = dx12 + ... + dx 2p − dx 2p +1 − ... − dx n2 .ãÓÂ̈‚‡ ÏÂÚË͇ãÓÂ̈‚‡ ÏÂÚË͇ (ËÎË ÏÂÚË͇ ãÓÂ̈‡) – ÔÒ‚‰ÓËχÌÓ‚‡ ÏÂÚË͇ Ò Ò˄̇ÚÛÓÈ (1, p).ãÓÂ̈‚˚Ï ÏÌÓ„ÓÓ·‡ÁËÂÏ Ì‡Á˚‚‡ÂÚÒfl ÏÌÓ„ÓÓ·‡ÁËÂ, Ò̇·ÊÂÌÌÓ ÎÓÂ̈‚ÓÈÏÂÚËÍÓÈ.