Е. Деза_ М.М. Деза. Энциклопедический словарь расстояний (2008) (1185330), страница 35
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í‡ÍËÏ Ó·‡ÁÓÏ, ͇ʉÓÏÛ ÎÓ͇θÌÓÏÛ Ô‡‡ÏÂÚÛ z ( z : U → ) ÒÚ‡‚ËÚÒfl ‚É·‚‡ 8. ê‡ÒÒÚÓflÌËfl ̇ ÔÓ‚ÂıÌÓÒÚflı Ë ÛÁ·ı 151ÒÓÓÚ‚ÂÚÒÚ‚Ë ÙÛÌ͈Ëfl Qz : (U ) → ڇ͇fl, ˜ÚÓ ‰Îfl β·˚ı ÎÓ͇θÌ˚ı Ô‡‡ÏÂÚÓ‚z1 Ë z2 ËÏÂÂÏ dz ( p ) = 1 Qz1 ( z1 ( p)) dz 2 ( p) Qz 2 ( z 2 ( p))2‰Îfl β·˚ı p ∈U1 ∩ U2 .ùÍÒÚÂχθ̇fl ÏÂÚË͇ùÍÒÚÂχθÌÓÈ ÏÂÚËÍÓÈ Ì‡Á˚‚‡ÂÚÒfl ÍÓÌÙÓÏÌÓ ËÌ‚‡Ë‡ÌÚ̇fl ÏÂÚË͇ ‚ Á‡‰‡˜Â ÏÓ‰ÛÎ˛Ò‡ ‰Îfl ÒÂÏÂÈÒÚ‚‡ Γ ÎÓ͇θÌÓ ÒÔflÏÎflÂÏ˚ı ÍË‚˚ı ̇ ËχÌÓ‚ÓÈÔÓ‚ÂıÌÓÒÚË R, ÍÓÚÓ‡fl ‡ÎËÁÛÂÚ ËÌÙËÏÛÏ ‚ ÓÔ‰ÂÎÂÌËË ÏÓ‰ÛÎ˛Ò‡ å(Γ).îÓχθÌÓ, ÔÛÒÚ¸ Γ – ÒÂÏÂÈÒÚ‚Ó ÎÓ͇θÌÓ ÒÔflÏÎflÂÏ˚ı ÍË‚˚ı ̇ ËχÌÓ‚ÓÈÔÓ‚ÂıÌÓÒÚË R Ë ÔÛÒÚ¸ ê – ÌÂÔÛÒÚÓÈ Í·ÒÒ ÍÓÌÙÓÏÌÓ ËÌ‚‡Ë‡ÌÚÌ˚ı ÏÂÚËÍρ( z ) dz ̇ R, Ú‡ÍËı ˜ÚÓ ρ(z) fl‚ÎflÂÚÒfl Í‚‡‰‡Ú˘ÌÓ ËÌÚ„ËÛÂÏÓÈ ‚ z-ÔÎÓÒÍÓÒÚË ‰ÎflÍ‡Ê‰Ó„Ó ÎÓ͇θÌÓ„Ó Ô‡‡ÏÂÚ‡ z, ‡ ËÌÚ„‡Î˚Aρ ( R) =∫ ∫ ρ (z )dxdy2∫Ë Lρ (Γ ) = inf ρ( z ) dzγ ∈ΓRyÌ fl‚Îfl˛ÚÒfl Ó‰ÌÓ‚ÂÏÂÌÌÓ ‡‚Ì˚ÏË 0 ËÎË ∞ (ÔÓ‰‡ÁÛÏ‚‡ÂÚÒfl, ˜ÚÓ Í‡Ê‰˚È ËÁ‚˚¯ÂÔ˂‰ÂÌÌ˚ı ËÌÚ„‡ÎÓ‚ – ˝ÚÓ ËÌÚ„‡Î ã·„‡).
