群论导论（第4版）（英文版）

《群论导论(第4版)(英文版)》介绍了：GroupTheoryisavastsubjectand,inthisIntroduction（aswellasintheearliereditions）,Ihavetriedtoselectimportantandrepresentativetheoremsandtoorganizetheminacoherentway.Proofsmustbeclear,andexamplesshouldillustratetheoremsandalsoexplainthepresenceofrestrictivehypo-theses.！alsobelievethatsomehistoryshouldbegivensothatonecanunderstandtheoriginofproblemsandthecontextinwhichthesubjectdeveloped.Justaseachoftheearliereditionsdiffersfromthepreviousoneinasignifi-cantway,thepresent（fourth）editionisgenuinelydifferentfromthethird.Indeed,thisisalreadyapparentintheTableofContents.Thebooknowbeginswiththeuniquefactorizationofpermutationsintodisjointcyclesandtheparityofpermutations;onlythenistheideaofgroupintroduced.ThisisconsistentwiththehistoryofGroupTheory,forthesefirstresultsonpermu-tationscanbefoundinan1815paperbyCauchy,whereasgroupsofpermu-tationswerenotintroduceduntil1831（byGalois）Butevenifhistory