LONDONM ATHEMATICSAOLC IETMYO NOGRAPHS NEW SERIES SerEideist ors P.M .C ohnB .E .J ohnson LONODNM ATHEMATSIOCCAILE TMYO NGORAPHS NEWS ERIES Prevviooluuostfm hees MLoMnSo gwreaprpueishb hslbe yAd ac demic Pretwsohs oamle ln qiuesishr obuaeld dd resseidn .N tehVweo lumes Serwiibelpeslu is bhlbeydO x rfdoU nivertshirtyoo utuPthgwr ehoe rslsd . NEWS ERIES l.Di ophiannetiqituniRaee.l s B Cka.e r 2.T hSec hmuurl tiGprleigKoearrry p ilovsky 3.E xisltlceyln ogtsrieoaduG prsa hHaimg maanEndl izSacboettth Existentially Closed Groups GrahaHmi gman MatheImnast,ti ictault e UnivoefOrx srfidoty and ElizaSbceottht DeparotfMm aetnhte matics, ThAesu rtalNiaatniU onniavle rsity CLARENDON PRESS OXFORD · 1988 OxfoUrndi vePrrsesisWty,a ltSotrne eOtx,f oOrXd26 DP OxforNde wY orkT oronto DelhBio mbaCya lcuMttaad rasK arachi PetaJlianygSa ingapHoorneKg o ngT okyo NairoDbaire sS alaaCma pTeo wn MelbouArnuec kland anasds ociactoemdp ainni es BeirBuetr lIibna daNni cosia Oxfoisr dta r amdaer okfO xfoUrndi vePrrseistys Publisihnte hdUe n itSetda tes byO xfoUrndi vePrrseiNstyes w,Y ork ©GrahaHmi gmaannEd li zabSectoh1t 9t8,8 Alrli grhetss ervNeopd a,r otft hpisu blicmaatybi ero enp roduced, stoirnea rd e triseyvsatloe rtrm a,ns mititnae ndfy,o rmo rb ya nmye ans, electmreocnhiacn,pi hcoatlo,c orpeycionrgod,rio ntgh,e rwwiisteh,o ut thper ipoerrm issoifoO nx foUrndi vePrrseistys BritisLhi brCaaryt aloignPu uibnlgi cdaattiao n HigmaGnr,a ham Existenctilaolgslreyod u -(pLso.n don MathemaStoiccimaeoltyn ograNpehwss e.r ies; no3.) . 1.G roupTsh,e ooryf I.T itIIl.eS coEttl,i zabIIeIt.Sh e ries 512'.2Q2A 171 ISB0N- 19-853543-0 LibroafCry o ngrCeastsa liongP iunbgl icDaattiao n HigmaGn.(. G raham) Existenctilaolgslreyod u ps. (LondMoant hemaStioccaimleo tyn ogranpehwss e;r ., no3.) Bibliogpr.a phy: Incliunddeesx . 1.E xistenctilaolgslreyod u pIs.S. c oEttl,i zaLb.e th II.T itlIell..S eries QA171.H16928 75 12'.827 -7786 ISB0N- 19-853543-0 Typeasnepdtr initnNe odr thIreernl abnyTd h Uen iverPsrieBtseisle fsas t Preface Thbiso ogkr ewo faoc uotu orfls eec tguirvbeeyGsn r ahHaimg man durtihnaegc adyeem1ai8r9c3 1 9-8t4h,e yleoaafsr t th einsou fr et he WaynfPlreeostfseo orfsP huirMpea themaattt hiUecn sis vieotrfy Oxf.oT rhdceo uwrasgsei vaesn i annt roductiocnl otsoe de xistentially grouapnwsda, is n tetnobd eoe fid n tteora enmsyat t hteimcwaiiaatnnh intiergnre ostuthp e oorlr oygw ihcia,ll bese oi negs saticobc lfier st-year gradsutautd.Tee h nbeto sorke fltehcaiti.ssm Thteh yeo ofer xisatlcellnyot gsireodiu ospfi s n tieinrte ssr tio gwhnt ; anidht a asni nterheissottfcio hnragyn rgeilnagt wiiotnhsw hitidhpeesr mathteimdcaiasllci ionpfweh si icftho ramp sa. rI tni tbse ginintnih neg , hanodBfs .H . N eumaannWdn. RS.c oitftrto m,ep dao rtfth teh yeo ofr infignriot.Aue pn sgMuasc inatmyoorntegrh, sm e,a dieatp raotfm odel thye;oa rnd M. iZnai f