Harvard University, Math 101, Spring 2015

Size: px
Start display at page:

Download "Harvard University, Math 101, Spring 2015"

Transcription

1 Harvard University, Math 101, Spring 2015 Lecture 1 and 2 : Introduction to propositional logic 1 Logical statements A statement is a sentence that is either true or false, but not both. Some examples: 1. 1 is smaller than is an odd number 3. 2 is a rational number 4. x N (1) and (2) are true statements while (3) is a false statement and (4) is not a statement since its validity depends on an unspecified variable x. 2 Logical operators A logical operator or a Boolean operator is a function that takes as entries one or several statements and returns another statement. In propositional logic, we use propositional variables that we will denote by roman letters such as a, b, p, q, and s. A formula consists of propositional variables connected by logical operators. A valuation is a function that attached to each propositional variable either 1 for truth or 0 for falsity. We can define a logical operator by the values it takes for all possible valuations of its entries. Such valuations are organized in a truth table. Two logical operators are equivalent when they have the same truth table. 2.1 The negation: the NOT operator The negation (the NOT operator) is a unary operator 1 that takes a statement and returns its negation. We denote the negation of a statement p by p or p. Given a statement p, p is true if p is false, and p is false if p is true. This is summarized in the following truth table: p p The conjunction : the AND operator The AND operator is a binary operator 2 that is true if and only if both of its entries are true. It is defined by the following table: 1 A unary operator is an operator with only one entry. 2 A binary operator is an operator with two entries. p q p q

2 2.3 The (inclusive) disjunction: the OR operator The OR operator is a binary operator that is true if and only if at least one of its entries is true. It is false if and only if both of its entries are false. It is defined by the following table: p q p q By comparing tables, we can prove that the OR operator can be expressed in terms of the AND and NOT operator. More precisely, we have the p q p q. To prove this theorem, we need to show that p q has the same truth table as p q. This is indeed the case. To compute the truth table of p q, we starts by enumerating all the possible valuations for p and q, we can then compute those of p and q and finally compute those of p q: p q p q p q We can also prove the following dual statement: Proof. : p q p q. p q p q p q p q The last two columns are the same, which shows that p q p q The implication: the If...Then... operator The If...Then... operator is a binary operator that is false if and only if the first entry is true while the second entry is false. It is defined by the following table: p q p = q

3 We can show that (p = q) p q. Proof. p q p q p = q p q The last two columns are the same, which establishes the equivalence. The statement p = q is also called a conditional statement. From that point of vue p is called the hypothesis and q is the conclusion or implication. Given the conditional statement p = q, q = p is called the converse of p = q p = q is called the inverse of p = q q = p is called its contrapositive of p = q We will see that a conditional statement is equivalent to its contrapositive while its converse is equivalent to its inverse. However, the conditional statement is usually not equivalent to its converse. 2.5 Equivalence : the If and Only If operator The equivalence operator is a binary operator that is false if the two entries have different truth values. It is defined by the following truth table: p q p q We can show that (p q) (p = q) (q = p). or equivalently (p q) (p q) (q p). The equivalence symbol is actually not necessary since it is exactly the same as the operator. 2.6 The Exclusive disjunction: the XOR operator The exclusive disjunction is true if and only if the two entries have different valuation: p q p + q

4 We can show that it is the negation of the equivalence operator: p + q p q. 3 Basic properties of logical operators Summary of the truth tables Negation of logical operators: p q p q p q p = q p q p + q p p p q p q p q p q p = q p q p q (p q) p + q Indempotence Simplifications Distributivity: Associativity: p p p p p p p 1 p p 0 p (1 = p) p (p = 0) p a (b c) (a b) (a c) a (b c) (a b) (a c) Commutativity a (b c) (a b) c a (b c) (a b) c p q q p p q q p p + q q + p p q q p The following theorems are also very handy to replace implications by a combination of NOT, OR, and AND operators: (p = q) p q (p q) (p = q) (q = p) (p q) (p q) 4

5 4 Tautologies A tautology is a formula that is always true. A contradiction is the negation of a tautology. A simple way to construct a tautology is to start from an equivalence a b and to replace the symbol by the operator. We now review a list of famous tautologies: The law of double negation: p p This is just the statement that the negation is an involutive operator (it squares to the identity). The law of excluded middle: p p The law of excluded middle reflects the fact that a propositional variables always have a well defined truth values, it is either true or false. The law of contraposition: (p = q) (q = p) The law of contraposition is often used in mathematical proof: to prove that p implies q it is sometimes easier to prove that q implies p. Dualities or de Morgan s laws: Syllogism: p q p q p q p q (a = b) (b = c) = (a = c) The syllogism is essentially the statement that the implication operator = is transitive. Proof by cases: (a b) (a = c) (b = c) = c If one of a or b is true and each implies c, then c is necessary true. Reductio ad absurdum: (p = q) (p = q) = p. This is a common procedure in mathematical proofs. To show that p is true, we can show that its negation implies both a proposition q and its negation q. Since q and q cannot be true at the same time, it follows that p has to be false, and therefore p is true. Modus ponens If q is true and p implies q, then q is true. p (p = q) = q 5

