ΛϑΟϧτϨʔγϣϯ ͱ͍͏. F (M, dM ) a b Fa ⇢ Fb ྫ1 ༗ݶݸͷू߹ɹɹɹɹɹɹɹɹɹɹɹ ͔Β࡞ΒΕΔٿϞσϧ ɹɹɹɹɹɹ filtration ɹɹɹɹɹɹ Λ࡞Δ. (લͷεϥΠυͷྫ) ͨͩ͠, ɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹ. ͜͜Ͱ, ٿϞσϧϑΟϧτϨʔγϣϯͱ͍͏. ※ Cech complex alpha complex ͱhomotopy ಉ. B ( x ; a ) := { y 2 M | dM ( x, y ) a } B(X) = {Xa } Xa := S i B ( xi; a ) X = { x1, . . . , xn } ⇢ M F = {Fa | a = 1, . . . , N}
ɹɹɹɹɹɹɹϗϞϩδʔͷੜݩͷϩόετੑΛද͢. 2 : ଟ͘ͷ߹, ର֯ઢʹ͍ۙϊΠζͱݟͳ͢(ੜଘ͕͍࣌ؒ). 3 : ൃੜͯ͠ফ໓͢ΔੜݩҰͭͱݶΒͳ͍ͨΊ, ύʔγεςϯτਤ ͷଟॏू߹Ͱ͋Δ. pers( x ) = d b x = ( b, d ) 2 D (F) R2
౷ܭత ͳ͜ͱΛߟ͑Δࡍʹ͋Δఔͷߏ͕ཉ͍͠. D = {D1, . . . , Dn } ϕΫτϧۭؒɹ ͱϕΫτϧԽͷࣸ૾ɹɹɹɹɹΛ༻ҙ͢Δ. ͦ͏͢Δͱ, ฏۉͳͲΛͦͷϕΫτϧۭؒͰߟ͑Δ͜ͱ͕Ͱ͖Δ: H : D!H 1 n P (Di) 2 H ฏۉ? 1 n P Di ߟ͑Δ͖͜ͱ 1 : ͦͷϕΫτϧԽͷۭؒͱࣸ૾ֶతʹѻ͍͍͢ͷ 2 : σʔλղੳͷࡍʹྑ͍ੑ࣭Λࣔ͢ͷ 3 : ܭࢉίετ͕ΑΓগͳ͍ͷ
౷ܭత ͳ͜ͱΛߟ͑Δࡍʹ͋Δఔͷߏ͕ཉ͍͠. D = {D1, . . . , Dn } ϕΫτϧۭؒɹ ͱϕΫτϧԽͷࣸ૾ɹɹɹɹɹΛ༻ҙ͢Δ. ͦ͏͢Δͱ, ฏۉͳͲΛͦͷϕΫτϧۭؒͰߟ͑Δ͜ͱ͕Ͱ͖Δ: H : D!H 1 n P (Di) 2 H ฏۉ? 1 n P Di ߟ͑Δ͖͜ͱ 1 : ͦͷϕΫτϧԽͷۭؒͱࣸ૾ֶతʹѻ͍͍͢ͷ 2 : σʔλղੳͷࡍʹྑ͍ੑ࣭Λࣔ͢ͷ 3 : ܭࢉίετ͕ΑΓগͳ͍ͷ ͍͍ؔ(ਖ਼ఆΧʔωϧ) ɹɹɹɹ Λ༻ҙ͢Δͱ͜Ͱղܾ͢Δ. K : D ⇥ D!R
kL( x, y ) = h x, y i kP ( x, y ) = (h x, y i + c )d kG( x, y ) = e k x y k2 2 2 ఆٛ ू߹ɹ ্ͷਖ਼ఆΧʔωϧ ɹ ɹɹɹɹɹ ͱ࣍Λຬͨؔ͢Ͱ͋Δ. • ରশͰ͋Δ: • ҙͷɹɹɹɹɹɹ ʹରͯ͠, ߦྻɹɹɹɹɹ ͕ਖ਼ఆͰ͋Δ. (͜ͷߦྻΛάϥϜߦྻͱ͍͏) k : ⌦ ⇥ ⌦!R ⌦ k ( x, y ) = k ( y, x ) x1, . . . , xn 2 ⌦ ( k ( xi, xj))i,j=1,··· ,n Kernel method Χʔωϧ๏ʹ͍ͭͯ[ਫ, 14]Λࢀর
ҙͷ ɹʹରͯ͠, ɹɹɹɹ ɹ ɹ ͷݩͰ͋Δ. • ϕΫτϧͷுΔۭؒ ɹɹͰີͰ͋Δ. • ҙͷɹ ɹ ͱɹɹɹ ʹରͯ͠, ɹɹɹɹɹ ཱ͕͢Δ(࠶ੜੑ). k Hk x 2 ⌦ k (· , x ) : ⌦!R Hk Hk x 2 ⌦ f 2 Hk h f, k (· , x )iHk = f ( x ) Span{ k (· , x ) | x 2 ⌦} Kernel method
ҙͷ ɹʹରͯ͠, ɹɹɹɹ ɹ ɹ ͷݩͰ͋Δ. • ϕΫτϧͷுΔۭؒ ɹɹͰີͰ͋Δ. • ҙͷɹ ɹ ͱɹɹɹ ʹରͯ͠, ɹɹɹɹɹ ཱ͕͢Δ(࠶ੜੑ). k Hk x 2 ⌦ k (· , x ) : ⌦!R Hk Hk x 2 ⌦ f 2 Hk h f, k (· , x )iHk = f ( x ) Span{ k (· , x ) | x 2 ⌦} Kernel method ࠶ੜੑ͔Βੵ࣍ͷΑ͏ʹܭࢉ͞ΕΔ: ɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹɹ h k (· , y ) , k (· , x )iHk = k ( x, y ) σʔλɹɹɹͷϕΫτϧදݱɹɹɹɹɹɹͰ͋Δ(RKHS ϕΫτϧ). x 2 ⌦ k (· , x ) 2 Hk
