Table Of Content

=ý. !I . 1(cid:127). |~ilH Terms Meaning Section Sets, Proof Templates, and Induction x e A x is an element ofA 1.1 x f A x is not an element ofA 1.1 Ix x E A and P(x)} Set notation 1.1 N Natural numbers 1.1.1l 2 Integers 1.1.1 Q Rationals 1.1.1 R Real numbers I.1.1 A = B Sets A and B are equal 1.1.3 A C B A is a subset of B 1.1.5 A g B A is nota subset of B 1.1.5 A C B A is a proper subset of B 1.1.5 A 5 B A is nota proper subset of B 1.1.5 b=(cid:127)a bimplies a i.1.5 a b a if and only if b 1.1.5 AUB A union B 1.3.1 AFnB A intersect B 1.3.1 UX Generalized union of family of sets X 1.3.1 nX Generalized intersection of family of sets X 1.3.1 Um Xi Xm U ... UXn 1.3.1 nt=Mxi Xm n ... n Xn 1.3.1 A - B Elements of A not in B 1.3.2 A Elements not in A 1.3.2 A D B (A U B) - (A n B) 1.3.2 P(X) Power set of X 1.3.4 X x Y Product of X and Y 1.3.4 x A y Meet ofx and y 1.3.5 x v y Join ofx and y 1.3.5 -x Complement of x 1.3.5 T Top 1.15 I Bottom 1.3.5 JAI Cardinality of A 1.5.1 Si a,, + " -".+ a,, 1.7.1 Terms Meaning Section Formal Logic "--p Not p 2.1 pAq p and q 2.1 pvq p or q 2.1 p q p implies q 2.1 p q p is equivalent to q 2.1 S X S logically implies X 2.3.3 P 3 AKP Conjecture about complexity 2.5.6 (Vx)P(x) For all x, P(x) 2.7.2 (3x)P(x) There exists an x such that P(x) 2.7.2 (VxE V)P(x) For all X EV, P(x) 2.7.3 (3x E V)P(x) There exists an x E V such that P(x) 2.7.3 A[i . .j] Array with elements Ail, ... , A[j] 2.7.3 1 Sheffer stroke 2.4 V Exclusive or 2.4 4, Pierce arrow 2.9 (x, y) E R or xRy x is R-related to y 3.1 R-1 The inverse of the relation R 3.2.1 RoS Composition of relations R and S 3.2.2 R+ U°° Ri 3.4.4 R* URO R' 3.4.4 n =-m (modp) n - m = kp for some k E N 3.6 Idx Identity relation 3.1 Lex Less than or equal relation 3.1 Gtx Greater than relation 3.1 Gex Greater than or equal relation 3.1 [x] Equivalence class of x 3.6 min m divides n 3.8.1 R D. S Equijoin of relations R and S 3.10.2 www.brookscole.com www.brookscole.com is the World Wide Web site for Brooks/Cole and is your direct source to dozens of online resources. At www.brookscole.com you can find out about supplements, demonstration software, and student resources. You can also send email to many of our authors and preview new publications and exciting new technologies. www.brookscole.com Changing the way the world learns Discrete Mathematics for Computer Science fo Copue Science Gary Haggard Bucknell University John Schlipf University of Cincinnati Sue Whitesides McGill University THOrVIMSO3N BROOGKS/COLE Australia Canada Mexico • Singapore • Spain United Kingdom • United States THOIMSO>N BROOKS/COLE Publisher: Bob Pirtle Production Service: Hearthside PublishingS ervice; Assistant Editor: Stacy Green Anne Seitz Editorial Assistant: Katherine Cook Text Designer: Roy Neuhaus Technology Project Manager: Earl Perry Copy Editor: HearthsideP ublishing Service; Marketing Manager: Tom Ziolkowski Wesley Morrison Marketing Assistant: Erin Mitchell Illustrator: Hearthside PublishingS ervice; Advertising Project Manager: Bryan Vann Jade Myers Signing Representative: Stephanie Shedlock Cover Designer: Roy R. 