6 5 Boolean algebra We introduce the set Z 2 of integers modulo 2. As a set it is composed of only two elements: Z 2 = {0, 1}. The element 0 represents all the even integers and 1 to all the odd integers. Addition and multiplications are defined by the following tables: In particular = 2 but since we are in Z 2 and 2 is even, we have 2 = 0 and therefore = 0. Since the addition and multiplication are operations that take entries in Z 2 and return an element of Z 2, we can think of them as logical operators. We can write them as truth table and notice that they correspond respectively to XOR and AND: p q p + q p q p q When working with Z 2, it is useful to remember the identities: a 2 a, 2a 0. The dictionary between logical and arithmetic operators is simply: a b : a b a : 1 + a a XOR b : a + b a b : a + b + a b a b : 1 + a + b a = b : 1 + a + a b Boolean algebra is very handy for proving theorems of binary propositional logic. For example, let see that p p is a tautology: p p p + p + p p (since a b = a + b + ab) p + (1 + p) + p(1 + p) (since p = 1 + p) p p + p 2 (by distributivity) 1 + 2p (since p 2 = p in Z 2 ) 1 (since 2p = 0 in Z 2 ). We will now prove the Modus Ponens p (p = q) = q using the arithmetic of Z 2. The first step is to translate it into an arithmetic expression in Z 2 and the second step is to prove that the expression we find is equal to 1. 6

7 Since (p = q) 1 + p + pq, and is just multiplication in Z 2, we have (p ) (p = q) = q p(1 + p + pq) = q 1 + p(1 + p + pq) + p(1 + p + pq)q 1 + p + p 2 + p 2 q + pq + p 2 q + p 2 q 1 + p + p + pq + pq + pq + pq (since p 2 = p in Z 2 ) 1 (since 2p = 0 and 4pq = 0 in Z 2 ) Since (a = b) = 1 + a + ab 7

Handout #1: Mathematical Reasoning

Handout #1: Mathematical Reasoning Math 101 Rumbos Spring 2010 1 Handout #1: Mathematical Reasoning 1 Propositional Logic A proposition is a mathematical statement that it is either true or false; that is, a statement whose certainty or

More information

DISCRETE MATHEMATICS W W L CHEN

DISCRETE MATHEMATICS W W L CHEN DISCRETE MATHEMATICS W W L CHEN c W W L Chen, 1982, 2008. This chapter originates from material used by the author at Imperial College, University of London, between 1981 and 1990. It is available free

More information

CS 441 Discrete Mathematics for CS Lecture 5. Predicate logic. CS 441 Discrete mathematics for CS. Negation of quantifiers

CS 441 Discrete Mathematics for CS Lecture 5. Predicate logic. CS 441 Discrete mathematics for CS. Negation of quantifiers CS 441 Discrete Mathematics for CS Lecture 5 Predicate logic Milos Hauskrecht milos@cs.pitt.edu 5329 Sennott Square Negation of quantifiers English statement: Nothing is perfect. Translation: x Perfect(x)

More information

2. Propositional Equivalences

2. Propositional Equivalences 2. PROPOSITIONAL EQUIVALENCES 33 2. Propositional Equivalences 2.1. Tautology/Contradiction/Contingency. Definition 2.1.1. A tautology is a proposition that is always true. Example 2.1.1. p p Definition

More information

Chapter I Logic and Proofs

Chapter I Logic and Proofs MATH 1130 1 Discrete Structures Chapter I Logic and Proofs Propositions A proposition is a statement that is either true (T) or false (F), but or both. s Propositions: 1. I am a man.. I am taller than

More information

Discrete Mathematics Lecture 1 Logic of Compound Statements. Harper Langston New York University

Discrete Mathematics Lecture 1 Logic of Compound Statements. Harper Langston New York University Discrete Mathematics Lecture 1 Logic of Compound Statements Harper Langston New York University Administration Class Web Site http://cs.nyu.edu/courses/summer05/g22.2340-001/ Mailing List Subscribe at