neudgalmeerwn,ot rtakrl,ao mnresdifit nto recutrhsyeiB.oou rnst o me ofr etchweeon ritmvks oe rmreuy c ihtn h e spiorftih etea ryleyao rfs s tuehbce.jTt encihquelso agfriruecos ames d necaerbsysu,t p rtaihrmeay i mt ofii nsod u tths eo rotfts h itnhtgca sa n goo ni tnh ien fignripotsuTe.h iitssr ufeoi,rn stoaftn hcieem ,p ortant worokfK .H iciktnih nfii esla dna;dl ostfoh e owfRo. r PkEh .i lalnidp s, otsh,ei rnt hcel orseellayat naedcd t fiievl(edn torte ahteerodef ) relaetxiivsetlceyln otgsirepaodsluI .lit ys alsspoio rftit hthen eso et es, whoasieimn s o tp rteoass eynstt aecmocautnaitfi c n oifss hueebc;djbt ut toa ssgirsottu hpie so(trrsae rscseht udoerne tsst abmlaitshheed matictiofia ntndhs ew)ia iryn atc oo ronfte hres iuerbcw jth ihcahis t s owcnh aracfltaevroaiunysrdet;w ti h ci crhe ciosg gnrizoatubhplye y.o r Wed on ottrt yoi ncelvuedrey tthihaksitn n ogaw bno ut existentially clogsreodwu epm se;rh eolptyeo tghireve eas dueffirc uinednetr standing ofa,ni dn tienrt,ehs seute bt ctj oi nshpiitmror e e faudr thheirm sfeolrf . Al iosoftr igsionuaarnlcfd eu sr rtehaeidrgsi i nvigetn nh b ei brlaip.oh gy We ndooat s suanmpyer ikonro wloefld oggaein cdt harele lc ursive functthiyeto ohnrwa itbl enl e eidisen dc liutndh teeed. x t A larogfte h biposa-oi rbksta soentd hw eo rokfM .Z ie,gt loegrether with bywKo .Hr ikc akniAdn.M aci.nB tubytyrn eom eaanlslt hoefi r mateircsio avleh re.erL dea rpgraeto sfZ ie'g(sl91 e8rp0a)p reerm ain beyonsdc otophftee h bios.o F koerx amhpelg ei,va e dse tailed classiofifc (at0th0,ie) o -ngi ecgn rpeo.sruH ic'k(si9 1n8)5p apdeird vi Praecfe noatp puenaatrfi ttlhe biro soh kab de werni nta,tn cedo nsenqouneen tly oft hree souftl htpasat p aeriren clhued.rMe eadn oyt htehrih nagvse beeonm itbtceeadua s ger oupe-ttivhcieaeolwr phoalisen udts to conceonnatd riafftetery eopnfaet p pr.o ach Somoeft hied eians b tohoaikr,sa e sf aarsw ea raew a,r enbeuwt; mosotft hecmab nef ou,in nsdo mfeo romra nhoe,tir nea rwloir.ek rs Gene,rw aedl oln yogti avcek nowliendt ghmee fntotserspx etc ific theo,mr aenmoysfw hiacrhse t aitnde idff etreernmti, nc ooln,ot geyxt angde nefrraotlmhio etr yil vg eiirnos.an s Existcelnotgsireaodlwu lepyrs e difisrcsbutysS sceo(dt15 t91a )n d B.H .N eum(an15n92& 1793.M) osotft hbea sriecsi untl htfiesr st chahpetarererde u teot h.e m Thsee ccohnadpi tbssea erd t hoen owfHo irckak niMdna cintyre (918,0a )lthsooumogetfh h p er oaorfdesi ffnetr.e Chap4ct oenrt maoisbntsasli ryce siurnle tcsu trhsei,woo hrniyc cahn bef ouinandt extsbuoacosRhk o g(e91r6s.7 ) Three osftt h beo oibksa sberdo aodntl hwyeo rokfZ ie(g9l18e,0r ) althnoouatglt hlhr ee saurlheti, (ss f eoxrpa lm,Te heor5e.3am 1nsd 5.5a 1rdeu teoH icakniMdna cin(9t108y)r)Me.a noyft hteh reeoms cabnef ouinZndi leegpra'psie anrl sm eoxsattc htsela ymf eo, rb mut in somcea swees htaavkteeh nie d ebautstr etatheeddmir