åÓ‰ÛÎ˛Ò ÒÂÏÂÈÒÚ‚‡ ÍË‚˚ıΓ ÓÔ‰ÂÎflÂÚÒfl ͇ÍM (Γ ) = infρ ∈PAρ ( R)( Lρ (Γ ))2.ùÍÒÚÂχθ̇fl ‰ÎË̇ ÒÂÏÂÈÒÚ‚‡ ÍË‚˚ı Γ ‡‚̇ supρ ∈P( Lρ (U ))2Aρ ( R), Ú.Â. fl‚ÎflÂÚÒfl‚Â΢ËÌÓÈ, Ó·‡ÚÌÓÈ å(Γ).ᇉ‡˜‡ ÏÓ‰ÛÎ˛Ò‡ ‰Îfl Γ ÓÔ‰ÂÎflÂÚÒfl ÒÎÂ‰Û˛˘ËÏ Ó·‡ÁÓÏ: ÔÛÒÚ¸ PL – ÔӉͷÒÒ/ ÖÒÎË , ÚÓ ÏÓ‰ÛP, Ú‡ÍÓÈ ˜ÚÓ ‰Îfl β·˚ı ρ ∈ ( z ) dz ∈ PL Ë Î˛·ÓÈ γ ∈ Γ ËÏÂÂÏ PL ≠ 0,Î˛Ò å(Γ) ÒÂÏÂÈÒÚ‚‡ Γ ÏÓÊÂÚ ·˚Ú¸ Á‡ÔËÒ‡Ì Í‡Í M (Γ ) = inf Aρ ( R). ä‡Ê‰‡fl ÏÂÚË͇ρ ∈PLËÁ PL ̇Á˚‚‡ÂÚÒfl ‰ÓÔÛÒÚËÏÓÈ ÏÂÚËÍÓÈ ‰Îfl Á‡‰‡˜Ë ÏÓ‰ÛÎ˛Ò‡ ̇ Γ. ÖÒÎË ÒÛ˘ÂÒÚ‚ÛÂÚρ*, ‰Îfl ÍÓÚÓÓÈM (Γ ) = inf Aρ ( R) = Aρ* ( R),ρ ∈PLÏÂÚË͇ ρ* dz ̇Á˚‚‡ÂÚÒfl ˝ÍÒÚÂχθÌÓÈ ÏÂÚËÍÓÈ ‰Îfl Á‡‰‡˜Ë ÏÓ‰ÛÎ˛Ò‡ ̇ Γ.åÂÚË͇ ÔÓ‚ÂıÌÓÒÚË î¯ÂèÛÒÚ¸ (X, d) – ÔÓËÁ‚ÓθÌÓ ÏÂÚ˘ÂÒÍÓ ÔÓÒÚ‡ÌÒÚ‚Ó, å2 – ÍÓÏÔ‡ÍÚÌÓ ‰‚ÛÏÂÌÓ ÏÌÓ„ÓÓ·‡ÁËÂ, f – ÌÂÔÂ˚‚ÌÓ ÓÚÓ·‡ÊÂÌË f: M 2 → X, ̇Á˚‚‡ÂÏÓÂÔ‡‡ÏÂÚËÁÓ‚‡ÌÌÓÈ ÔÓ‚ÂıÌÓÒÚ¸˛, ‡ σ: M 2 → M2 – „ÓÏÂÓÏÓÙËÁÏ M2 ̇ Ò·fl.т ԇ‡ÏÂÚËÁËÓ‚‡ÌÌ˚ı ÔÓ‚ÂıÌÓÒÚË f1 Ë f2 ̇Á˚‚‡˛ÚÒfl ˝Í‚Ë‚‡ÎÂÌÚÌ˚ÏË, ÂÒÎËinf max d ( f1 ( p), f2 (σ( p)) = 0, „‰Â ËÌÙËÏÛÏ ·ÂÂÚÒfl ÔÓ ‚ÒÂÏ ‚ÓÁÏÓÊÌ˚Ï „ÓÏÂÓσ ρ ∈M 2ÏÓÙËÁÏ‡Ï σ .
