2023年全國(guó)碩士研究生考試考研英語(yǔ)一試題真題（含答案詳解+作文范文）_第1頁(yè)
已閱讀1頁(yè)，還剩4頁(yè)未讀， 繼續(xù)免費(fèi)閱讀

下載本文檔

版權(quán)說(shuō)明：本文檔由用戶提供并上傳，收益歸屬內(nèi)容提供方，若內(nèi)容存在侵權(quán)，請(qǐng)進(jìn)行舉報(bào)或認(rèn)領(lǐng)

文檔簡(jiǎn)介

1、anoteofvariablesubstitution：變量替換一個(gè)音符：變量替換一個(gè)音符anoteofvariablesubstitution：變量替換一個(gè)音符ANoteofvariablesubstitutionIneachofthefmulasIhavegoneoverinchapters23eachvariableisexactlythatavariable.Avariableissomethingthatyoucansubst

2、ituteinanyvalueofthesimilartypef.thatiswhatmakesfmulaswithvariablessopowerful–theyareapplicabletoalargenumberofcases.HereisanexampleofwhatImean:TheDistributiveLawis:p(qr)(pq)(pr)Imaginesimplifyingthefollowingexpression:(

3、(st)v)(v(st))((st)v)((st)v)Commutative(st)(vv)Distributivewithp=stq=vr=v(st)FInverseLaw(st)IdentityLawOneotherthingtomention:noticehowIuseddifferentlettersintheproblemthanarelistedintherules.ThereasonIdidthatwasfclarity’

4、ssaketoshowyouallwhatwassubstitutedfeachvariable.BUTintheproblemsthatYOUdoyou’llfindthatpsqsrsareusedjustlikeinthefmula.Whenyoumakesubstitutionsyou’llhavetodifferentiatebetweenthep&qsfromthefmulathep&qsinyourspecificprob

5、lem!!!Becarefulwhendoingthis.Lastlectureweendedwiththeproblemofshowingthefollowing:(((AB)C)B)=(BC)Onewayistouseamembershiptable:ABCBC((AB)C)B(((AB)C)B)00001100010110010010001110011000110101001011001001111001elementxwemus

6、tshowthefollowing:ifxBthenxA.ToshowthiswesimplyassumethatxB.ButfrombefewealreadyKNOWthat($x|xAxB).WhatthismeansinEnglishisthatthereisNOelementthatbelongstobothAB.IfweknowthattheparticularelementxbelongsinBthenitCANNOTbel

7、onginA.SymbolicallywehavexA.ButwehavefallelementsthatxAxA.SincexAisfalsefromwhatwededucedaboveweMUSTHAVExAwhichisexactlywhatweneededtoprove.SowheneverAB=wehaveshownthatBAholds.UsingtheContrapositivefaproofLet’sconsiderpr

8、ovingthesamestatement.IfAB=thenBA.Thecontrapositiveofthisstatementisthefollowing:if(BA)then(AB=).Ifweprovethisstatementwehavealsoproventheiginalsinceastatementitscontrapositiveareequivalent.Sowewillassumethat(BA).Underth

9、isassumptionwemustshowthatAB.Ifwehavethat(BA)thenthereexistsanelementxsuchthatxisINBbutNOTINthecomplementofA.Symbolicallywehave:$x|xBxAIfwehaveanelementxAbydefinitionofcomplementwemusthavethatxA.Sowehave$x|xBxA.Butthisme

10、ansthatxAB!!!FromthatwecanconcludethatABasdesired.ProofbyContradictionMostofthiswilllookquitesimilartotheproofbefe.Inessencethereislittledifferencebetweenaproofbycontradictionaproofofthecontrapositive.Here’sthebasicidea:

溫馨提示

  • 1. 本站所有資源如無(wú)特殊說(shuō)明，都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請(qǐng)下載最新的WinRAR軟件解壓。
  • 2. 本站的文檔不包含任何第三方提供的附件圖紙等，如果需要附件，請(qǐng)聯(lián)系上傳者。文件的所有權(quán)益歸上傳用戶所有。
  • 3. 本站RAR壓縮包中若帶圖紙，網(wǎng)頁(yè)內(nèi)容里面會(huì)有圖紙預(yù)覽，若沒(méi)有圖紙預(yù)覽就沒(méi)有圖紙。
  • 4. 未經(jīng)權(quán)益所有人同意不得將文件中的內(nèi)容挪作商業(yè)或盈利用途。
  • 5. 眾賞文庫(kù)僅提供信息存儲(chǔ)空間，僅對(duì)用戶上傳內(nèi)容的表現(xiàn)方式做保護(hù)處理，對(duì)用戶上傳分享的文檔內(nèi)容本身不做任何修改或編輯，并不能對(duì)任何下載內(nèi)容負(fù)責(zé)。
  • 6. 下載文件中如有侵權(quán)或不適當(dāng)內(nèi)容，請(qǐng)與我們聯(lián)系，我們立即糾正。
  • 7. 本站不保證下載資源的準(zhǔn)確性、安全性和完整性, 同時(shí)也不承擔(dān)用戶因使用這些下載資源對(duì)自己和他人造成任何形式的傷害或損失。

評(píng)論

0/150

提交評(píng)論