More information

Inference Rules and Proof Methods

Inference Rules and Proof Methods Inference Rules and Proof Methods Winter 2010 Introduction Rules of Inference and Formal Proofs Proofs in mathematics are valid arguments that establish the truth of mathematical statements. An argument

More information

Logic, Sets, and Proofs

Logic, Sets, and Proofs Logic, Sets, and Proofs David A. Cox and Catherine C. McGeoch Amherst College 1 Logic Logical Statements. A logical statement is a mathematical statement that is either true or false. Here we denote logical

More information

CHAPTER 1. Logic, Proofs Propositions

CHAPTER 1. Logic, Proofs Propositions CHAPTER 1 Logic, Proofs 1.1. Propositions A proposition is a declarative sentence that is either true or false (but not both). For instance, the following are propositions: Paris is in France (true), London

More information

Section 1. Statements and Truth Tables. Definition 1.1: A mathematical statement is a declarative sentence that is true or false, but not both.

Section 1. Statements and Truth Tables. Definition 1.1: A mathematical statement is a declarative sentence that is true or false, but not both. M3210 Supplemental Notes: Basic Logic Concepts In this course we will examine statements about mathematical concepts and relationships between these concepts (definitions, theorems). We will also consider

More information

The Foundations: Logic and Proofs. Chapter 1, Part III: Proofs

The Foundations: Logic and Proofs. Chapter 1, Part III: Proofs The Foundations: Logic and Proofs Chapter 1, Part III: Proofs Rules of Inference Section 1.6 Section Summary Valid Arguments Inference Rules for Propositional Logic Using Rules of Inference to Build Arguments

More information

Discrete Mathematics, Chapter : Propositional Logic

Discrete Mathematics, Chapter : Propositional Logic Discrete Mathematics, Chapter 1.1.-1.3: Propositional Logic Richard Mayr University of Edinburgh, UK Richard Mayr (University of Edinburgh, UK) Discrete Mathematics. Chapter 1.1-1.3 1 / 21 Outline 1 Propositions

More information

31 is a prime number is a mathematical statement (which happens to be true).

31 is a prime number is a mathematical statement (which happens to be true). Chapter 1 Mathematical Logic In its most basic form, Mathematics is the practice of assigning truth to welldefined statements. In this course, we will develop the skills to use known true statements to

More information

CSE 191, Class Note 01 Propositional Logic Computer Sci & Eng Dept SUNY Buffalo

CSE 191, Class Note 01 Propositional Logic Computer Sci & Eng Dept SUNY Buffalo Propositional Logic CSE 191, Class Note 01 Propositional Logic Computer Sci & Eng Dept SUNY Buffalo c Xin He (University at Buffalo) CSE 191 Discrete Structures 1 / 37 Discrete Mathematics What is Discrete

More information

WUCT121. Discrete Mathematics. Logic

WUCT121. Discrete Mathematics. Logic WUCT121 Discrete Mathematics Logic 1. Logic 2. Predicate Logic 3. Proofs 4. Set Theory 5. Relations and Functions WUCT121 Logic 1 Section 1. Logic 1.1. Introduction. In developing a mathematical theory,

More information

Math 3000 Section 003 Intro to Abstract Math Homework 2

Math 3000 Section 003 Intro to Abstract Math Homework 2 Math 3000 Section 003 Intro to Abstract Math Homework 2 Department of Mathematical and Statistical Sciences University of Colorado Denver, Spring 2012 Solutions (February 13, 2012) Please note that these

More information

Definition 10. A proposition is a statement either true or false, but not both.

Definition 10. A proposition is a statement either true or false, but not both. Chapter 2 Propositional Logic Contrariwise, continued Tweedledee, if it was so, it might be; and if it were so, it would be; but as it isn t, it ain t. That s logic. (Lewis Carroll, Alice s Adventures

More information

1 Proposition, Logical connectives and compound statements

1 Proposition, Logical connectives and compound statements Discrete Mathematics: Lecture 4 Introduction to Logic Instructor: Arijit Bishnu Date: July 27, 2009 1 Proposition, Logical connectives and compound statements Logic is the discipline that deals with the

More information

22C:19 Discrete Math. So. What is it? Why discrete math? Fall 2009 Hantao Zhang

22C:19 Discrete Math. So. What is it? Why discrete math? Fall 2009 Hantao Zhang 22C:19 Discrete Math Fall 2009 Hantao Zhang So. What is it? Discrete mathematics is the study of mathematical structures that are fundamentally discrete, in the sense of not supporting or requiring the

