reciprocal魔兽世界服务器维护
魔兽世界服务器维护 时间:2021-01-13 阅读:(
)
CURRICULUMINSPIRATIONS:www.
maa.
org/ciInnovativeOnlineCourses:www.
gdaymath.
comTantonTidbits:www.
jamestanton.
comWOW!
COOLMATH!
CURIOUSMATHEMATICSFORFUNANDJOYAPRIL2016PROMOTIONALCORNER:Haveyouanevent,aworkshop,awebsite,somematerialsyouwouldliketosharewiththeworldLetmeknow!
Iftheworkisaboutdeep,joyous,andrealmathematicaldoingI'llhappilymentionithere.
***Peopledomathvideos!
CheckoutMarcChamberlain'shttps://www.
youtube.
com/watchv=bCiQOwP4LrY.
WhydoesworkTHISMONTH'SPUZZLER:Itispossibletocolorthefirsteightcountingnumberseacheitherredorbluesothatweneverhavethreedistinctintegers,,andallthesamecolor.
CanthesametaskbecompletedwiththefirstninecountingnumbersWhatisthesmallestsothateverycoloringofthenumbers1,2,3,…,eitherredorblueissuretohaveamonochromatictripleHowdoestheanswerchangeifwepermitgeneric"triples"with(Nowweneedeachandtobedistinctcolorstoo.
)JamesTanton2016www.
jamestanton.
comandwww.
gdaymath.
comRAMSEYTHEORYHereisaclassicresult:Ifsixuniversitystudentsareselectedatrandom,thenthereissuretobeeitherthreestudentsamongthesixwhoaremutualfriendsorthreestudentswhoaremutualstrangers(orboth).
(Weareassumingherethatfriendshipisreciprocal:IfAlbertisfriendswithBilbert,thenBilbertisalsofriendswithAlbert.
Beingastrangerisreciprocaltoo.
)Here'sthereasoning:Chooseoneofthesixstudents,Cuthbert.
Therearefiveotherstudentseachofwhichheiseitherfriendswithorastrangerto.
SupposeCuthbertisfriendswithamajorityofthesefive,thatis,friendswithatleastthreeofthem.
(If,instead,heisastrangertoamajority,thenswitchthewordsfriendandstrangerinwhatfollows.
)Amongthesethreepeople,ifanytwoaremutualfriends,thenwehaveatripleoffriends:Cuthbertandthosetwo.
Ifnoneofthosethreearefriends,thenwehavefoundatripleofstrangers.
Theresultisnottrueforjustfivepeopleselectedatrandomasseenbythisgraphic.
Hereeachdotrepresentsastudentandarededgeindicatesmutualfriendsandablueedgemutualstrangers.
Nothreepeopleareconnectedbyedgesallofthesameonecolor.
Intermsofcoloreddiagrams,ourpartyresulttranslatesasfollows:Drawsixdotsonapageandthe15edgesbetweenallpossiblepairsofdots.
Itisimpossibletocolorthoseedgesredandblueandavoidamonochromatictriangle.
Togeneralizethisidealetdenotetheleastnumberofdotsoneneedstodrawonapagesothatifweconnectallpairsofdotswitheitherredorblueedges,thereissuretobeeitherasetofdotswithalltheedgesamongthemredorasetofdotswithalltheedgesamongthosedotsblue.
(Thisisassumingthatsuchaleastnumberexists!
Maybenomatterhowmanydotsonedrawsonecanalwaysavoidred"cliques"ofsizeandbluecliquesofsize)Theideaofstudyingthenecessarysizeofasystemtoensurecertainsub-substructuresexistswasfirstformallyexploredbyBritishmathematicianFrankRamsey(1903–1930).
ThisworkistodaycalledRamseyTheoryinhishonor.
Ourpartyresultreadsas.
(Drawsixdotsandcolortheedgesbetweenthenredandblue.
Eitheraredtriangleissuretoappearorablueone.
)Itisnothardtoseethat.
(Ifwedrawdotsonapageandcolortheedges,theneitheroneisredandwe'vefoundredcliqueofsizeoralledgesareblueandwehaveabluecliqueofsize.
Also,isnotorsmaller:coloringalltheedgesbetweendotsblueillustratesthis.
)JamesTanton2016www.
jamestanton.
comandwww.
gdaymath.
comComputingRamseynumbersisstillaveryactiveareaofresearch.
Onlythesefewvaluesarecurrentlyknown.
(Ofcourse,:justswitchcolors.
)Generalizing…Setastheleastnumberofdotsoneneedstodrawonthepagetoensurethat,incoloringtheedgesred,blueandgold,eitheracliqueofdotswithnothingbutrededgesbetweenthem,oracliqueofdotswithnothingbutblueedgesbetweenthem,oracliqueofdotswithnothingbutgoldedgesbetweenthemissuretoappear.
Itisknownthat.
(Draw17dotsonapageandcoloreachofthe153edgesbetweenthemeitherred,blue,orgold.
