On the equivalence classes of spherical curves by ...Joint work with Noboru Ito University of Tokyo...
Transcript of On the equivalence classes of spherical curves by ...Joint work with Noboru Ito University of Tokyo...
JointworkwithNoboruItoUniversityofTokyo
Ontheequivalenceclassesofsphericalcurvesby
ReidemeistermovesⅠandⅢ
MegumiHashizumeMeijiUniv.Organiza?onforthe
StrategicCoordina?onofResearchandIntellectualProper?es/OCAMI
25,12,2017
Reidemeistermovesofsphericalcurves
SphericalcurveReidemeistermovesofsphericalcurves
Inthistalk,wefocusonRIandRIII.
RIRIII
RII
Mo9va9onAnexampleofHagge-Yazinski
T.HaggeandJ.Yazinski,OnthenecessityofReidemeistermove2forsimplifyingimmersedplanarcurves,BanachCenterPubl.103(2014),101–110.
Mo9va9onAnexampleofIto-Takimura
N.ItoandY.Takimura,Onanontrivialknotprojec?onunder(1,3)homotopy,TopologyAppl.210(2016),22-28.
Moreover,theyfoundaninfinitenumberofexamples!
Ques9on
WhatsphericalcurveisobtainedfromthesimpleclosedcurvebyRI,RIIIandambientisotopy?
?RI,RIII
Today’sproblem
P:asphericalcurveWhatsphericalcurveP’isobtainedfromPbysomeRI’s,asingleRIIIandambientisotopy?
someRI’s,singleRIIIPP’
PreliminariesDef(keyopera?ons)
※講演ではβのみ上記のように両方の操作を紹介しました.しかし,講演中に谷山公規氏(早稲田大)に頂いたコメントの通り,局所的な部分の取り替え操作なのでα,βいずれも右側のみ(もしくは左側のみ)の操作だけで十分でした.本スライド報告は操作後に得られる球面曲線が大きく異なるので両方向の操作を紹介しておきます.
Preliminaries
singleRIIIRI
RI×3 singleRIIIRI×3
singleRIII
Def(reducible)P:asphericalcurveonS2
D1,D2:disksonS2
If∃E(⊂S2):circles.t.D1⊔ED2=S2
E∩P={adoublept.d}T1⊂D1,T2⊂D2,thenwesaythatPisreducible.If∃E,thenwesaythatPisirreducible.
Preliminaries
E
D1D2
MainresultP:asphericalcurven(P):thenum.ofthedoublepointsofP
P,P’:sphericalcurvesSupposeP,P’:irreducible
PP’Then,|n(P’)-n(P)|=0,1or3.Inpar?cular,
・|n(P’)-n(P)|=0⇔PP’・|n(P’)-n(P)|=1⇔PP’・|n(P’)-n(P)|=3⇔PP’
singleRIII
singleβsingleα
someRI,singleRIII
RIII
AsphericalcurvePvertexvPP,P’:sphericalcurves
IfP’isobtainedfromPbysomeRI’s,asingleRIIIandambi.iso.,thenthereexistsanedgefromvPtovP’.
ComplexinducedbysphericalcurvesandRIII,α,β
someRI,singleRIII
RI,RIII
PP’RI,RIII
ComplexinducedbysphericalcurvesandRIII,α,β
P,P’:irredu.sphericalcurvesd3(P,P’):=min{k|P’isobtainedfromPbysomeRI’s,kRIII’sandamb.iso.}
CorollaryofmainresultP,P’:sphericalcurves
RI,RIII RIII,α,βPP’ ⇔ PP’
講演では上記を主結果の系として紹介しました.しかし講演後,早野健太氏(慶應大)から指摘・質問を頂き,当Cor.が主結果から直ちに得られるという報告は適切ではないとわかりました.従いまして,本講演記録では当Cor.の報告を控えさせていただきます.
KeyLemma
P:asphericalcurve
fc(P):thenum.ofprimefactorsofP
KeyLemmaRI
RIII
type1-
type1+
RIIIRIII
type1-
type1+
RIII
type2-
type2+RIII
講演では局所変形を施す部分の外側の繋がり方の場合分けが不十分でした.講演中に瀧村祐介氏(学習院中)に頂いたコメントにより補完しました.
KeyLemmaP:asphericalcurven(P):thenum.ofthedoublepointsofPSupposethatP’isobtainedfromPbyRI’s,asingleRIIIandambientiso.Thenwehave;fc(P’)=fc(P)+n(P’)-n(P)+1#{RIII|type1+}+2#{RIII|type2+}+(-1)#{RIII|type1-}+(-2)#{RIII|type2-}