ä·ÒÒ f* Ô‡‡ÏÂÚËÁËÓ‚‡ÌÌ˚ı ÔÓ‚ÂıÌÓÒÚÂÈ, ˝Í‚Ë‚‡ÎÂÌÚÌ˚ı f,152ó‡ÒÚ¸ II. ÉÂÓÏÂÚËfl ‡ÒÒÚÓflÌËfl̇Á˚‚‡ÂÚÒfl ÔÓ‚ÂıÌÓÒÚ¸˛ î¯Â. ùÚÓ fl‚ÎflÂÚÒfl Ó·Ó·˘ÂÌËÂÏ ÔÓÌflÚËfl ÔÓ‚ÂıÌÓÒÚË‚ ‚ÍÎˉӂÓÏ ÔÓÒÚ‡ÌÒÚ‚Â ‰Îfl ÒÎÛ˜‡fl ÔÓËÁ‚ÓθÌÓ„Ó ÏÂÚ˘ÂÒÍÓ„Ó ÔÓÒÚ‡ÌÒÚ‚‡(X, d).åÂÚËÍÓÈ ÔÓ‚ÂıÌÓÒÚË î¯ ̇Á˚‚‡ÂÚÒfl ÏÂÚË͇ ̇ ÏÌÓÊÂÒÚ‚Â ‚ÒÂı ÔÓ‚ÂıÌÓÒÚÂÈ î¯Â, ÓÔ‰ÂÎflÂχfl ͇Íinf max d ( f1 ( p), f2 (σ( p)))σ ρ ∈M 2‰Îfl β·˚ı ÔÓ‚ÂıÌÓÒÚÂÈ î¯ f1* Ë f2* , „‰Â ËÌÙËÏÛÏ ·ÂÂÚÒfl ÔÓ ‚ÒÂÏ ‚ÓÁÏÓÊÌ˚Ï „ÓÏÂÓÏÓÙËÁÏ‡Ï σ (ÒÏ. åÂÚË͇ î¯Â).8.2. ÇçìíêÖççàÖ åÖíêàäà çÄ èéÇÖêïçéëíüïÇ ‰‡ÌÌÓÏ ‡Á‰ÂΠÔ˜ËÒÎÂÌ˚ ‚ÌÛÚÂÌÌË ÏÂÚËÍË, ÓÔ‰ÂÎflÂÏ˚ Ëı ÎËÌÂÈÌ˚ÏË˝ÎÂÏÂÌÚ‡ÏË (ÍÓÚÓ˚ ‚ ‰ÂÈÒÚ‚ËÚÂθÌÓÒÚË, fl‚Îfl˛ÚÒfl ‰‚ÛÏÂÌ˚ÏË ËχÌÓ‚˚ÏËÏÂÚË͇ÏË) ‰Îfl ÌÂÍÓÚÓ˚ı ËÁ·‡ÌÌ˚ı ÔÓ‚ÂıÌÓÒÚÂÈ.åÂÚË͇ Í‚‡‰ËÍË䂇‰ËÍÓÈ (ËÎË Í‚‡‰‡Ú˘ÌÓÈ ÔÓ‚ÂıÌÓÒÚ¸˛, ÔÓ‚ÂıÌÓÒÚ¸˛ ‚ÚÓÓ„Ó ÔÓfl‰Í‡)̇Á˚‚‡ÂÚÒfl ÏÌÓÊÂÒÚ‚Ó ÚÓ˜ÂÍ ‚ 3, ÍÓÓ‰Ë̇Ú˚ ÍÓÚÓ˚ı ‚ ‰Â͇ÚÓ‚ÓÈ ÒËÒÚÂÏÂÍÓÓ‰ËÌ‡Ú Û‰Ó‚ÎÂÚ‚Ófl˛Ú ‡Î„·‡Ë˜ÂÒÍÓÏÛ Û‡‚ÌÂÌ˲ ‚ÚÓÓÈ ÒÚÂÔÂÌË.