Thenamonochromatictriangleissuretoappear.
Also,itispossibletoavoidmonochromatictriangleswithonly16dotsonthepage.
)Andforfullgeneralitysetastheleastnumberofdotsoneneedstodrawonapagesothat,incoloringeachoftheedgesbetweenapairofdotsoneofcolors,thereissuretobeacliqueofdotswithalltheedgesbetweenthemthethcolor,forsome.
Ofcourse,weareassumingthatthisnumberexists-thatthereisaleastnumberofdotsthatassuresamonochromaticstructureappears.
Ramsey'sTheorem:Eachisindeedameaningfulfinitenumber.
Let'sillustratewhy.
ThevaluedoesnotappearonthelistofknownRamseynumbers.
Butwecanprovethatitisafinitenumber.
Wehave,fromthelist,and.
Drawdotsonthepageandcolortheedgesbetweenthemredandblue.
Weshallnowreasonthateitheracliqueofdotsexistswithalledgesbetweenthemredoracliqueofdotsexistswithalledgesbetweenthemblue.
Thiswillestablishthat.
Inourdiagramofdotswithedgescolored,chooseoneparticulardot.
CallitDilbert.
Dilberthassomerededgesemanatingfromitconnectingitto,say,otherdots.
TheremainingedgesemanatingfromDilbertareblue,connectingtootherdots,say.
Here.
Nowitcan'tbethatbothand.
Soeitherisatleastorisatleast.
Case:ConsiderthedotsthatconnecttoDilbertbyrededges.
Becausethereiseitheraredcliqueofamongthesedotsorthereisbluecliqueofamongthem.
Ifthereisaredcliqueof3,thenincludingDilbertintheclique(alledgestoDilbertarered)actuallymeanswehavearedcliqueof,oneofthetwostructureswearehopingtoseefor.
If,ontheotherhand,thereisabluecliqueof,thenwehaveabluecliqueof!
Eitherwaywehavefoundoneofthetwothingswearelookingfor.
JamesTanton2016www.
jamestanton.
comandwww.
gdaymath.
comCase:ConsiderthedotsthatconnecttoDilbertviablueedges.
Because,amongthesedotsthereiseitheraredcliqueof(oneofthepossibilitieswewerehopingfor)orabluecliqueof.
Inthelattercase,sincealltheedgestoDilberthereareblue,addingDilberttothecliqueoffiveactuallymakesabluecliqueof!
Again,wearesuretohaveatleastoneofthetwostructureswewerelookingfor.
Ingeneral,onecanprovejustthiswaytheinequality:.
ThenfromknowingthatRamseynumberswithsmallerindicesarefinitewecanreasonthateveryRamseynumberisfinite.
GeneralizedRamsey'sTheorem:Eachvalueisfinite.
Wehavejustshownthateachofthevaluesfortwocoloringsisafinitenumber.
Let'sshowhowwecanusethisfacttoestablishthateachofthenumbersforthreecoloringsmustalsobefinite.
Consider.
Wewanttoshowthatthereisanumbersothatifwedrawdotsonthepageandcolortheedgeseitherred,blue,orgold,thereissuretobeeitheraredcliqueofdots,orabluecliqueofdots,oragoldcliqueofdots.
Sometimeswhenwesquintoureyes,redandbluecanstarttoeachlookpurple.
Soadiagramwithedgespaintedwiththreecolors,red,blue,andgold,canlooklikeadiagramwithedgespaintedjusttwocolors,purpleandgold,undersquintyeyes.
Thisgivesawaytobringthree-coloringsbacktotwo-colorings.
Let.
(Soanydiagramofdotswithedgespaintedredandbluehaseitheraredcliqueofdotsorabluecliqueofdots.
)Let.
(Soanydiagramofdotswithedgespaintedpurpleorgoldhaseitherapurplecliqueofdotsoragoldcliqueofdots.
)Nowdrawdotsonthepageandcolortheedgesred,blue,andgold.
(Remember,wearelookingforeitheraredcliqueofdotsorabluecliqueofdotsoragoldcliqueofdots.
)Squintyoureyesandseeonlypurpleandgold.
Byourchoiceofwe'reeitherseeingapurplecliqueofdotsoragoldcliqueofdots.
Ifwe'reinthelattercase,thenwe'vefoundoneofthethreethingswewerehopingtosee.
Ifwe'reintheformercase,thenweareseeingapurplecliqueofdots,which,whenweunsquintoureyes,isasetofdotswithredandblueedgesbetweenthem.
Butourchoiceofwasspecial:itguaranteesthateitherwehavearedcliqueofdotsorabluecliqueofdots.
Soagain,weareseeingoneofthethreethingswewerehopingtosee.
Soisfiniteanumber:itisboundedbythenumberwith.
Ingeneral,onereasonsthiswaytoshowthatwith.