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Mexico Spain/Portugal 4 EcyO'- Paraninfo Calle Magallanes, 25 28015 Madrid Spain Contents CHAPTER 1 Sets, Proof Templates, and Induction 1.1 Basic Definitions 1 1.1.1 Describing Sets Mathematically 2 1.1.2 Set Membership 4 1.1.3 Equality of Sets 4 1.1.4 Finite and Infinite Sets 5 1.1.5 Relations Between Sets 5 1.1.6 Venn Diagrams 7 1.1.7 Templates 8 1.2 Exercises 13 1.3 Operations on Sets 15 1.3.1 Union and Intersection 15 1.3.2 Set Difference, Complements, and DeMorgan's Laws 20 1.3.3 New Proof Templates 26 1.3.4 Power Sets and Products 28 1.3.5 Lattices and Boolean Algebras 28 1.4 Exercises 31 1.5 The Principle of Inclusion-Exclusion 34 1.5.1 Finite Cardinality 34 1.5.2 Principle of Inclusion-Exclusion for Two Sets 36 1.5.3 Principle of Inclusion-Exclusion for Three Sets 37 1.5.4 Principle of Inclusion-Exclusion for Finitely Many Sets 41 1.6 Exercises 42 vii viii Contents 1.7 Mathematical Induction 45 1.71 A First Form of Induction 45 1.72 A Template for Constructing Proofs by Induction 49 1.73 Application: Fibonacci Numbers 51 1.74 Application: Size of a Power Set 53 1.75 Application: Geometric Series 54 1.8 Program Correctness 56 1.8.1 Pseudocode Conventions 56 1.8.2 An Algorithm to Generate Perfect Squares 58 1.8.3 Two Algorithms for Computing Square Roots 58 1.9 Exercises 62 1.10 Strong Form of Mathematical Induction 66 1.10.1 Using the Strong Form of Mathematical Induction 69 1.10.2 Application: Algorithm to Compute Powers 72 1.10.3 Application: Finding Factorizations 75 1.10.4 Application: Binary Search 77 1.11 Exercises 79 1.12 Chapter Review 81 1.12.1 Summary 82 1.12.2 Starting to Review 84 1.12.3 Review Questions 85 1.12.4 Using Discrete Mathematics in Computer Science 87 2 CHAPTER Formal Logic 89 2.1 Introduction to Propositional Logic 89 2.1.1 Formulas 92 2.1.2 Expression Trees for Formulas 94 2.1.3 Abbreviated Notation for Formulas 97 2.1.4 Using Gates to Represent Formulas 98 2.2 Exercises 99 2.3 Truth and Logical Truth 102 2.3.1 Tautologies 106 Contents ix 2.3.2 Substitutions into Tautologies 109 2.3.3 Logically Valid Inferences 109 2.3.4 Combinatorial Networks 112 2.3.5 Substituting Equivalent Subformulas 114 2.3.6 Simplifying Negations 115 2.4 Exercises 116 2.5 Normal Forms 121 2.5.1 Disjunctive Normal Form 122 2.5.2 Application: DNF and Combinatorial Networks 124 2.5.3 Conjunctive Normal Form 125 2.5.4 Application: CNF and Combinatorial Networks 127 2.5.5 Testing Satisfiability and Validity 127 2.5.6 The Famous 'P Afr Conjecture 129 2.5.7 Resolution Proofs: Automating Logic 129 2.6 Exercises 131 2.7 Predicates and Quantification 134 2.71 Predicates 135 2.72 Quantification 135 2.73 Restricted Quantification 136 2.74 Nested Quantifiers 137 2.75 Negation and Quantification 138 2.76 Quantification with Conjunction and Disjunction 139 2.77 Application: Loop Invariant Assertions 141 2.8 Exercises 143 2.9 Chapter Review 147 2.9.1 Summary 148 2.9.2 Starting to Review 149 2.9.3 Review Questions 150 2.9.4 Using Discrete Mathematics in Computer Science 151 3 CHAPTER Relations 157 3.1 Binary Relations 157 3.1.1 n-ary Relations 162