ëÛ˘ÂÒÚ‚ÛÂÚ 17 Í·ÒÒÓ‚ Ú‡ÍËı ÔÓ‚ÂıÌÓÒÚÂÈ, ‚ ÚÓÏ ˜ËÒΠ˝ÎÎËÔÒÓˉ˚, Ó‰ÌÓÔÓÎÓÒÚÌ˚ ˉ‚ÛıÔÓÎÓÒÚÌ˚ „ËÔ·ÓÎÓˉ˚, ˝ÎÎËÔÚ˘ÂÒÍË ԇ‡·ÓÎÓˉ˚, „ËÔ·Ó΢ÂÒÍË ԇ‡·ÓÎÓˉ˚, ˝ÎÎËÔÚ˘ÂÒÍËÂ, „ËÔ·Ó΢ÂÒÍËÂ Ë Ô‡‡·Ó΢ÂÒÍË ˆËÎË̉˚ Ë ÍÓÌ˘ÂÒÍË ÔÓ‚ÂıÌÓÒÚË.ñËÎË̉, ̇ÔËÏÂ, ÏÓÊÂÚ ·˚Ú¸ ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏ Á‡‰‡Ì Ò ÔÓÏÓ˘¸˛ÒÎÂ‰Û˛˘Ëı Û‡‚ÌÂÌËÈ:x1 (u, v) = a cos v, x 2 (u, v) = a sin v, x3 (u, v) = u.ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÌÂÏ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 = du 2 + a 2 dv 2 .ùÎÎËÔÚ˘ÂÒÍËÈ ÍÓÌÛÒ (Ú.Â.
ÍÓÌÛÒ Ò ˝ÎÎËÔÚ˘ÂÒÍËÏ Ò˜ÂÌËÂÏ) ÓÔ‰ÂÎflÂÚÒfl ‚Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏ ÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË:x1 (u, v) = ah−uh−ucos v, x 2 (u, v) = bsin v, x3 (u, v) = u,hh„‰Â h – ‚˚ÒÓÚ‡, ‡ – ·Óθ¯‡fl ÔÓÎÛÓÒ¸ Ë b – χ·fl ÔÓÎÛÓÒ¸ ÍÓÌÛÒ‡. ÇÌÛÚÂÌÌflflÏÂÚË͇ ̇ ÍÓÌÛÒ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 =h 2 + a 2 cos 2 v + b 2 sin 2 v 2( a 2 − b 2 )(h − u) cos v sin vdu + sdudv +2hh2+(h − u)2 ( a 2 sin 2 v + b 2 cos 2 v) 2dv .h2åÂÚË͇ ÒÙÂ˚ëÙ‡ fl‚ÎflÂÚÒfl Í‚‡‰ËÍÓÈ, ÍÓÓ‰Ë̇Ú˚ ÍÓÚÓÓÈ ‚ ‰Â͇ÚÓ‚ÓÈ ÒËÒÚÂÏ ‚˚‡ÊÂÌ˚ Û‡‚ÌÂÌËÂÏ (x1 – a)2 + (x 2 – b)2 + (x 3 – c)2 = r2 , „‰Â ÚӘ͇ (a, b, c) – ˆÂÌÚ ÒÙÂ˚,‡ r > 0 –  ‡‰ËÛÒ. ëÙ‡ ‡‰ËÛÒ‡ r Ò ˆÂÌÚÓÏ ‚ ̇˜‡Î ÍÓÓ‰ËÌ‡Ú ÏÓÊÂÚ ·˚ڸɷ‚‡ 8.
