General Computer Science 320201 GenCS I & II Lecture ... - Kwarc

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Port use comment 22 SSH remote shell 53 DNS Domain Name System 80 HTTP World Wide Web 443 HTTPS HTTP over SSL c○: Michael Kohlhase 345 On top of the transport-layer services, we can define even more specific services. From the perspective of the internet protocol suite this layer is unregulated, and application-specific. From a user perspective, many useful services are just “applications” and live at the application layer. The Application Layer Definition 506 The application layer of the internet protocol suite contains all protocols and methods that fall into the realm of process-to-process communications via an Internet Protocol (IP) network using the Transport Layer protocols to establish underlying host-to-host connections. Example 507 (Some Application Layer Protocols and Services) BitTorrent Peer-to-peer Atom Syndication DHCP Dynamic Host Configuration DNS Domain Name System FTP File Transfer Protocol HTTP HyperText Transfer IMAP Internet Message Access IRCP Internet Relay Chat NFS Network File System NNTP Network News Transfer NTP Network Time Protocol POP Post Office Protocol RPC Remote Procedure Call SMB Server Message Block SMTP Simple Mail Transfer SSH Secure Shell TELNET Terminal Emulation WebDAV Write-enabled Web c○: Michael Kohlhase 346 We will now go into the some of the most salient services on the network application layer. The domain name system is a sort of telephone book of the Internet that allows us to use symbolic names for hosts like kwarc.info instead of the IP number 212.201.49.189. Domain Names Definition 508 The DNS (Domain Name System) is a distributed set of servers that provides the mapping between (static) IP addresses and domain names. Example 509 e.g. www.kwarc.info stands for the IP address 212.201.49.189. Definition 510 Domain names are hierarchically organized, with the most significant part (the top-level domain TLD) last. networked computers can have more than one DNS name. (virtual servers) 197
Domain names must be registered to ensure uniqueness (registration fees vary, cybersquatting) Definition 511 ICANN is a non-profit organization was established to regulate humanfriendly domain names. It approves top-level domains, and corresponding domain name registrars and delegates the actual registration to them. c○: Michael Kohlhase 347 Let us have a look at a selection of the top-level domains in use today. Domain Name Top-Level Domains .com (“commercial”) is a generic top-level domain. It was one of the original top-level domains, and has grown to be the largest in use. .org (“organization”) is a generic top-level domain, and is mostly associated with non-profit organizations. It is also used in the charitable field, and used by the open-source movement. Government sites and Political parties in the US have domain names ending in .org .net (“network”) is a generic top-level domain and is one of the original top-level domains. Initially intended to be used only for network providers (such as Internet service providers). It is still popular with network operators, it is often treated as a second .com. It is currently the third most popular top-level domain. .edu (“education”) is the generic top-level domain for educational institutions, primarily those in the United States. One of the first top-level domains, .edu was originally intended for educational institutions anywhere in the world. Only post-secondary institutions that are accredited by an agency on the U.S. Department of Education’s list of nationally recognized accrediting agencies are eligible to apply for a .edu domain. .info (“information”) is a generic top-level domain intended for informative website’s, although its use is not restricted. It is an unrestricted domain, meaning that anyone can obtain a second-level domain under .info. The .info was one of many extension(s) that was meant to take the pressure off the overcrowded .com domain. .gov (“government”) a generic top-level domain used by government entities in the United States. Other countries typically use a second-level domain for this purpose, e.g., .gov.uk for the United Kingdom. Since the United States controls the .gov Top Level Domain, it would be impossible for another country to create a domain ending in .gov. .biz (“business”) the name is a phonetic spelling of the first syllable of “business”. A generic top-level domain to be used by businesses. It was created due to the demand for good domain names available in the .com top-level domain, and to provide an alternative to businesses whose preferred .com domain name which had already been registered by another. .xxx (“porn”) the name is a play on the verdict “X-rated” for movies. A generic top-level domain to be used for sexually explicit material. It was created in 2011 in the hope to move sexually explicit material from the “normal web”. But there is no mandate for porn to be restricted to the .xxx domain, this would be difficult due to problems of definition, different jurisdictions, and free speech issues. c○: Michael Kohlhase 348 Note: Anybody can register a domain name from a registrar against a small yearly fee. Domain names are given out on a first-come-first-serve basis by the domain name registrars, which usually also offer services like domain name parking, DNS management, URL forwarding, etc. The next application-level service is the SMTP protocol used for sending e-mail. It is based on 198
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General Computer Science 320201 Gen
