CPSC 121: Models of Computation - University of British ...cs121/2016W2/slides/gao/0... · CPSC...
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1 1/4/17 1 CPSC 121: Models of Computation Section 202 Mondays, Wednesdays and Fridays 10am to 11am Geography 100 CPSC121 – 2016W2 1 CPSC 121: Models of Computation Module 0: Course Introduction CPSC121 – 2016W2 2 Who am I? • Alice Gao ([email protected]) • Postdoctoral fellow in Computer Science • PhD in Computer Science at Harvard University • Undergrad in CPSC and MATH at UBC • www.cs.ubc.ca/~xigao/ • ICICS X563; office hours TBD on the website. CPSC121 – 2016W2 3 Introduce yourself to your neighbours! • You will work in pairs for labs and assignments. • Maybe you can find a partner now. CPSC121 – 2016W2 4
Transcript of CPSC 121: Models of Computation - University of British ...cs121/2016W2/slides/gao/0... · CPSC...
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CPSC121:ModelsofComputation
Section202
Mondays,WednesdaysandFridays10amto11am
Geography100
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CPSC121:ModelsofComputation
Module0:CourseIntroduction
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WhoamI?
•AliceGao([email protected])
•PostdoctoralfellowinComputerScience•PhDinComputerScienceatHarvardUniversity•UndergradinCPSCandMATHatUBC•www.cs.ubc.ca/~xigao/
• ICICSX563;officehoursTBDonthewebsite.
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Introduceyourselftoyourneighbours!
•Youwillworkinpairsforlabsandassignments.•Maybeyoucanfindapartnernow.
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Today'slearninggoals
Bytheendofthismodule,youshouldbeableto:•Giveanexampleofhowwecanapplyformalreasoningtoasimple,real-worldtask.
•Giveanexampleofhowacomputationalsolutiontothissimpletaskmightgowrong.
•Describethefour“bigquestions”thatwewillstartansweringinCPSC121.
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Let'strysorting
Activity:analgorithmtoorderstudentsbydayofbirth.
Howmanyswapsdidyouneedtomake?
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Jan 1st Feb 24th Jul 24th Jul 31st Sept 18th
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Computingn(n-1)/2
Computing n(n-1)/2usingDr.Racket:
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Computingn(n-1)/2[continued]
Computing n(n-1)/2usingJava:
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import java.io.*;
public class Compute{
public static void main(String[] args){
int n = Integer.parseInt(args[0]);System.out.println(n * (n-1) / 2);
}}
poirot> java Compute 510
poirot> java Compute 1000499500
poirot> java Compute 1000000-364189984
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Questionstoponder:
•Howcanweprovethatn(n-1)/2isthelargestnumberofswapsneededfornbirthdays?
DirectProoforMathematicalInduction•WhydidourJavaimplementationprintanegativevalue,butnottheRacketimplementation?
Numberrepresentation
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CPSC121:TheBIG questions
1. Howcanweconvinceourselvesthatanalgorithmdoeswhatit'ssupposedtodo?
2. Howdowedeterminewhetherornotonealgorithmisbetterthananotherone?
3. Howdoesthecomputer(e.g.Dr.Racket)decideifthecharactersofyourprogramrepresentaname,anumber,orsomethingelse?Howdoesitfigureoutifyouhavemismatched""or()?
4. Howcanwebuildacomputerthatisabletoexecuteauser-definedprogram?
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Aworkingcomputer
Aworkingcomputeryouwilllearnaboutinthelabs:
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Explorethewebsite
•http://www.ugrad.cs.ubc.ca/~cs121/current/•Youarerequired tobefamiliarwiththecoursewebsite.Ignoranceofinformationonthewebsitemayharmyou.
•Attheminimum,readeverythinginthe“courseinfo”section,skimmingthedetailedlearninggoals.
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Gradingscheme
Yourfinalgradewillbecomputedasfollows:•Assignments(5):14%•Labs(9):14%•Pre-classquizzes(10):5%•Midterms(2):24%
•MondayFebruary6th,2017,7pm•MondayMarch20th,2017,7pm
•FinalExam:40%• In-classparticipation/clickers:3%
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Lecturetopics
•Mylectureswillfollowtopicslistedunder“LearningGoalsandReadings”onthecoursewebsite.
•Thepagealsocontainstherequiredreadingsforeachlecture.
•http://www.ugrad.cs.ubc.ca/~cs121/2016W2/index.php?page=topics&menu=0&submenu=3
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Pre-classquizzes
•TheyarepostedonConnect.•ThereadingsareonConnectandalsounder“LearningGoalsandReadings”onthecoursewebsite.
•Thefirstquizisduetomorrowevening(Thursday)at7pm.Wewilldoubleyourmarkonthefirstquiztoamaxof100%(Ifyouearnmorethan50%,itwillcountas100%.).
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Courseactivities
•ThescheduleforlabsandtutorialsisunderLabsonthecoursewebsite.
•Labs:• Startnextweek(onMondayJan9th,2016).• Youmust attendthelabyouareregisteredfor.• Pre-labworkmustbedonebefore yougettothelab.
•Tutorials:• Startnextweek (onMondayJan9th,2016).• Try toattendthetutorialyouareregisteredfor.
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Courseactivities[continued]
•Piazza:• Fordiscussions.• https://piazza.com/ubc.ca/winterterm22016/cpsc121• Toregister,usetheaccesscode:[tobeannouncedinclass]
•AcademicConduct:• Pleasereadtherulesonthecoursewebsiteandfollowthem.
•Notfollowingtheseruleswillbeunpleasantforallofus.
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Courselearningoutcomes
Afteryoucompletethecourse,youwillbeableto:•modelimportantproblemssothattheyareeasiertodiscuss,reasonabout,solve,andtest.
• learnnewmodelingformalismsmoreeasily.• communicateclearlyandunambiguouslywithotherCSexpertsoncomplextopics.
• characterizealgorithms(CSproblemsolutions),byprovingtheircorrectnessorefficiency.
• criticallyreadproofs:justifyingwhyeachstepiscorrectandjudgingwhattheproofmeans.
• explainhowcomputerswork.
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Firstpre-classquiz
•Firstpre-classquiz:duetomorrow(Thursday)at7pm.
•Sectionstoreadforthequiz(readoneofthem):• Epp,4thedition:2.1and2.4.• Epp,3rdedition:1.1and1.4
•Thereadingsareunder“LearningGoalsandReadings”onthecoursewebsite.
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