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1、tame核論文:整體函數(shù)域上tame核的計(jì)算【中文摘要】本文主要研究有限域上一元函數(shù)域(整體函數(shù)域)上順訓(xùn)(tame)映射的核,即tame核的結(jié)構(gòu)問(wèn)題。事實(shí)上,Quillen、Dennis和Stein、Kahn分別證明了離散賦值環(huán)、歐幾里德整環(huán)、整體域整環(huán)的K2群是其商域的tame核,故本文研究的也是整體函數(shù)域的K2群的結(jié)構(gòu)問(wèn)題。由Bass和Tate在1973年發(fā)表的結(jié)果可知,若能給出例外位范數(shù)的上界用以確定所有的例外位,再利用Steinberg符號(hào)工具,我們就有可能得到整體域的tame核的生成元集
2、?;谶@個(gè)思路以及Bass和Tate的結(jié)果,針對(duì)代數(shù)數(shù)域的情況,一些數(shù)學(xué)家用一些方法得到了例外位范數(shù)的明確的上界,從而得以成功計(jì)算出一些數(shù)域的tame核。2006年,Bass和Tate的結(jié)果被應(yīng)用到整體函數(shù)域的tame核生成元集的計(jì)算上。Weng成功估計(jì)出了適用于整體函數(shù)域的例外位的次數(shù)(與范數(shù)不同但存在直接關(guān)系)的上界:若令g為整體函數(shù)域F的虧格,假設(shè)F中至少有兩個(gè)有理位(次數(shù)為1的位),則例外位的次數(shù)的上界是6g-2。本文通過(guò)把陳勝和游宏在代數(shù)數(shù)域的K2計(jì)算中的方法運(yùn)用到整體函數(shù)域上,得到了更好
3、的例外位的次數(shù)的上界:假設(shè)整體函數(shù)域F中至少有兩個(gè)有理位,當(dāng)g=1時(shí),例外位的次數(shù)的上界是3;當(dāng)g>1時(shí),例外位的次數(shù)的上界是4g-2。最后我們計(jì)算了幾個(gè)橢圓函數(shù)域的tame核的生成元集,并以實(shí)例說(shuō)明了降低例外位的次數(shù)的界對(duì)簡(jiǎn)便計(jì)算帶來(lái)的好處?!居⑽恼縏hemainworkofthisdissertationisthestudyofthetamekernelforfunctionfieldswithonevariableonfinitefields(globalfunctionfields),n
4、amely,thestructureofthetamekernel.Infact,thisworkisboutthestructureoftheK2groupforglobalfunctionfields.SinceQuillen,Dennis&Stein,andKahnprovedrespectivelythattheK2groupofdiscretevaluationrings,Euclideanrings,andringofintegersofglobalfieldsarethetameker
5、neloftheirquotientfields.FromtheworkofBassandTatein1973,weknowthat:iftheupperboundofthenormoftheremainingplacesisobtained,thenafterinvestigatingtheseremainingplacesbyperformingsomenecessarycomputationswithSteinbergsymbols,wemaygetthegeneratorsofthetame
6、kernelofthefield.UsingBassandTate’sidea,manymathematiciansgainedsomesuchboundsandsuccessfullycomputedthetamekernelforafewalgebraicnumberfields.In2006,theresultofBassandTatewasusedinthefunctionfieldcase.WengprovedthatforaglobalfunctionfieldFwithgenusgan
7、datleasttworationalplaces,theupperboundofthedegree(differentfrombuthavingdirectrelationswiththenormofaplace)oftheremainingplacesis6g-2.EnlightenedbyBass,TateandWeng,weuseChenandYou’smethodforanumberfieldtothefunctionfieldcaseandimproveWeng’sbound.Wepro
8、vethatforaglobalfunctionfieldFwithatleasttworationalplacestheupperboundofthedegreeoftheremainingplacesis3wheng=1and4g-2wheng>1.Atlast,wegivetheexplicitgeneratorofthetamekernelforseveralellipticfunctionfields.【關(guān)鍵詞】tame核整體函數(shù)域K-理論【英文關(guān)鍵詞】ta