ê‡ÒÒÚÓflÌËfl ̇ ÔÓ‚ÂıÌÓÒÚflı Ë ÛÁ·ı 153Á‡‰‡Ì‡ ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏ ÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË:x1 (θ, φ) = r sin θ cos φ, x 2 (θ, φ) = r sin θ sin φ, x3 (θ, φ) = r cos φ,„‰Â ‡ÁËÏÛڇθÌ˚È Û„ÓÎ φ ∈ [0, 2π] Ë ÔÓÎflÌ˚È Û„ÓÎ θ ∈ [0, π]. ÇÌÛÚÂÌÌflfl ÏÂÚË͇̇ ÒÙ (ËÏÂÌÌÓ, ‰‚ÛÏÂ̇fl ÒÙ¢ÂÒ͇fl ÏÂÚË͇) Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 = r 2 dθ + r 2 sin 2 θdφ 2 .ëÙ‡ ‡‰ËÛÒa r ËÏÂÂÚ ÔÓÒÚÓflÌÌÛ˛ ÔÓÎÓÊËÚÂθÌÛ˛ „‡ÛÒÒÓ‚Û ÍË‚ËÁÌÛ, ‡‚ÌÛ˛ r.åÂÚË͇ ˝ÎÎËÔÒÓˉ‡ùÎÎËÔÒÓˉ – Í‚‡‰Ë͇, Á‡‰‡Ì̇fl ‰Â͇ÚÓ‚˚Ï Û‡‚ÌÂÌËÂÏx12 x 22 x32++= 1, ËÎËa2 b2 c2ÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏÂ:x1 (θ, φ) = a cos φ sin θ, x 2 (θ, φ) = b sin φ sin θ, x3 (θ, φ) = c cos θ,„‰Â ‡ÁËÏÛڇθÌ˚È Û„ÓÎ φ ∈ [0, 2π] Ë ÔÓÎflÌ˚È Û„ÓÎ θ ∈ [0, π] ÇÌÛÚÂÌÌflfl ÏÂÚË͇̇ ˝ÎÎËÔÒÓˉ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 = (b 2 cos 2 φ + a 2 sin 2 φ)sin 2 θdφ 2 + (b 2 − a 2 ) cos φ sin φ cos θ sin θdθdφ ++ (( a 2 cos 2 φ + b 2 sin 2 φ) cos 2 θ + c 2 sin 2 θ)dθ 2 .åÂÚË͇ ÒÙÂÓˉ‡ëÙÂÓˉÓÏ Ì‡Á˚‚‡ÂÚÒfl ˝ÎÎËÔÒÓˉ Ò ‰‚ÛÏfl Ó‰Ë̇ÍÓ‚˚ÏË ÔÓ ‰ÎËÌ ÓÒflÏË.
éÌfl‚ÎflÂÚÒfl Ú‡ÍÊ ÔÓ‚ÂıÌÓÒÚ¸˛ ‚‡˘ÂÌËfl, Á‡‰‡ÌÌÓÈ ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏÂÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË:x1 (u, v) = a sin v cos u, x 2 (u, v) = a sin v sin u, x3 (u, v) = c cos v,„‰Â 0 ≤ u ≤ 2π Ë 0 ≤ v < π. ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÒÙÂÓˉ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï˝ÎÂÏÂÌÚÓÏ1ds 2 = a 2 sin 2 vdu 2 + a 2 + c 2 + ( a 2 − c 2 ) cos(2 v) dv 2 .2()åÂÚË͇ „ËÔ·ÓÎÓˉ‡ÉËÔ·ÓÎÓˉ – Í‚‡‰Ë͇, ÍÓÚÓ‡fl ÏÓÊÂÚ ·˚Ú¸ Ó‰ÌÓ- ËÎË ‰ÛıÔÓÎÓÒÚÌÓÈ. é‰ÌÓÔÓÎÓÒÚÌ˚Ï „ËÔ·ÓÎÓˉÓÏ Ì‡Á˚‚‡ÂÚÒfl Ó·‡ÁÛÂχfl ‚‡˘ÂÌËÂÏ „ËÔ·ÓÎ˚ ÓÚÌÓÒËÚÂθÌÓ ÔÂÔẨËÍÛÎfl‡, ‰ÂÎfl˘Â„Ó ÔÓÔÓÎ‡Ï ÎËÌ˲ ÏÂÊ‰Û ÙÓÍÛÒ‡ÏË, ‡ ‰‚ÛıÔÓÎÓÒÚÌÓÈ „ËÔ·ÓÎÓˉ – ˝ÚÓ ÔÓ‚ÂıÌÓÒÚ¸, Ó·‡ÁÛÂχfl ‚‡˘ÂÌËÂÏ „ËÔ·ÓÎ˚ÓÚÌÓÒËÚÂθÌÓ ÎËÌËË, ÒÓ‰ËÌfl˛˘ÂÈ ÙÓÍÛÒ˚.
