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
触碰云怎么样?触碰云是一家成立于2019年的商家。触碰云主营香港/美国 VPS服务器、独立服务器以及免备案CDN。采用的是kvm虚拟构架,硬盘Raid10,Cn2线路,去程电信CN2、移动联通直连,回程三网CN2。最低1核1G带宽1M仅20.8元/月,不过这里推荐香港4核4G15M,香港cn2 gia线路云服务器,仅115.2元/月起,性价比还是不错的。点击进入:触碰云官方网站地址触碰云优惠码:优...
很久没有分享PhotonVPS的消息,最近看到商家VPS主机套餐有一些更新所以分享下。这是一家成立于2008年的国外VPS服务商,Psychz机房旗下的站点,主要提供VPS和独立服务器等,数据中心包括美国洛杉矶、达拉斯、芝加哥、阿什本等。目前,商家针对Cloud VPS提供8折优惠码,优惠后最低2G内存套餐每月4美元起。下面列出几款主机配置信息。CPU:1core内存:2GB硬盘:30GB NVm...
美国知名管理型主机公司,2006年运作至今,虚拟主机、VPS、云服务器、独立服务器等业务全部采用“managed”,也就是人工参与度高,很多事情都可以人工帮你处理,不过一直以来价格也贵。也不知道knownhost什么时候开始运作无管理型业务的,估计是为了扩展市场吧,反正是出来较长时间了。闲来无事,那就给大家介绍下“unmanaged VPS”,也就是无管理型VPS,低至5美元/月,基于KVM虚拟,...
魔兽世界服务器维护为你推荐
已备案域名查询已经有个顶级域名,怎么查询是否备案?海外主机那些韩国主机,美国主机是怎么来的?独立ip虚拟主机独立ip空间的虚拟主机一般多少钱虚拟主机管理系统急!高分!比较好用的虚拟主机管理系统有哪些?windows虚拟主机在windows上怎么安装虚拟机m3型虚拟主机建网站,M型虚拟主机和G型虚拟主机,选哪种好?域名批量查询如何进行域名批量查询注册域名抢注在网上怎样抢注域名?域名系统DNS域名系统的特点是什么域名论坛论坛域名怎么看
ip查域名 最便宜的vps 3322免费域名 互联网域名管理办法 187邮箱 omnis sub-process 香港新世界电讯 免费个人空间 idc资讯 169邮箱 百度云1t 台湾google 国外在线代理服务器 国内域名 游戏服务器出租 主机返佣 免 windowsserver2008 web服务器 更多