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Java programmer” on the practical
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Contents 1 Preface i 2 Representati
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4 Search and Declarative Computatio
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Fundamental Algorithms and Data str
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To earn an audit you have to take t
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i.e. to function as a member of the
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a factor two in speed. This ability
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“Applets, Not Craplets tm ” (-
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c○: Michael Kohlhase 17 Can be re
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Example 10 (Kruskal’s algorithm,
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n 100n µs 7n 2 µs 2 n µs 1 100
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2.2 Elementary Discrete Math 2.2.1
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Axiom 19 (P 1) “ ” (aka. “zer
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Theorem 36 is a very useful fact to
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Definition 43 The unary product ope
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y stating element-hood (a ∈ S) or
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Idea: We need a notion of “counti
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Example 64 On sets of persons, the
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Definition 82 We say that a set A i
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clean enough to learn important con
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Definition 90 anonymous variables (
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c○: Michael Kohlhase 66 Defining
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- fun both_plus (x:int,y:int) = fn
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+(〈n, o〉) = n (base) and +(〈m
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the axiom says that any object that
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epresent them as a data type, where
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Example 127 〈{N}, {[o: N], [s: N
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The central idea here is what we ha
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Substitutions Definition 149 Let A
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Idea: Well-formed parts of construc
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Other programming languages chose a
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generally: fn+1 := fn + fn−1 plus
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input/output: the interesting bit a
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exception NaN; (* Not a Number *) f
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Example 191 If A = {a, b, c}, then
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Example 210 The Morse Code in the t
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The first 32 characters are control
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Idea: Unicode supports multiple enc
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2.5 Boolean Algebra We will now loo
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What a mess! Iϕ((x1 + x2) + (x1
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c○: Michael Kohlhase 140 The defi
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(f ≤a g), iff there is an n0 ∈
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P.1.2.3 then there are ei ∈ Ebool
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2.5.4 The Quine-McCluskey Algorithm
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the disjunctive normal form, and th
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Proof: by contradiction: let p /∈
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So, the minimal polynomial of f is
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2.6 Propositional Logic 2.6.1 Boole
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Idea: Import semantics from Boolean
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which we can always do, since we ha
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e quite difficult to establish in g
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H 0 axioms are valid Lemma 316 The
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c○: Michael Kohlhase 188 The enta
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The deduction theorem and the entai
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Inference with local hypotheses [A
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2.7 Machine-Oriented Calculi Now we
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Thus the tableau procedure can be u
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A ∨ BT AT BT A ⇒ BT AF BT
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Proof: P.1 It is easy to see tahat
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(P ⇒ Q ⇒ R) ⇒ (P ⇒ Q) ⇒ P
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⎧ ⎪⎨ We represented the maze
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defined a directed graph to be a se
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Paths in Graphs Definition 373 Giv
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This allows us to view Boolean expr
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Computing with Combinational Circui
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Corollary 399 A fully balanced tree
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X 1 X 2 X 3 X n = if L i =X i if L
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3.2 Arithmetic Circuits 3.2.1 Basic
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S S ψ ψ −1 fS = ψ −1 ◦ fT
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The Full Adder Definition 415 The
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first summand 3 4 7 9 8 3 4 7 9 2 s
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c○: Michael Kohlhase 249 The anal
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Problems of Sign-Bit Systems Gener
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generate the n-bit binary number re
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and an + bn + (icn(a, b, c)) = 〈
Page 153 and 154: Summary: We have built a combinatio
Page 155 and 156: To understand the operation of the
Page 157 and 158: Example 443 (Address decoder logic
Page 159 and 160: 3.4 Computing Devices and Programmi
Page 161 and 162: Our notion of time is in this const
Page 163 and 164: instructions LOADIN 1 and LOADIN 2
Page 165 and 166: Definition 457 An ASM program VM is
Page 167 and 168: instruction effect VPC peek i push
Page 169 and 170: c○: Michael Kohlhase 289 With the
Page 171 and 172: Imperative Stack Operations: peek l
Page 173 and 174: A SW program (see the next slide fo
Page 175 and 176: arguments to arithmetic operations
Page 177 and 178: µML, a very simple Functional Prog
Page 179 and 180: call pushes the return address (of
Page 181 and 182: [proc 2 26, con 0, arg 2, leq, cjp
Page 183 and 184: [proc 2 26, con 0, arg 2, leq, cjp
Page 185 and 186: eturn takes the current frame from
Page 187 and 188: label instruction effect comment
Page 189 and 190: Compiling µML Expressions (Continu
Page 191 and 192: c○: Michael Kohlhase 325 We want
Page 193 and 194: State Machine: 1 1,R 1 1,R 1 1,L 1
Page 195 and 196: The coded description acts as a pro
Page 197 and 198: the turing function uses will_halt
Page 199 and 200: Terabyte (T B) 1,000,000,000,000 by
Page 201 and 202: Layers in TCP/IP: TCP/IP uses encap
Page 203: name comment 4 version IPv4 or IPv6
Page 207 and 208: That was almost all, but we close t
Page 209 and 210: c○: Michael Kohlhase 353 Note tha
Page 211 and 212: Definition 529 HTTP is used by a cl
Page 213 and 214: structure html,head, body metadata
Page 215 and 216: Server-Side Scripting: Programming
Page 217 and 218: c○: Michael Kohlhase 367 Indeed,
Page 219 and 220: presentation tools), but can also i
Page 221 and 222: 1. reads web page 2. reports it hom
Page 223 and 224: Definition 570 Let A be a web page
Page 225 and 226: can combine both to falsify communi
Page 227 and 228: Candidates for one-way/trapdoor fun
Page 229 and 230: on a UNIX system, you can create a
Page 231 and 232: conceptually: transfer of directed
Page 233 and 234: Definition 591 The XML path languag
Page 235 and 236: Resources: Globally Identified by U
Page 237 and 238: R⌉}〉∫⊔⌉∇⌉⌈√⊣∇
Page 239 and 240: Problem solving Problem: Find algo
Page 241 and 242: Single-state Problem: Start in 5
Page 243 and 244: States integer locations of tiles A
Page 245 and 246: Implementation: States vs. nodes A
Page 247 and 248: Breadth-First Search c○: Michael
Page 249 and 250: Breadth-First Search: Romania c○:
Page 251 and 252: Note: Equivalent to breadth-first s
Page 253 and 254: A B C D E F G H I J K L M N O Depth
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A B C D E F G H I J K L M N O Depth
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Iterative deepening search Depth-l
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Breadth-first search Iterative deep
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Sibiu 253 Greedy Search: Romania Ar
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P.2 Let n be an unexpanded node on
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A ∗ search: Properties Complete Y
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Definition 618 (n-queens problem) P
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escape certain odd phenomena occurr
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GAs = evolution: e.g., real genes e
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Definition 632 A query is a list of
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(autoload ’run-prolog "prolog" "S
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Example 638 Computing the the n th
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Deduction: knowledge extension Abd
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[Koh06] Michael Kohlhase. OMDoc - A
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astarSearch search, 255 asymmetric-
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infinite, 32 counter program, 152,
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functional variable, 170 gate, 122
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media access control address, 194 M
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procedure abstract, 54 procedure de
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function, 30 spanning tree, 13 spro
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name, 70 variable functional, 170 v
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General Computer Science 320201 GenCS I & II Lecture ... - Kwarc

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