é‰ÌÓÔÓÎÓÒÚÌÓÈ „ËÔ·ÓÎÓˉ, ÓËÂÌÚËx2 x2 x2Ó‚‡ÌÌ˚È ÔÓ ÓÒË ı3 , Á‡‰‡ÂÚÒfl ‰Â͇ÚÓ‚˚Ï Û‡‚ÌÂÌËÂÏ 12 + 22 − 32 = 1 ËÎË ÒÎÂ‰Û˛abc˘ËÏË Û‡‚ÌÂÌËflÏË ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏÂ:x1 (u, v) = a 1 + u 2 cos v, x 2 (u, v) = a 1 + u 2 sin v, x3 (u, v) = cu,„‰Â v ∈ [0,˝ÎÂÏÂÌÚÓÏ2π].
ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ „ËÔ·ÓÎÓˉ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ïa 2u 2 22 22ds 2 = c 2 + 2 du + a (u + 1)dv .u + 1154ó‡ÒÚ¸ II. ÉÂÓÏÂÚËfl ‡ÒÒÚÓflÌËflåÂÚË͇ ÔÓ‚ÂıÌÓÒÚË ‚‡˘ÂÌËflèÓ‚ÂıÌÓÒÚ¸˛ ‚‡˘ÂÌËfl ̇Á˚‚‡ÂÚÒfl ÔÓ‚ÂıÌÓÒÚ¸, Ó·‡ÁÛÂχfl ‚‡˘ÂÌËÂÏ ‰‚ÛÏÂÌÓÈ ÍË‚ÓÈ ÓÚÌÓÒËÚÂθÌÓ ÌÂÍÓÚÓÓÈ ÓÒË. Ö ÏÓÊÌÓ Á‡‰‡Ú¸ ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈÙÓÏÂ Ò ÔÓÏÓ˘¸˛ ÒÎÂ‰Û˛˘Ëı Û‡‚ÌÂÌËÈ:x1 (u, v) = φ( v) cos u, x 2 (u, v) = φ( v)sin u, x3 (u, v) = ψ ( v).ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÌÂÈ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÓÏds 2 = φ 2 du 2 + (φ 2 + ψ 2 )dv 2 .åÂÚË͇ ÔÒ‚‰ÓÒÙÂ˚èÒ‚‰ÓÒÙÂÓÈ Ì‡Á˚‚‡ÂÚÒfl ÔÓÎÓ‚Ë̇ ÔÓ‚ÂıÌÓÒÚË ‚‡˘ÂÌËfl, Ó·‡ÁÛÂÏÓÈ ‚‡˘ÂÌËÂÏ Ú‡ÍÚËÒ˚ ÓÚÌÓÒËÚÂθÌÓ Â ‡ÒËÏÔÚÓÚ˚. é̇ Á‡‰‡ÂÚÒfl ÒÎÂ‰Û˛˘ËÏËÛ‡‚ÌÂÌËflÏË ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏÂ:x1 (u, v) = sech u cos v, x 2 (u, v) = sech u sin v, x3 (u, v) = u − tgh u,„‰Â u ≥ 0 Ë 0 ≤ v < 2π.ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÌÂÈ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌÏ ˝ÎÂÏÂÌÚÓÏds 2 = tgh 2 udu 2 + sich 2 udv 2 .èÒ‚‰ÓÒÙ‡ ËÏÂÂÚ ÔÓÒÚÓflÌÌÛ˛ ÓÚˈ‡ÚÂθÌÛ˛ „‡ÛÒÒÓ‚Û ÍË‚ËÁÌÛ, ‡‚ÌÛ˛ –1, Ë‚ ˝ÚÓÏ ÒÏ˚ÒΠfl‚ÎflÂÚÒfl ‡Ì‡ÎÓ„ÓÏ ÒÙÂ˚ Ò ÔÓÒÚÓflÌÌÓÈ ÔÓÎÓÊËÚÂθÌÓÈ „‡ÛÒÒÓ‚ÓÈÍË‚ËÁÌÓÈ.åÂÚË͇ ÚÓ‡íÓ fl‚ÎflÂÚÒfl ÔÓ‚ÂıÌÓÒÚ¸˛, Ëϲ˘ÂÈ ÚËÔ 1.
