Another proof of M. Kontsevich formality theorem
Another proof of M. Kontsevich formality theorem
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M. Kontsevich 形式定理的另一个证明
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发表时间:
1998
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通讯作者:
D. Tamarkin
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作者:
D. Tamarkin
Thisisadraftofpaperin which weannounceaplan ofan alternativeproofofM . Kontsevich form ality theorem [7]. The basic idea is to equip Hochschild cochains ofan associativealgebra A with a structureofhom otopy Gerstenhaberalgebra and to prove the form ality ofthisGerstenhaberalgebra. See [2]. The authorwastold aboutthisidea by BorisTsygan abouta yearago. The hom ologicalobstructionsto form ality vanish in thecaseA = SR ;C 1 (R ). In otherwords,theGerstenhaberalgebrasform ed byHochschild cohom ologyarenot deform able.The operad e2 governing GerstenhaberalgebrasisKoszul,therefore it has a canonicalresolution which we denote by H E2. The Hochschild cochains of an associativealgebra havea canonicalstructureofan algebra overtheoperad B1 (see [3]and section 2.1.5),and itsu ces to constructa m ap H E 2 ! B1 . Such a m ap m ustinduce the correctstructure ofGerstenhaberalgebra on the Hochschild cohom ology and the correctGerstenhaber bracket on Hochschild cochains. These conditionsareform alized in Theorem 2.1,and in thesections2.2.3 and 3 M .Kontsevich’stheorem isdeduced from Theorem 2.1. In thesection 4 weform ulateTheorem 4.2 and show thatitim pliesTheorem 2.1. Therestofthepaperisdevoted to theproofofthistheorem . In section 5 we construct a m ap k :B1 ! e2. The existence ofsuch a m ap (satisfying thecondition 1 ofTheorem 4.2)isa directcorollary ofEtingof-Kazhdan theorem on quantization ofbialgebras. In section 6 we construct the operad F . Ifwe new that the hom ology operad ofB1 ise2 we could take F = B1 . Letusoutline the m ain stepsofconstruction ofF . Suppose we have an operad X in the category ofdg-coalgebraswith counit (forexam pletheasym m etricoperad Asfrom section 6.1.6)and a dgcoalgebra with counitW . Then we can de ne a notion ofan X -algebra on W . Itisthe sam e as in the case ofusualoperads,butin addition we require thatallstructure m apsbe coalgebra m orphism s. Then we consider the case when W is cofree as a graded coalgebra,thatisW = TV ,and we prove thatin this case X -algebrason W are determ ined by a collection ofoperationsTV ! V and thatthe relationsbetween these operationsare described by a certain dg-operad,which we denote by O (X ).