ffeen.It nl y parutl,iZa ciredgolneeosrt dgiasmicegnuse s nsea rlalhl ig;osa f ma erse playedt hfiuenn idcteoerd er ueolsAf.s a r eshuedl oten so t have Rg-eingcer ro.uH poswreiv,ste h obuenl odt tehdoa ut(r 0 0,)- generic existcelnotgsireaodlau lrpwyesh atl e,Za rineodgt h,ce arglseln eric grposuS.o moef t hree s,uf lotrs exTahmeRp ellea tive-Subgroup Theorem c(asloTlmheeGedte inmeersa lE mHbiegdTmdheaioennrm g,) werep raolbvsyeoC d . MFil.le bru,Mt i lhlaensre vpeurb ltihsihse d wo.r k Thecsoem meanritens t eonndalesyad b rooaudt ,lt iogn ietvhee reasdoemired o ewfah etrole o fooktr ho er igriens.Tau hllhet i ssyo tfo r manoytf h erseesi uisln tvdsoF .lo verex palm,te hteh eotrhaeafi mtn itely genegrraotiueespdm bedidenav beelrxeyi stcelnotgsireaoidluaf lpn y d onilifyht a sso lvwaobrpldre o bwlateshm ce o mbrienseudwl otrb kyo f Neum(a17n93n,S) imm(o17n93,sa) nMda ci(nt17by29)ra;ens do moef thied eianCs h ap9to erri gwiinMtaahtc eidn( t17y92.raW e)ec aonn ly apologize inu naddevrtathnadecki eiffi nctfguao lsrtka lnwooafty s givcirinetged v,we hne iriteus n doudbut.ea bly Sevpeeroahplal vbeee ehne ldpufrutilhn wegr iotfti hnbigoos k b,u t we wopualrdt ilciutkloeta hralPnyek t er n,nNw ehuomtsaiem ely inetcetrdijuorntishnl ege cteunrseutsrhp eardto woefrcseo rdrae,nc dt e madmeo rceo mhpernes.H ieba llegsaovv ea luaadbvldieuc reti hneg wriotfti hnbigos o Wkew. o ualldls iotk ote h aLnakKc oiv ,af cotsrh e manhyep lfudli scutshshaietao nntdsh s ee caountdhh aowdrh itlhee findarlao fftt hb iosow kab se ipnrge piaCnra endb. e rra Praecfe vii Thbiosow ka s bieOngx ufnuo nrddfe nurd ifnrgoa mnS ERrCe asrech gr,aa nntidwt a cso pmlewtheitdlh seee cond aafu letlhoowarst h hiepl d thAeu strNaaltiiUaonnni avlei rCnsa inrtbaWye.e rw oullidtk ote h ank bootfth h eisnes tiftoturht seiuioprntp s.o r G.H. Illinois E.S . Canberra Octob1e9r8 6 Thearrteew p oat ricduelbtathrIsam tu satc knohwel.reO ednigetse o WilHfordie,dgsw hroe -awmayki ennteeidrnt e hssiutseb c,jwt hehne lecttuotr heAedb erdmeeeento iftn hgBei r tMiasthh emCaotlilcoal qui,iu nmA pr1i89l.3H aIdn ofto utnhdta atsl tki mgu,Ilw aotuilnd certnaohitan vlleey c tountr hepidas r tic.uT lhsaeer c otno,dop f i dcebt cou,ir tssom e yc o-hao,uDr trE . SAc..oA tsot irgidnealleildtvy,he er lectwuerrveeers ro yu hgeh.w nleI fcth uoonufnkt es c aercsyos nnecting matetrhileae lvo;ef pl r evkinoouwsl wehdigIcae hs suomfme yd audience avnaudrn issetyde mwaiatdniIedcm l aaylda len y u;m boefr underlaimtbiekes et.Tsa htea osfkr edutchiminesgs t sos omething publiwsahisam bmnlesaeen udn envbiuaDtbrS l ceot;ta tc kiwtli etdh enearngpdyta ie,an ncIdea mi mmneseglrya tteohf eu(rlI.I df i ndo t fetehlwa htas thh eap sr odduecseewdre voletflsh m ea themat,i cal public Iw ounlodct o nttihfinecu teoi fpo unt mtyin nagm, e whie,tro hsnt he tiptalogefwe h airtse ahlewlroy .r )k G.H.