Ek( µ ) := Z k (· , x ) dµ ( x ) 2 Hk Mb(⌦) 3 Mb(⌦) ⌦ σʔλۭؒɹ ্ͷଌ()ϕΫτϧԽ͢Δ͜ͱ͕Ͱ͖Δ. ⌦ Kernel method ※1 : ੵBochnerੵ(BanachۭؒʹΛ࣋ͭؔͷੵ) ※2 : ܦݧʹΑΔຒΊࠐΈΧʔωϧฏۉͱ͍͏: ※3 : ैདྷ, ೋͭͷ͕֬ಉ͔͡Ͳ͏͔ΛRKHSͰߟ͑ΔͨΊʹ ߟҊ͞Εͨ: µX = 1 n P xi ) Ek ( µX ) = 1 n P k (· , xi ) P = Q , Ek(P) = Ek(Q)
Ek(⌫)kHk (µ, ⌫ 2 Mb(⌦)) ໋ [Sriperumbudur et al., 11] ਖ਼ఆΧʔωϧɹɹɹɹɹɹɹ ͕ C0-universalΛຬͨ͢ͱ͢Δ. ͜ͷͱ͖, ΧʔωϧຒΊࠐΈɹ ୯ࣹʹͳΓ, ͕ͨͬͯ͠ɹ ڑΛఆΊΔ. k : ⌦ ⇥ ⌦!R Ek dk ※1 : C0-universalͱରԠ͢ΔRKHS͕ແݶԕͰফ͑Δ࿈ଓؔͷͳ͢ ۭؒʹີʹೖ͍ͬͯΔ͜ͱ: ※2 : ઢܗΧʔωϧɹɹɹɹɹɹɹ C0-universalͰͳ͘, ɹɹΨεΧʔωϧɹɹɹɹɹɹɹɹC0-universalͰ͋Δ. Hk ⇢ C0(⌦) kL( x, y ) = h x, y i kG( x, y ) = e k x y k2 2 2 HkL ⇠ = Rd, dim HkG = 1 (⌦ = Rd)
Fourier features [Rahimi and Recht, 07]ʹΑΔߴۙࣅΞϧΰϦζϜʹΑΓ ܭࢉ࣌ؒɹ ʹؔ͠ઢܗʹམͪΔ. k Ek ( µw D ) Ek ( µw E )k2 Hk = X x 2 D X x 02 D w ( x ) w ( x 0) k ( x, x 0) + X y 2 E X y 02 E w ( y ) w ( y 0) k ( y, y 0) 2 X x 2 D X y 2 E w ( x ) w ( y ) k ( x, y ) RKHSϕΫτϧɹɹɹ ΛܭࢉػͰදࣔ͢Δ͜ͱࠔ͕ͩ, ੵܭ ࢉͰ͖Δ(ΧʔωϧτϦοΫ): ڑੵ͔Βܭࢉ͞ΕΔ: Ek(µw D ) Kernel on persistence diagram
ͳΒ, ཱ͕࣍͢Δ: ͨͩ͠,ɹɹ ɹ ʹґଘ͢ΔఆͰ͋Γ, M ⇢ Rd p > d + 1 X, Y ॏΈؔͱΧʔωϧΛదʹબ͢Δͱ, σʔλͷઁಈʹ҆ఆͳRKHS ϕΫτϧΛಘΔ(㱻 ౷ܭղੳ݁ՌϊΠζʹେ͖͘Өڹ͞Εͳ͍). EkG (µwarc Dq (X) ) EkG (µwarc Dq (Y ) ) HkG L(M, d; C, p, )dH(X, Y ) L ( M, d ; C, p, ) = p 2 p p ddiam( M ) + 4 p ( p 1) p 1 d ! CM diam( M ) p 1 dC dH ( X, Y ) = max ⇢ max x 2X min y 2Y dM (x , y) , max y 2Y min x 2X dM (x , y) CM M Kernel on persistence diagram
ؔͰ͋Δ. ※2 : ܭࢉྔੵܭࢉ͕͋ΔPWGKΑΓଟ͍. Persistence scale-space kernel (PSSK) [Reininghaus et al., 15] ※1 : Persistence scale-space kernelPWGKͷҰྫͱݟͳͤΔ: ※2 : ॏΈؔݻఆ͞Ε͍ͯΔ. ※3 : Bottleneck distance stability Λຬͨ͞ͳ͍. Comparison with other vectorizations wpss( x ) = ( 1 x 2 D 1 x 2 D ⇤ D⇤ = {(d, b) | (b, d) 2 D} KPSS(· , D ) := X x 2 D [ D ⇤ wpss( x ) kG (· , x ) = D D 7! D( k, t ) = k -th largest value of max { min {t bi, di t}, 0 } D 7! D( y ) = P x 2 D e k x y k2 4 t e k x ¯ y k2 4 t (¯ y = ( y2, y1 ) for y = ( y1, y2 )) L2(N ⇥ R) D
