Slide 1What is Computer Science?Slide 3Slide 4Slide 5What is the difference between Euclid and Ada?Geometry vs. Computer ScienceComputer ScienceScience, Engineering, Other?Science?Engineering?Apollo Guidance Computer, 1969Measuring ComputersHow much power?Computing Power 1969-2008 (in Apollo Control Computer Units)Constraints Computer Scientists FaceSo, what is computer science?Liberal Arts: ~1100The Liberal ArtsCourse ExpectationsCourse RoadmapLike Drinking from a FirehoseBooksHelp AvailableWhat I Expect of YouBackground ExpectedA Course for Everyone!First Main Theme: Recursive DefinitionsSlide 29According to GuinnessMaking Longer WordsLanguage is RecursiveRecursive DefinitionsSlide 34ChargeThanks!1CS150 Fall 2005: 1. IntroductionDavid Evanshttp://www.cs.virginia.edu/evansCS150 Spring 2007University of VirginiaComputer ScienceClass 1: Class 1: IntroductionIntroduction21. IntroductionWhat is Computer Science?31. IntroductionLet AB and CD be the two given numbers not relatively prime. It is required to find the greatest common measure of AB and CD.If now CD measures AB, since it also measures itself, then CD is a common measure of CD and AB. And it is manifest that it is also the greatest, for no greater number than CD measures CD. Euclid’s Elements, Book VII, Proposition 2 (300BC)41. IntroductionThe note on the inflected line is only difficult to you, because it is so easy. There is in fact nothing in it, but you think there must be some grand mystery hidden under that word inflected! Whenever from any point without a given line, you draw a long to any point in the given line, you have inflected a line upon a given line.Ada Byron (age 19), letter to Annabella Acheson (explaining Euclid), 183451. IntroductionBy the word operation, we mean any process which alters the mutual relation of two or more things, be this relation of what kind it may. This is the most general definition, and would include all subjects in the universe... Supposing, for instance, that the fundamental relations of pitched sounds in the science of harmony and of musical composition were susceptible of such expression and adaptations, the engine might compose elaborate and scientific pieces of music of any degree of complexity or extent.Ada Byron, 184361. IntroductionWhat is the difference between Euclid and Ada?“It depends on what your definition of ‘is’ is.” Bill Gates (at Microsoft’santi-trust trial)71. IntroductionGeometry vs. Computer Science•Geometry (mathematics) is about declarative knowledge: “what is” If now CD measures AB, since it also measures itself, then CD is a common measure of CD and AB•Computer Science is about imperative knowledge: “how to”Computer Science has little to do with beige (or translucent blue) boxes called “computers” and is not a real science.81. IntroductionComputer Science“How to” knowledge:•Ways of describing information processes (computations)•Ways of predicting properties of information processes LanguageLogicWhat kinds of things do we want to predict?91. IntroductionScience, Engineering, Other?101. IntroductionScience?•Understanding Nature through Observation–About real things like bowling balls, black holes, antimatter, electrons, comets, etc.•Math and Computer Science are about fake things like numbers, graphs, functions, lists, etc.–Computer Science is a useful tool for doing real science, but not a real science111. IntroductionEngineering?“Engineering is design under constraint… Engineering is synthetic - it strives to create what can be, but it is constrained by nature, by cost, by concerns of safety, reliability, environmental impact, manufacturability, maintainability and many other such 'ilities.' ...” William Wulf121. IntroductionApollo Guidance Computer, 19691 Cubic FootWhy did they need to fit the guidance computer in the rocket?131. IntroductionMeasuring Computers•1 bit = smallest unit of information–True or False–0 or 1–If we start with 2 possible choices, and get 1 bit, we can eliminate one of the choices141. IntroductionHow much power?•Apollo Computer: 30720 bits of changeable memory •Lab machines have 1 GB (RAM)–1 Gigabyte = 1024 Megabytes, 1 Megabyte = 1024 Kilobytes, 1 Kilobyte = 1024 Bytes, 1 Byte = 8 bits> (* 1024 1024 1024 8)8589934592 ~ 8.6 Billion bits> (round (/ (* 1024 1024 1024 8) 30720))279620If Apollo Guidance Computer power is 1 inch, you have 4.4 miles!You have 105 404 times more power than AGCYou will understand thisnotation soon…but don’t worryif you don’t now15CS150 Fall 2005: 1. IntroductionComputing Power 1969-2008(in Apollo Control Computer Units)Moore’s “Law”: computing power roughly doubles every 18 months!161. IntroductionConstraints Computer Scientists Face•Not like those for engineers:–Cost, weight, physics, etc.–If ~20 Million times what people had in 1969 isn’t enough for you, wait until 2010 and you will have 80 Million times…•More like those for Musicians and Poets:–Imagination and Creativity–Complexity of what we can understand171. IntroductionSo, what is computer science?•Science–No: its about fake things like numbers, not about observing and understanding nature •Engineering–No: we don’t have to deal with engineering-type constraints•Liberal Art181. IntroductionLiberal Arts: ~1100•Illiberal Arts–arts for the non-free: pursued for economic reasons•Liberal Arts–arts for the free: pursued for intrinsic reasons191. IntroductionThe Liberal ArtsTrivium (3 roads)languageQuadrivium (4 roads)numbersGrammarstudy of meaning in written expressionRhetoriccomprehension of discourseLogicargument for discovering truthArithmeticGeometryquantification of spaceMusicnumber in timeAstronomyWe will see all of these in this class!201. IntroductionCourse Expectations211. IntroductionCourse RoadmapComputer Science from Euclid and Ada to Quantum Computing and the World Wide Web1st ClassPS 7-8Lecture PS 1-6Liberal Arts(Intellectual)Illiberal Arts($$$$)221. IntroductionLike Drinking from a FirehoseIt may hurt a little bit, and a lot of water will go by you, but you won’t go away thirsty!Don’t be overwhelmed!You will do fine.231. IntroductionBooksComputational Thinking A Whirlwind Introduction to the Third Millennial Liberal Art from Ada and Euclid to Quantum Computing and the World Wide Web“GEB”New Book!: written for courseChapters 2 and 3 out todayBonuses for helping me improve it: - Less pretentious title (?) - More exciting