ÄÁËÏÛڇθÌÓ ÒËÏÏÂÚ˘Ì˚È2ÓÚÌÓÒËÚÂθÌÓ ÓÒË x3 ÚÓ Á‡‰‡ÂÚÒfl ‰Â͇ÚÓ‚˚Ï Û‡‚ÌÂÌËÂÏ c − x12 + x 22 + x32 = a 2ËÎË ÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏÂ:x1 (u, v) = (c + a cos v) cos u, x 2 (u, v) = (c + a cos v)sin u, x3 (u, v) = a sin v,„‰Â c > a Ë u, v ∈ [0, 2π]. ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÚÓ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï˝ÎÂÏÂÌÚÓÏds 2 = (c + a cos v)2 du + a 2 dv 2 .åÂÚË͇ ‚ËÌÚÓ‚ÓÈ ÔÓ‚ÂıÌÓÒÚËÇËÌÚÓ‚ÓÈ ÔÓ‚ÂıÌÓÒÚ¸˛ (ËÎË ÔÓ‚ÂıÌÓÒÚ¸˛ ‚ËÌÚÓ‚Ó„Ó ‰‚ËÊÂÌËfl) ̇Á˚‚‡ÂÚÒflÔÓ‚ÂıÌÓÒÚ¸, ÓÔËÒ˚‚‡Âχfl ÔÎÓÒÍÓÈ ÍË‚ÓÈ γ, ÍÓÚÓ‡fl, ‚‡˘‡flÒ¸ Ò ÔÓÒÚÓflÌÌÓÈÒÍÓÓÒÚ¸˛ ÓÚÌÓÒËÚÂθÌÓ ÓÒË, Ó‰ÌÓ‚ÂÏÂÌÌÓ ‰‚ËÊÂÚÒfl ‚‰Óθ ÌÂÂ Ò ‡‚ÌÓÏÂÌÓÈÒÍÓÓÒÚ¸˛.
ÖÒÎË γ ̇ıÓ‰ËÚÒfl ‚ ÔÎÓÒÍÓÒÚË ÓÒË ‚‡˘ÂÌËfl x3 Ë ÓÔ‰ÂÎÂ̇ Û‡‚ÌÂÌËÂÏx3 = f(u), ÚÓ ÔÓÁˈËÓÌÌ˚È ‚ÂÍÚÓ ‚ËÌÚÓ‚ÓÈ ÔÓ‚ÂıÌÓÒÚË ·Û‰ÂÚ ‡‚ÂÌr = (u cos v, usonv, f (u) = hv), h = const,Ë ‚ÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÌÂÈ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 = (1 + f 2 )du 2 + 2 hf ′dudv + (u 2 + h 2 )dv 2 .ÖÒÎË f = const, ÚÓ ÔÓÎÛ˜‡ÂÏ „ÂÎËÍÓˉ; ÂÒÎË h = 0, ÚÓ ÔÓÎÛ˜‡ÂÏ ÔÓ‚ÂıÌÓÒÚ¸‚‡˘ÂÌËfl.É·‚‡ 8.