ɹΛฏۉʹͭ֬. ※1 : Persistence imageຊݚڀख๏ͷࢄԽͱࢥ͑Δ: ɹɹɹɹɹ ͱ͢Δͱ, ɹɹɹ ɹɹɹ ΛάϦου ɹɹɹɹɹɹɹɹ ্Ͱੵͨ͠ͷ ※2 : ߦྻͳͷͰ, ༗ݶ࣍ݩ ϕΫτϧͱݟͳ͢ͱ ܭࢉ͕ૣ͍. ※3 : ϝογϡαΠζదʹ બͿඞཁ͕͋Δ. Comparison with other vectorizations z( x ) = k ( x, z ) (ai 1, ai] ⇥ (aj 1, aj] Ek(µw D ) PI(D)i,j D 7! PI( D ) i,j = P x 2 D w ( x ) R Pi,j x ( z ) dz Pi,j := (ai 1, ai] ⇥ (aj 1, aj] z z M = 8 M = 20 M = 100
random packingΛ ׂ͢ΔॆరʹରԠ͍ͯ͠Δ. σʔλ[Saadatfar et al., 17]ΑΓ. • λϯύΫ࣭ͷߏ (from PDB) — SVMʹΑΔྨ Binding and non-binging drug 100.0% The taut and relaxed forms of hemoglobin 88.9% ([Xia et al., 14] ΑΓߴ͍ྨੑೳΛ͍ࣔͯ͠Δ)
ɹɹɹؔͰ͋Δ. INRIAͷFrédéric ChazalΒͷάϧʔϓ͔Βpersistence landscapeͷத৺ۃ ݶఆཧ, Bootstrap๏, ৴པ۠ؒ, subsampling๏, ऩଋϨʔτʹؔ͢Δݚڀ͕ ఏҊ͞Ε͍ͯΔ(BanachۭؒʹΛ࣋ͭ֬มͷཧͷԠ༻). PWGKBanachۭؒʹΛ࣋ͭ֬มͱݟͳͤΔ + Χʔωϧ๏ͰΒ Ε͍ͯΔཧΛద༻Ͱ͖Δ. D 7! D( k, t ) = k -th largest value of max { min {t bi, di t}, 0 } L2(N ⇥ R)
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| x 2 D` } ( D`) = median{k xi xj k | xi, xj 2 D`, i < j } C = median{C` | ` = 1, · · · , n} = median{ (D`) | ` = 1, · · · , n} kG( x, y ) = e k x y k2 2 2 , warc( x ) = arctan( C pers( x )p) ॏΈؔͷϕΩɹʹؔͯ҆͠ఆੑఆཧͷԾఆɹɹɹɹ ͱ༻͍Δσʔλ ɹ ͔Βऔ͍ͬͯΔͨΊ, ɹɹͱݻఆ͢Δ. ɹΛม͑ͯPWGKͷྨ ਫ਼͕େ͖͘มԽ͠ͳ͍͜ͱSVMͷ࣮ݧͰ֬ೝࡁΈ. p > d + 1 R3 p = 5 p p Parameters
มͰ͋Δ. e k x y k2 2 2 = Z R2 e p 1 z ( x y ) 2 2⇡ e 2 2 k z k2 dz ⇡ 1 M M X a =1 e p 1 za ( x y ) = 1 M M X a =1 e p 1 zaxe p 1 zay z1, . . . , zM ⇠ N(0, 2I2) X x 2 D X y 2 E w ( x ) w ( y ) e k x y k2 2 2 ⇡ 1 M M X a =1 X x 2 D w ( x ) e p 1 zax ! 0 @ X y 2 E w ( y ) e p 1 zay 1 A ⇤ ※ : ෳૉڞ RKHSϕΫτϧͷੵ࣍ͷΑ͏ʹۙࣅ͞ΕΔ: