CS 154. Time Complexity: P and NP. Complexity Theory. Measuring Time Complexity. A = { 0 k 1 k k 0 } TIME(n log n) Time-Bounded Complexity Classes
|
|
- Jason Dalton
- 7 years ago
- Views:
Transcription
1 CS 154 Time Complexity: P and NP Complexity Theory Study of what can and can t be computed with limited resources on computation, such as time, space, and so on We ll start with: Time complexity Measuring Time Complexity We measure time complexity by counting the elementary steps required for a machine to halt Consider the language A = { 0 k 1 k k 0 } On input of length n: 1. Scan across the tape and reject if the ~n string is not of the form 0 i 1 j ~n 2 ~n 2. Repeat the following if both 0s and 1s remain on the tape: Scan across the tape, crossing off a single 0 and a single 1 3. If 0s remain after all 1s have been crossed off, or vice-versa, reject. Otherwise accept. Let M be a TM that halts on all inputs. Definition: The running time or time complexity of M is the function f : N N such that f(n) = maximum number of steps taken by M over any input of length n. Time-Bounded Complexity Classes Definition: TIME(t(n)) = { L there is a Turing machine M with time complexity O(t(n)) so that L =L(M) } = {L L is a language decided by a Turing Machine with O(t(n)) running time } We showed: A = { 0 k 1 k k 0 } TIME(n 2 ) A = { 0 k 1 k k 0 } TIME(n log n) M(w) := If w is not of the form 0*1*, reject. Repeat until all bits of w are crossed out: If the parity of 0 s parity of 1 s, reject. Cross out every other 0. Cross out every other 1. Otherwise, accept x0x0x0x0x0x0xx1x1x1x1x1x1x xxx0xxx0xxx0xxxx1xxx1xxx1x xxxxxxx0xxxxxxxxxxxx1xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx 1
2 Theorem: A = { 0 k 1 k k 0 } can be decided in O(n) time with a two-tape TM. Proof Idea: Scan all 0s, copy them to the second tape. Scan all 1s. For each 1 scanned, cross off a 0 from the second tape. Different models of computation can yield different running times for the same language! Theorem: Every Multitape Turing Machine can be transformed into a single tape Turing Machine Theorem: Let t(n) be a function such that t(n) n. Then every t(n) time multi-tape TM has an equivalent O(t(n) 2 ) single tape TM Our simulation of multitape TMs achieved this! T(n) time FINITE STATE CONTROL T(n) 2 time FINITE STATE CONTROL # # # Time Hierarchy Theorem Intuition: If you get more time to work, then you can solve strictly more problems Theorem: For reasonable f, g : N N where f(n) = O(g(n) 1/3 ), TIME(f(n)) TIME(g(n)) Proof Idea: Diagonalization! Make a TM N that does the opposite of all g(n) 1/3 time machines on at least one input, and runs in O(g(n)) time So L(N) is in TIME(g(n)) but not in TIME(f(n)) Time Hierarchy Theorem Theorem: For reasonable f, g where f(n) = O(g(n) 1/3 ) TIME(f(n)) TIME(g(n)) Proof Sketch: Define a machine N as follows. N(w) = If w is not equal to M10 i for some M, i, reject Simulate M on w for f( w ) steps (This simulation itself uses f( w ) 2 time) If M tries to take more time, reject Accept if and only if M has rejected Eventually, w is large enough that f( w ) < g( w ) Simulation can be carried out using multitape sim. Need to compute f( w ) using only O(g( w )) time 2
3 Time Hierarchy Theorem Theorem: For reasonable f, g where f(n) = O(g(n) 1/3 ) TIME(f(n)) TIME(g(n)) Corollary: TIME(n) TIME(n 2 ) TIME(n 4 ) There is an infinite hierarchy of increasingly more time-consuming problems P = TIME(n k ) k N Question: Are there important everyday problems that are high up in the hierarchy? A natural problem that needs exactly n 10 time? THIS IS AN OPEN QUESTION! The EXTENDED Church-Turing Thesis Everyone s Intuitive Notion = Polynomial-Time of Efficient Turing Machines Algorithms Nondeterminism and NP Much more controversial. Potential counterexamples include n 100 time algorithms, Quantum & Randomized algorithms Nondeterministic Turing Machines read write move 0 0, R are just like standard TMs, except: 0 0, R, R q accept 1. The machine may proceed according to several possibilities, R q reject 0 0, R 2. The machine accepts a string if there exists a path from start configuration to an accepting configuration 3
4 Definition: A nondeterministic TM is a 7-tuple T = (Q, Σ, Γ, δ, q 0, q accept, q reject ), where: Q is a finite set of states Σ is the input alphabet, where Σ Γ is the tape alphabet, where Γand Σ Γ δ : Q Γ 2 (Q Γ {L,R}) q 0 Q is the start state q accept Q is the accept state q reject Q is the reject state, and q reject q accept Deterministic Computation accept or reject Nondeterministic Computation accept reject Defining Acceptance for NTMs Let N be a nondeterministic Turing machine An accepting computation history for N on w is a sequence of configurations C 0,C 1,,C t where 1. C 0 is the start configuration q 0 w, 2. C t is an accepting configuration, 3. Each configuration C i yields C i+1 N(w) accepts in t time iff such a history exists. Accepting computation histories for N on w do not have to be unique! Definition: NTIME(t(n)) = { L L is decided by a O(t(n)) time nondeterministic Turing machine } TIME(t(n)) NTIME(t(n)) Is this a proper containment for all t(n)? THIS IS AN OPEN QUESTION! A Boolean formula is satisfiable if there exists a satisfying assignment for it A 3cnf-formula has the form: (x 1 x 2 x 3 ) (x 4 x 2 x 5 ) (x 3 x 2 x 1 ) YES NO a b c d (x y) x SAT = { φ φ is a satisfiable Boolean formula } literals clauses (x 1 x 2 x 1 ) (x 3 x 1 ) (x 3 x 2 x 1 ) (x 1 x 2 x 3 ) ( x 4 x 2 x 1 ) (x 3 x 1 x 1 ) (x 1 x 2 x 3 ) (x 3 x 2 x 1 ) 3SAT = { φ φ is a satisfiable 3cnf-formula } 4
5 3SAT = { φ φ is a satisfiable 3cnf-formula } Theorem: 3SAT NTIME(n 2 ) On input φ: 1. Check if the formula is in 3cnf 2. For each variable, nondeterministically substitute it with 0 or 1 ( x y x ) NP = NTIME(n k ) k N ( 0 y 0 ) ( 1 y 1 ) ( ) ( ) 3. Test if the assignment satisfies φ Theorem: L NP there is a poly-time Turing machine V and k such that we can define L as: L = { x y [ y x k and V(x,y) accepts ] } Proof: (1) If L = { x y y x k and V(x,y) accepts } then L NP Nondeterministically guess y and then run V(x,y) (2) If L NP then L = { x y y x k and V(x,y) accepts } 3SAT = { φ y such that y is a satisfying assignment to φ and φ is in 3cnf } SAT = { φ y such that y is a satisfying assignment to φ } Let N be a nondeterministic poly-time TM that decides L. Define V(x,y) to accept iff y is an accepting computation history of N on x The Hamiltonian Path Problem A language is in NP if and only if there are polynomial-length proofs for membership to the language b a e d f g SAT is in NP because a satisfying assignment is a polynomial-length proof that a formula is satisfiable i A Hamiltonian path traverses through each node exactly once c h 5
6 Assume a reasonable encoding of graphs (example: the adjacency matrix is reasonable) HAMPATH = { (G,s,t) G is a directed graph with a Hamiltonian path from s to t } Theorem: HAMPATH NP Next Episode: NP-Complete Problems The Hamiltonian path is a proof that (G,s,t) is a member of HAMPATH 6
CS154. Turing Machines. Turing Machine. Turing Machines versus DFAs FINITE STATE CONTROL AI N P U T INFINITE TAPE. read write move.
CS54 Turing Machines Turing Machine q 0 AI N P U T IN TAPE read write move read write move Language = {0} q This Turing machine recognizes the language {0} Turing Machines versus DFAs TM can both write
More informationTheoretical Computer Science (Bridging Course) Complexity
Theoretical Computer Science (Bridging Course) Complexity Gian Diego Tipaldi A scenario You are a programmer working for a logistics company Your boss asks you to implement a program that optimizes the
More informationDiagonalization. Ahto Buldas. Lecture 3 of Complexity Theory October 8, 2009. Slides based on S.Aurora, B.Barak. Complexity Theory: A Modern Approach.
Diagonalization Slides based on S.Aurora, B.Barak. Complexity Theory: A Modern Approach. Ahto Buldas Ahto.Buldas@ut.ee Background One basic goal in complexity theory is to separate interesting complexity
More informationNotes on Complexity Theory Last updated: August, 2011. Lecture 1
Notes on Complexity Theory Last updated: August, 2011 Jonathan Katz Lecture 1 1 Turing Machines I assume that most students have encountered Turing machines before. (Students who have not may want to look
More informationTheory of Computation Chapter 2: Turing Machines
Theory of Computation Chapter 2: Turing Machines Guan-Shieng Huang Feb. 24, 2003 Feb. 19, 2006 0-0 Turing Machine δ K 0111000a 01bb 1 Definition of TMs A Turing Machine is a quadruple M = (K, Σ, δ, s),
More informationLecture 2: Universality
CS 710: Complexity Theory 1/21/2010 Lecture 2: Universality Instructor: Dieter van Melkebeek Scribe: Tyson Williams In this lecture, we introduce the notion of a universal machine, develop efficient universal
More information3515ICT Theory of Computation Turing Machines
Griffith University 3515ICT Theory of Computation Turing Machines (Based loosely on slides by Harald Søndergaard of The University of Melbourne) 9-0 Overview Turing machines: a general model of computation
More informationThe Classes P and NP
The Classes P and NP We now shift gears slightly and restrict our attention to the examination of two families of problems which are very important to computer scientists. These families constitute the
More information1. Nondeterministically guess a solution (called a certificate) 2. Check whether the solution solves the problem (called verification)
Some N P problems Computer scientists have studied many N P problems, that is, problems that can be solved nondeterministically in polynomial time. Traditionally complexity question are studied as languages:
More informationPage 1. CSCE 310J Data Structures & Algorithms. CSCE 310J Data Structures & Algorithms. P, NP, and NP-Complete. Polynomial-Time Algorithms
CSCE 310J Data Structures & Algorithms P, NP, and NP-Complete Dr. Steve Goddard goddard@cse.unl.edu CSCE 310J Data Structures & Algorithms Giving credit where credit is due:» Most of the lecture notes
More informationCSE 135: Introduction to Theory of Computation Decidability and Recognizability
CSE 135: Introduction to Theory of Computation Decidability and Recognizability Sungjin Im University of California, Merced 04-28, 30-2014 High-Level Descriptions of Computation Instead of giving a Turing
More informationWelcome to... Problem Analysis and Complexity Theory 716.054, 3 VU
Welcome to... Problem Analysis and Complexity Theory 716.054, 3 VU Birgit Vogtenhuber Institute for Software Technology email: bvogt@ist.tugraz.at office hour: Tuesday 10:30 11:30 slides: http://www.ist.tugraz.at/pact.html
More informationTuring Machines: An Introduction
CIT 596 Theory of Computation 1 We have seen several abstract models of computing devices: Deterministic Finite Automata, Nondeterministic Finite Automata, Nondeterministic Finite Automata with ɛ-transitions,
More informationOHJ-2306 Introduction to Theoretical Computer Science, Fall 2012 8.11.2012
276 The P vs. NP problem is a major unsolved problem in computer science It is one of the seven Millennium Prize Problems selected by the Clay Mathematics Institute to carry a $ 1,000,000 prize for the
More informationComplexity Theory. IE 661: Scheduling Theory Fall 2003 Satyaki Ghosh Dastidar
Complexity Theory IE 661: Scheduling Theory Fall 2003 Satyaki Ghosh Dastidar Outline Goals Computation of Problems Concepts and Definitions Complexity Classes and Problems Polynomial Time Reductions Examples
More informationThe Halting Problem is Undecidable
185 Corollary G = { M, w w L(M) } is not Turing-recognizable. Proof. = ERR, where ERR is the easy to decide language: ERR = { x { 0, 1 }* x does not have a prefix that is a valid code for a Turing machine
More informationQuantum and Non-deterministic computers facing NP-completeness
Quantum and Non-deterministic computers facing NP-completeness Thibaut University of Vienna Dept. of Business Administration Austria Vienna January 29th, 2013 Some pictures come from Wikipedia Introduction
More informationNP-Completeness and Cook s Theorem
NP-Completeness and Cook s Theorem Lecture notes for COM3412 Logic and Computation 15th January 2002 1 NP decision problems The decision problem D L for a formal language L Σ is the computational task:
More informationIntroduction to NP-Completeness Written and copyright c by Jie Wang 1
91.502 Foundations of Comuter Science 1 Introduction to Written and coyright c by Jie Wang 1 We use time-bounded (deterministic and nondeterministic) Turing machines to study comutational comlexity of
More informationAlgebraic Computation Models. Algebraic Computation Models
Algebraic Computation Models Ζυγομήτρος Ευάγγελος ΜΠΛΑ 201118 Φεβρουάριος, 2013 Reasons for using algebraic models of computation The Turing machine model captures computations on bits. Many algorithms
More informationLecture 7: NP-Complete Problems
IAS/PCMI Summer Session 2000 Clay Mathematics Undergraduate Program Basic Course on Computational Complexity Lecture 7: NP-Complete Problems David Mix Barrington and Alexis Maciel July 25, 2000 1. Circuit
More informationComputability Theory
CSC 438F/2404F Notes (S. Cook and T. Pitassi) Fall, 2014 Computability Theory This section is partly inspired by the material in A Course in Mathematical Logic by Bell and Machover, Chap 6, sections 1-10.
More informationLecture 1: Oracle Turing Machines
Computational Complexity Theory, Fall 2008 September 10 Lecture 1: Oracle Turing Machines Lecturer: Kristoffer Arnsfelt Hansen Scribe: Casper Kejlberg-Rasmussen Oracle TM Definition 1 Let A Σ. Then a Oracle
More informationIntroduction to Logic in Computer Science: Autumn 2006
Introduction to Logic in Computer Science: Autumn 2006 Ulle Endriss Institute for Logic, Language and Computation University of Amsterdam Ulle Endriss 1 Plan for Today Now that we have a basic understanding
More informationCS 3719 (Theory of Computation and Algorithms) Lecture 4
CS 3719 (Theory of Computation and Algorithms) Lecture 4 Antonina Kolokolova January 18, 2012 1 Undecidable languages 1.1 Church-Turing thesis Let s recap how it all started. In 1990, Hilbert stated a
More information24 Uses of Turing Machines
Formal Language and Automata Theory: CS2004 24 Uses of Turing Machines 24 Introduction We have previously covered the application of Turing Machine as a recognizer and decider In this lecture we will discuss
More informationIntroduction to Algorithms. Part 3: P, NP Hard Problems
Introduction to Algorithms Part 3: P, NP Hard Problems 1) Polynomial Time: P and NP 2) NP-Completeness 3) Dealing with Hard Problems 4) Lower Bounds 5) Books c Wayne Goddard, Clemson University, 2004 Chapter
More informationComputational Models Lecture 8, Spring 2009
Slides modified by Benny Chor, based on original slides by Maurice Herlihy, Brown Univ. p. 1 Computational Models Lecture 8, Spring 2009 Encoding of TMs Universal Turing Machines The Halting/Acceptance
More informationSIMS 255 Foundations of Software Design. Complexity and NP-completeness
SIMS 255 Foundations of Software Design Complexity and NP-completeness Matt Welsh November 29, 2001 mdw@cs.berkeley.edu 1 Outline Complexity of algorithms Space and time complexity ``Big O'' notation Complexity
More informationNotes on Complexity Theory Last updated: August, 2011. Lecture 1
Notes on Complexity Theory Last updated: August, 2011 Jonathan Katz Lecture 1 1 Turing Machines I assume that most students have encountered Turing machines before. (Students who have not may want to look
More informationComplexity Classes. Chapter 27 of the forthcoming CRC Handbook on Algorithms and Theory of Computation. Eric Allender 1. Rutgers University
Complexity Classes Chapter 27 of the forthcoming CRC Handbook on Algorithms and Theory of Computation Eric Allender 1 Rutgers University Michael C. Loui 2 University of Illinois at Urbana-Champaign 1 Introduction
More informationUniversality in the theory of algorithms and computer science
Universality in the theory of algorithms and computer science Alexander Shen Computational models The notion of computable function was introduced in 1930ies. Simplifying (a rather interesting and puzzling)
More informationComplexity Classes P and NP
Complexity Classes P and NP MATH 3220 Supplemental Presentation by John Aleshunas The cure for boredom is curiosity. There is no cure for curiosity Dorothy Parker Computational Complexity Theory In computer
More informationTutorial 8. NP-Complete Problems
Tutorial 8 NP-Complete Problems Decision Problem Statement of a decision problem Part 1: instance description defining the input Part 2: question stating the actual yesor-no question A decision problem
More informationCAs and Turing Machines. The Basis for Universal Computation
CAs and Turing Machines The Basis for Universal Computation What We Mean By Universal When we claim universal computation we mean that the CA is capable of calculating anything that could possibly be calculated*.
More informationNP-complete? NP-hard? Some Foundations of Complexity. Prof. Sven Hartmann Clausthal University of Technology Department of Informatics
NP-complete? NP-hard? Some Foundations of Complexity Prof. Sven Hartmann Clausthal University of Technology Department of Informatics Tractability of Problems Some problems are undecidable: no computer
More information1 Definition of a Turing machine
Introduction to Algorithms Notes on Turing Machines CS 4820, Spring 2012 April 2-16, 2012 1 Definition of a Turing machine Turing machines are an abstract model of computation. They provide a precise,
More informationTuring Machines, Part I
Turing Machines, Part I Languages The $64,000 Question What is a language? What is a class of languages? Computer Science Theory 2 1 Now our picture looks like Context Free Languages Deterministic Context
More informationTHE TURING DEGREES AND THEIR LACK OF LINEAR ORDER
THE TURING DEGREES AND THEIR LACK OF LINEAR ORDER JASPER DEANTONIO Abstract. This paper is a study of the Turing Degrees, which are levels of incomputability naturally arising from sets of natural numbers.
More informationComplexity Theory. Jörg Kreiker. Summer term 2010. Chair for Theoretical Computer Science Prof. Esparza TU München
Complexity Theory Jörg Kreiker Chair for Theoretical Computer Science Prof. Esparza TU München Summer term 2010 Lecture 8 PSPACE 3 Intro Agenda Wrap-up Ladner proof and time vs. space succinctness QBF
More information6.080/6.089 GITCS Feb 12, 2008. Lecture 3
6.8/6.89 GITCS Feb 2, 28 Lecturer: Scott Aaronson Lecture 3 Scribe: Adam Rogal Administrivia. Scribe notes The purpose of scribe notes is to transcribe our lectures. Although I have formal notes of my
More informationComplexity Classes. Eric Allender Rutgers University. Michael C. Loui University of Illinois at Urbana-Champaign
Complexity Classes Eric Allender Rutgers University Michael C. Loui University of Illinois at Urbana-Champaign Kenneth W. Regan State University of New York at Buffalo 1 Introduction The purposes of complexity
More informationChapter. NP-Completeness. Contents
Chapter 13 NP-Completeness Contents 13.1 P and NP......................... 593 13.1.1 Defining the Complexity Classes P and NP...594 13.1.2 Some Interesting Problems in NP.......... 597 13.2 NP-Completeness....................
More informationTuring Machines and Understanding Computational Complexity
Turing Machines and Understanding Computational Complexity Paul M.B.Vitányi CWI, Science Park 123, 1098XG Amsterdam The Netherlands 1. Introduction A Turing machine refers to a hypothetical machine proposed
More informationAutomata and Computability. Solutions to Exercises
Automata and Computability Solutions to Exercises Fall 25 Alexis Maciel Department of Computer Science Clarkson University Copyright c 25 Alexis Maciel ii Contents Preface vii Introduction 2 Finite Automata
More informationLecture summary for Theory of Computation
Lecture summary for Theory of Computation Sandeep Sen 1 January 8, 2015 1 Department of Computer Science and Engineering, IIT Delhi, New Delhi 110016, India. E- mail:ssen@cse.iitd.ernet.in Contents 1 The
More informationA Working Knowledge of Computational Complexity for an Optimizer
A Working Knowledge of Computational Complexity for an Optimizer ORF 363/COS 323 Instructor: Amir Ali Ahmadi TAs: Y. Chen, G. Hall, J. Ye Fall 2014 1 Why computational complexity? What is computational
More informationMATHEMATICS: CONCEPTS, AND FOUNDATIONS Vol. III - Logic and Computer Science - Phokion G. Kolaitis
LOGIC AND COMPUTER SCIENCE Phokion G. Kolaitis Computer Science Department, University of California, Santa Cruz, CA 95064, USA Keywords: algorithm, Armstrong s axioms, complete problem, complexity class,
More informationPushdown Automata. place the input head on the leftmost input symbol. while symbol read = b and pile contains discs advance head remove disc from pile
Pushdown Automata In the last section we found that restricting the computational power of computing devices produced solvable decision problems for the class of sets accepted by finite automata. But along
More informationNotes on NP Completeness
Notes on NP Completeness Rich Schwartz November 10, 2013 1 Overview Here are some notes which I wrote to try to understand what NP completeness means. Most of these notes are taken from Appendix B in Douglas
More informationProperties of Stabilizing Computations
Theory and Applications of Mathematics & Computer Science 5 (1) (2015) 71 93 Properties of Stabilizing Computations Mark Burgin a a University of California, Los Angeles 405 Hilgard Ave. Los Angeles, CA
More informationComputational complexity theory
Computational complexity theory Goal: A general theory of the resources needed to solve computational problems What types of resources? Time What types of computational problems? decision problem Decision
More information(67902) Topics in Theory and Complexity Nov 2, 2006. Lecture 7
(67902) Topics in Theory and Complexity Nov 2, 2006 Lecturer: Irit Dinur Lecture 7 Scribe: Rani Lekach 1 Lecture overview This Lecture consists of two parts In the first part we will refresh the definition
More informationP versus NP, and More
1 P versus NP, and More Great Ideas in Theoretical Computer Science Saarland University, Summer 2014 If you have tried to solve a crossword puzzle, you know that it is much harder to solve it than to verify
More informationTHE SEARCH FOR NATURAL DEFINABILITY IN THE TURING DEGREES
THE SEARCH FOR NATURAL DEFINABILITY IN THE TURING DEGREES ANDREW E.M. LEWIS 1. Introduction This will be a course on the Turing degrees. We shall assume very little background knowledge: familiarity with
More informationGeneralized CHR machines
K.U.Leuven, Belgium Universität Ulm, Germany CHR 08 Workshop Hagenberg, Austria, July 2008 Complexity-wise completeness CHR machines 2/27 1 Introduction Complexity-wise completeness CHR machines 2 3 4
More informationNondeterministic polynomial time factoring in the tile assembly model
Theoretical Computer Science 395 2008) 3 23 www.elsevier.com/locate/tcs Nondeterministic polynomial time factoring in the tile assembly model Yuriy Brun Department of Computer Science, University of Southern
More informationOn the Relationship between Classes P and NP
Journal of Computer Science 8 (7): 1036-1040, 2012 ISSN 1549-3636 2012 Science Publications On the Relationship between Classes P and NP Anatoly D. Plotnikov Department of Computer Systems and Networks,
More informationSimulation-Based Security with Inexhaustible Interactive Turing Machines
Simulation-Based Security with Inexhaustible Interactive Turing Machines Ralf Küsters Institut für Informatik Christian-Albrechts-Universität zu Kiel 24098 Kiel, Germany kuesters@ti.informatik.uni-kiel.de
More informationCSC 373: Algorithm Design and Analysis Lecture 16
CSC 373: Algorithm Design and Analysis Lecture 16 Allan Borodin February 25, 2013 Some materials are from Stephen Cook s IIT talk and Keven Wayne s slides. 1 / 17 Announcements and Outline Announcements
More informationWhy? A central concept in Computer Science. Algorithms are ubiquitous.
Analysis of Algorithms: A Brief Introduction Why? A central concept in Computer Science. Algorithms are ubiquitous. Using the Internet (sending email, transferring files, use of search engines, online
More informationChapter 7 Uncomputability
Chapter 7 Uncomputability 190 7.1 Introduction Undecidability of concrete problems. First undecidable problem obtained by diagonalisation. Other undecidable problems obtained by means of the reduction
More information(IALC, Chapters 8 and 9) Introduction to Turing s life, Turing machines, universal machines, unsolvable problems.
3130CIT: Theory of Computation Turing machines and undecidability (IALC, Chapters 8 and 9) Introduction to Turing s life, Turing machines, universal machines, unsolvable problems. An undecidable problem
More information6.045: Automata, Computability, and Complexity Or, Great Ideas in Theoretical Computer Science Spring, 2010. Class 4 Nancy Lynch
6.045: Automata, Computability, and Complexity Or, Great Ideas in Theoretical Computer Science Spring, 2010 Class 4 Nancy Lynch Today Two more models of computation: Nondeterministic Finite Automata (NFAs)
More informationFormal Languages and Automata Theory - Regular Expressions and Finite Automata -
Formal Languages and Automata Theory - Regular Expressions and Finite Automata - Samarjit Chakraborty Computer Engineering and Networks Laboratory Swiss Federal Institute of Technology (ETH) Zürich March
More informationRegular Expressions and Automata using Haskell
Regular Expressions and Automata using Haskell Simon Thompson Computing Laboratory University of Kent at Canterbury January 2000 Contents 1 Introduction 2 2 Regular Expressions 2 3 Matching regular expressions
More informationTwo-dimensional Languages
Charles University Faculty of Mathematics and Physics Mgr. Daniel Průša Two-dimensional Languages Doctoral Thesis Supervisor: Martin Plátek, CSc. Prague, 2004 Acknowledgements The results presented in
More informationFixed-Point Logics and Computation
1 Fixed-Point Logics and Computation Symposium on the Unusual Effectiveness of Logic in Computer Science University of Cambridge 2 Mathematical Logic Mathematical logic seeks to formalise the process of
More informationReminder: Complexity (1) Parallel Complexity Theory. Reminder: Complexity (2) Complexity-new
Reminder: Complexity (1) Parallel Complexity Theory Lecture 6 Number of steps or memory units required to compute some result In terms of input size Using a single processor O(1) says that regardless of
More informationReminder: Complexity (1) Parallel Complexity Theory. Reminder: Complexity (2) Complexity-new GAP (2) Graph Accessibility Problem (GAP) (1)
Reminder: Complexity (1) Parallel Complexity Theory Lecture 6 Number of steps or memory units required to compute some result In terms of input size Using a single processor O(1) says that regardless of
More informationThe P versus NP Solution
The P versus NP Solution Frank Vega To cite this version: Frank Vega. The P versus NP Solution. 2015. HAL Id: hal-01143424 https://hal.archives-ouvertes.fr/hal-01143424 Submitted on 17 Apr
More informationNP-Completeness I. Lecture 19. 19.1 Overview. 19.2 Introduction: Reduction and Expressiveness
Lecture 19 NP-Completeness I 19.1 Overview In the past few lectures we have looked at increasingly more expressive problems that we were able to solve using efficient algorithms. In this lecture we introduce
More informationOutline Introduction Circuits PRGs Uniform Derandomization Refs. Derandomization. A Basic Introduction. Antonis Antonopoulos.
Derandomization A Basic Introduction Antonis Antonopoulos CoReLab Seminar National Technical University of Athens 21/3/2011 1 Introduction History & Frame Basic Results 2 Circuits Definitions Basic Properties
More informationChapter 1. NP Completeness I. 1.1. Introduction. By Sariel Har-Peled, December 30, 2014 1 Version: 1.05
Chapter 1 NP Completeness I By Sariel Har-Peled, December 30, 2014 1 Version: 1.05 "Then you must begin a reading program immediately so that you man understand the crises of our age," Ignatius said solemnly.
More informationSOLVING NARROW-INTERVAL LINEAR EQUATION SYSTEMS IS NP-HARD PATRICK THOR KAHL. Department of Computer Science
SOLVING NARROW-INTERVAL LINEAR EQUATION SYSTEMS IS NP-HARD PATRICK THOR KAHL Department of Computer Science APPROVED: Vladik Kreinovich, Chair, Ph.D. Luc Longpré, Ph.D. Mohamed Amine Khamsi, Ph.D. Pablo
More informationHow To Compare A Markov Algorithm To A Turing Machine
Markov Algorithm CHEN Yuanmi December 18, 2007 1 Abstract Markov Algorithm can be understood as a priority string rewriting system. In this short paper we give the definition of Markov algorithm and also
More informationProof Systems that Take Advice
Proof Systems that Take Advice Olaf Beyersdorff 1, Johannes Köbler 2, and Sebastian Müller 2 1 Institut für Theoretische Informatik, Leibniz-Universität Hannover, Germany beyersdorff@thi.uni-hannover.de
More informationA logical approach to dynamic role-based access control
A logical approach to dynamic role-based access control Philippe Balbiani Yannick Chevalier Marwa El Houri Abstract Since its formalization RBAC has become the yardstick for the evaluation of access control
More informationFinite Automata. Reading: Chapter 2
Finite Automata Reading: Chapter 2 1 Finite Automaton (FA) Informally, a state diagram that comprehensively captures all possible states and transitions that a machine can take while responding to a stream
More informationSecrecy for Bounded Security Protocols With Freshness Check is NEXPTIME-complete
Journal of Computer Security vol 16, no 6, 689-712, 2008. Secrecy for Bounded Security Protocols With Freshness Check is NEXPTIME-complete Ferucio L. Țiplea a), b), Cătălin V. Bîrjoveanu a), Constantin
More informationIntroduction to computer science
Introduction to computer science Michael A. Nielsen University of Queensland Goals: 1. Introduce the notion of the computational complexity of a problem, and define the major computational complexity classes.
More informationLecture 2: Complexity Theory Review and Interactive Proofs
600.641 Special Topics in Theoretical Cryptography January 23, 2007 Lecture 2: Complexity Theory Review and Interactive Proofs Instructor: Susan Hohenberger Scribe: Karyn Benson 1 Introduction to Cryptography
More informationGuessing Game: NP-Complete?
Guessing Game: NP-Complete? 1. LONGEST-PATH: Given a graph G = (V, E), does there exists a simple path of length at least k edges? YES 2. SHORTEST-PATH: Given a graph G = (V, E), does there exists a simple
More informationImplementation of Recursively Enumerable Languages using Universal Turing Machine in JFLAP
International Journal of Information and Computation Technology. ISSN 0974-2239 Volume 4, Number 1 (2014), pp. 79-84 International Research Publications House http://www. irphouse.com /ijict.htm Implementation
More informationPushdown automata. Informatics 2A: Lecture 9. Alex Simpson. 3 October, 2014. School of Informatics University of Edinburgh als@inf.ed.ac.
Pushdown automata Informatics 2A: Lecture 9 Alex Simpson School of Informatics University of Edinburgh als@inf.ed.ac.uk 3 October, 2014 1 / 17 Recap of lecture 8 Context-free languages are defined by context-free
More information2.1 Complexity Classes
15-859(M): Randomized Algorithms Lecturer: Shuchi Chawla Topic: Complexity classes, Identity checking Date: September 15, 2004 Scribe: Andrew Gilpin 2.1 Complexity Classes In this lecture we will look
More informationQuantum Computability and Complexity and the Limits of Quantum Computation
Quantum Computability and Complexity and the Limits of Quantum Computation Eric Benjamin, Kenny Huang, Amir Kamil, Jimmy Kittiyachavalit University of California, Berkeley December 7, 2003 This paper will
More informationOn the Unique Games Conjecture
On the Unique Games Conjecture Antonios Angelakis National Technical University of Athens June 16, 2015 Antonios Angelakis (NTUA) Theory of Computation June 16, 2015 1 / 20 Overview 1 Introduction 2 Preliminary
More informationIntroduction to Automata Theory. Reading: Chapter 1
Introduction to Automata Theory Reading: Chapter 1 1 What is Automata Theory? Study of abstract computing devices, or machines Automaton = an abstract computing device Note: A device need not even be a
More informationRevisiting a Limit on Efficient Quantum Computation
Revisiting a Limit on Efficient Quantum Computation Tarsem S. Purewal Jr. Department of Computer Science University of Georgia Athens, GA 30602 purewal@cs.uga.edu ABSTRACT In this paper, we offer an exposition
More informationIntroduction to Turing Machines
Automata Theory, Languages and Computation - Mírian Halfeld-Ferrari p. 1/2 Introduction to Turing Machines SITE : http://www.sir.blois.univ-tours.fr/ mirian/ Automata Theory, Languages and Computation
More informationHypercomputation: computing more than the Turing machine
Hypercomputation: computing more than the Turing machine Abstract: Toby Ord Department of Philosophy * The University of Melbourne t.ord@pgrad.unimelb.edu.au In this report I provide an introduction to
More information6.080 / 6.089 Great Ideas in Theoretical Computer Science Spring 2008
MIT OpenCourseWare http://ocw.mit.edu 6.080 / 6.089 Great Ideas in Theoretical Computer Science Spring 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.
More informationThe Parameterized Complexity of Short Computation and Factorization
The Parameterized Complexity of Short Computation and Factorization Liming Cai and Jianer Chen Department of Computer Science, Texas A & M University College Station, Texas 77843 U.S.A. Rodney G. Downey
More informationCS 301 Course Information
CS 301: Languages and Automata January 9, 2009 CS 301 Course Information Prof. Robert H. Sloan Handout 1 Lecture: Tuesday Thursday, 2:00 3:15, LC A5 Weekly Problem Session: Wednesday, 4:00 4:50 p.m., LC
More information6.852: Distributed Algorithms Fall, 2009. Class 2
.8: Distributed Algorithms Fall, 009 Class Today s plan Leader election in a synchronous ring: Lower bound for comparison-based algorithms. Basic computation in general synchronous networks: Leader election
More informationT-79.186 Reactive Systems: Introduction and Finite State Automata
T-79.186 Reactive Systems: Introduction and Finite State Automata Timo Latvala 14.1.2004 Reactive Systems: Introduction and Finite State Automata 1-1 Reactive Systems Reactive systems are a class of software
More information! X is a set of strings. ! Instance: string s. ! Algorithm A solves problem X: A(s) = yes iff s! X.
Decision Problems 8.2 Definition of NP Decision problem. X is a set of strings. Instance: string s. Algorithm A solves problem X: A(s) = yes iff s X. Polynomial time. Algorithm A runs in polytime if for
More informationQuantum Monte Carlo and the negative sign problem
Quantum Monte Carlo and the negative sign problem or how to earn one million dollar Matthias Troyer, ETH Zürich Uwe-Jens Wiese, Universität Bern Complexity of many particle problems Classical 1 particle:
More information898 BOOK REVIEWS MICHAEL P. DRAZIN. irrespective of the statements in The New York Times, November 7, 1979, p. 1.
898 BOOK REVIEWS linear algebra texts; it would have been well worth taking space to develop this theme at some length. To summarize, after its renaissance in the 1950s, GI theory passed through its infancy
More information