Nowknowingthatallthethree-colorRamseyvaluesarefinite,weJamesTanton2016www.
jamestanton.
comandwww.
gdaymath.
comcanusethistoarguethatallthefour-colorRamseynumbersarefinite,whichleadstoallthefive-colorRamseynumbersbeingfinite,andsoon.
CONNECTIONSTOTHEOPENINGPUZZLERHere'saboldclaim:Itisimpossibletocolorthecountingnumberseachoneoffiftypossiblecolorsandavoidamonochromatictriple,,.
(Thegenericcaseisallowed.
)(Thenumber50isimmaterialhere:anyfinitenumberofcolorswilldo!
)Here'swhy.
WejustprovedthattheRamseyvalue,withfiftycolors,isafinitevalue.
Letbeitsvalue.
Soifwedrawdotsonapageandcolortheedgesusingfiftydifferentcolors,thenwearesuretofindamonochromaticcliqueofthree.
Thatis,we'dfindamonochromatictriangle.
Supposewehavecoloredthecountingnumbers1,2,3,…eachoneoffiftycolors.
Drawadotaboveeachofthefirstcountingnumbersanddrawanedgebetweeneachpairdots.
Nowcoloreachedgeaccordingtothefollowingrule:Painttheedgeconnectingthenumbertothenumber(assumehere)withthecolorofnumber.
Amonochromatictriangleissuretoexist.
Fromthistrianglewehavethatthecolorofisthesamethecolorof,whichisthesameasthecolorof.
Butobserve:.
Wehavefoundthreenumbers,,andallthesamecolor.
Exercise:Coloreachpositiveintegeronecolorfromagivenfinitesetofcolors.
Musttherebeamonochromatictriple,,RESEARCHCORNER1.
Letbethesmallestvaluesothatifwecolortheeachofthenumberswithoneofcolorsthereissuretobeamonochromatic"triple".
(Wejustprovedthatexistsand,byeasyextension,thateachvalueexists.
)Wehaveand(ifyoudidthesecondpartoftheopeningexercise).
Canyoudetermineanyothervaluesof2.
Letbethesmallestvaluesothatifwecolortheeachofthenumberswithoneofcolorsthereissuretobeamonochromatictriple.
Wehaveand.
CanyouadjustthepreviousprooftoestablishthatthevaluesexistJamesTanton2016www.
jamestanton.
comandwww.
gdaymath.
com3.
Explorecoloringthepositiveintegerswithafinitepaletteofcolorsandestablishingtheexistenceofamonochromaticquadruple,,,,with.
2016JamesTantontanton.
math@gmail.
com
HostKvm也发布了开年促销方案,针对香港国际和美国洛杉矶两个机房的VPS主机提供7折优惠码,其他机房业务提供8折优惠码。商家成立于2013年,提供基于KVM架构的VPS主机,可选数据中心包括日本、新加坡、韩国、美国、中国香港等多个地区机房,均为国内直连或优化线路,延迟较低,适合建站或者远程办公等。下面列出几款主机配置信息。美国洛杉矶套餐:美国 US-Plan1CPU:1core内存:2GB硬盘...
国庆钜惠 最低5折起 限量促销CYUN专注海外精品服务器资源,主营香港CN2 GIA、美国CERA、美国高防服务器资源,实体公司,ISP/IDC资质齐全,客服配备齐全。本次针对国庆推出非常给力的促销活动,旗下所有平台同享,新老客户同享,限时限量,售完截止。活动截止时间:2021年10月9日官网地址:www.cyun.net参与机型:香港CN2 GIA云服务器、香港双程CN2云服...
cmivps香港VPS带来了3个新消息:(1)双向流量改为单向流量,相当于流量间接扩大一倍;(2)Hong Kong 2T、Hong Kong 3T、Hong Kong 无限流量,这三款VPS开始支持Windows系统,如果需要中文版Windows系统请下单付款完成之后发ticket要求官方更改即可;(3)全场7折年付、8折月付优惠,优惠码有效期一个月!官方网站:https://www.cmivp...
魔兽世界服务器维护为你推荐
php虚拟主机如何选择PHP网站虚拟主机域名注册申请怎么申请自己的域名?企业虚拟主机购买虚拟主机要注意些什么?企业网站有什么好的虚拟主机推荐吗?linux主机Linux主机 VS. Windows主机,您选择哪一个?网站域名怎么知道一个网站域名是什么啊!免费网站域名申请哪有里可以申请免费域名的网站?me域名me域名好不好用?虚拟主机申请域名申请以及虚拟主机台湾主机台湾的第一台电脑免备案虚拟空间免备案的虚拟主机空间,买了以后会强制备案不?
美国网站空间 中文域名查询 租服务器价格 vps代理 qq空间域名 域名备案号查询 128m内存 mediafire下载 密码泄露 长沙服务器 老左正传 徐正曦 cdn加速是什么 双线机房 空间购买 网站加速 乐视会员免费领取 广东服务器托管 japanese50m咸熟 windows2008 更多