ê‡ÒÒÚÓflÌËfl ̇ ÔÓ‚ÂıÌÓÒÚflı Ë ÛÁ·ı 155åÂÚË͇ ÔÓ‚ÂıÌÓÒÚË ä‡Ú‡Î‡Ì‡èÓ‚ÂıÌÓÒÚ¸˛ ä‡Ú‡Î‡Ì‡ ̇Á˚‚‡ÂÚÒfl ÏËÌËχθ̇fl ÔÓ‚ÂıÌÓÒÚ¸, ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏ Á‡‰‡‚‡Âχfl ÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË:uvx1 (u, v) = u − sin u cosh v, x 2 (u, v) = 1 − cos u cosh v, x3 (u, v) = 4 sin sinh . 2 2ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ ÌÂÈ Á‡‰‡ÂÚÒfl ÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏvvds 2 = 2 cosh 2 (cosh v − cos u)du 2 + 2 cosh 2 (cosh v − cos u)dv 2 . 2 2åÂÚË͇ Ó·ÂÁ¸flÌ¸Â„Ó Ò‰·é·ÂÁ¸fl̸ËÏ Ò‰ÎÓÏ Ì‡Á˚‚‡ÂÚÒfl ÔÓ‚ÂıÌÓÒÚ¸, Á‡‰‡‚‡Âχfl ‰Â͇ÚÓ‚˚Ï Û‡‚ÌÂÌËÂÏ x3 = x1 ( x12 − 3 x 22 ) ËÎË ÒÎÂ‰Û˛˘ËÏË Û‡‚ÌÂÌËflÏË ‚ Ô‡‡ÏÂÚ˘ÂÒÍÓÈ ÙÓÏÂ:x1 (u, v) = u, x 2 (u, v) = v, x3 (u, v) = u 3 − 3uv 2 .èÓ Ú‡ÍÓÈ ÔÓ‚ÂıÌÓÒÚË Ó·ÂÁ¸fl̇ Ïӄ· ·˚ Ô‰‚Ë„‡Ú¸Òfl, ÓÔˇflÒ¸ Ó‰ÌÓ‚ÂÏÂÌÌÓ ÌÓ„‡ÏË Ë ı‚ÓÒÚÓÏ.
ÇÌÛÚÂÌÌflfl ÏÂÚË͇ ̇ Ú‡ÍÓÈ ÔÓ‚ÂıÌÓÒÚË Á‡‰‡ÂÚÒflÎËÌÂÈÌ˚Ï ˝ÎÂÏÂÌÚÓÏds 2 = (1 + ( su 2 − 3v 2 )2 du 2 − 2(18uv(u 2 − v 2 ))dudv + (1 + 36u 2 v 2 )dv 2 ).8.3. êÄëëíéüçü çÄ ì áãÄïìÁÎÓÏ Ì‡Á˚‚‡ÂÚÒfl Á‡ÏÍÌÛÚ‡fl Ò‡ÏÓÌÂÔÂÂÒÂ͇˛˘‡flÒfl ÍË‚‡fl, ‚ÎÓÊËχfl ‚ S3 . í˂ˇθÌ˚Ï ÛÁÎÓÏ (ËÎË ÌÂÁ‡ÛÁÎÂÌÌÓÒÚ¸˛) é ̇Á˚‚‡ÂÚÒfl Á‡ÏÍÌÛÚ˚È ÌÂÁ‡ÛÁÎÂÌÌ˚ÈÍÓÌÚÛ. é·Ó·˘ÂÌËÂÏ ÔÓÌflÚËfl ÛÁ· fl‚ÎflÂÚÒfl ÔÓÌflÚË Á‚Â̇. á‚ÂÌÓ Ô‰ÒÚ‡‚ÎflÂÚÒÓ·ÓÈ ÏÌÓÊÂÒÚ‚Ó ÌÂÔÂÂÒÂ͇˛˘ËıÒfl ÛÁÎÓ‚. ä‡Ê‰ÓÏÛ Á‚ÂÌÛ ÒÓÓÚ‚ÂÚÒÚ‚ÛÂÚ Â„ÓÔÓ‚ÂıÌÓÒÚ¸ áÂÈÙÂÚ‡, Ú.Â.