More information

n logical not (negation) n logical or (disjunction) n logical and (conjunction) n logical exclusive or n logical implication (conditional)

n logical not (negation) n logical or (disjunction) n logical and (conjunction) n logical exclusive or n logical implication (conditional) Discrete Math Review Discrete Math Review (Rosen, Chapter 1.1 1.6) TOPICS Propositional Logic Logical Operators Truth Tables Implication Logical Equivalence Inference Rules What you should know about propositional

More information

Chapter 1 LOGIC AND PROOF

Chapter 1 LOGIC AND PROOF Chapter 1 LOGIC AND PROOF To be able to understand mathematics and mathematical arguments, it is necessary to have a solid understanding of logic and the way in which known facts can be combined to prove

More information

MAT2400 Analysis I. A brief introduction to proofs, sets, and functions

MAT2400 Analysis I. A brief introduction to proofs, sets, and functions MAT2400 Analysis I A brief introduction to proofs, sets, and functions In Analysis I there is a lot of manipulations with sets and functions. It is probably also the first course where you have to take

More information

def: An axiom is a statement that is assumed to be true, or in the case of a mathematical system, is used to specify the system.

def: An axiom is a statement that is assumed to be true, or in the case of a mathematical system, is used to specify the system. Section 1.5 Methods of Proof 1.5.1 1.5 METHODS OF PROOF Some forms of argument ( valid ) never lead from correct statements to an incorrect. Some other forms of argument ( fallacies ) can lead from true

More information

Symbolic Logic on the TI-92

Symbolic Logic on the TI-92 Symbolic Logic on the TI-92 Presented by Lin McMullin The Sixth Conference on the Teaching of Mathematics June 20 & 21, 1997 Milwaukee, Wisconsin 1 Lin McMullin Mathematics Department Representative, Burnt

More information

CHAPTER 2. Logic. 1. Logic Definitions. Notation: Variables are used to represent propositions. The most common variables used are p, q, and r.

CHAPTER 2. Logic. 1. Logic Definitions. Notation: Variables are used to represent propositions. The most common variables used are p, q, and r. CHAPTER 2 Logic 1. Logic Definitions 1.1. Propositions. Definition 1.1.1. A proposition is a declarative sentence that is either true (denoted either T or 1) or false (denoted either F or 0). Notation:

More information

DISCRETE MATH: LECTURE 3

DISCRETE MATH: LECTURE 3 DISCRETE MATH: LECTURE 3 DR. DANIEL FREEMAN 1. Chapter 2.2 Conditional Statements If p and q are statement variables, the conditional of q by p is If p then q or p implies q and is denoted p q. It is false

More information

Likewise, we have contradictions: formulas that can only be false, e.g. (p p).

Likewise, we have contradictions: formulas that can only be false, e.g. (p p). CHAPTER 4. STATEMENT LOGIC 59 The rightmost column of this truth table contains instances of T and instances of F. Notice that there are no degrees of contingency. If both values are possible, the formula

More information

Propositional Logic. Definition: A proposition or statement is a sentence which is either true or false.

Propositional Logic. Definition: A proposition or statement is a sentence which is either true or false. Propositional Logic Definition: A proposition or statement is a sentence which is either true or false. Definition:If a proposition is true, then we say its truth value is true, and if a proposition is

More information

Fundamentals of Mathematics Lecture 6: Propositional Logic

Fundamentals of Mathematics Lecture 6: Propositional Logic Fundamentals of Mathematics Lecture 6: Propositional Logic Guan-Shieng Huang National Chi Nan University, Taiwan Spring, 2008 1 / 39 Connectives Propositional Connectives I 1 Negation: (not A) A A T F

More information

Geometry - Chapter 2 Review

Geometry - Chapter 2 Review Name: Class: Date: Geometry - Chapter 2 Review Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Determine if the conjecture is valid by the Law of Syllogism.

More information

Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 1

Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 1 CS 70 Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 1 Course Outline CS70 is a course on Discrete Mathematics and Probability for EECS Students. The purpose of the course

More information

CS 441 Discrete Mathematics for CS Lecture 2. Propositional logic. CS 441 Discrete mathematics for CS. Course administration

CS 441 Discrete Mathematics for CS Lecture 2. Propositional logic. CS 441 Discrete mathematics for CS. Course administration CS 441 Discrete Mathematics for CS Lecture 2 Propositional logic Milos Hauskrecht milos@cs.pitt.edu 5329 Sennott Square Course administration Homework 1 First homework assignment is out today will be posted

More information

Math 3000 Running Glossary

Math 3000 Running Glossary Math 3000 Running Glossary Last Updated on: July 15, 2014 The definition of items marked with a must be known precisely. Chapter 1: 1. A set: A collection of objects called elements. 2. The empty set (

More information

Mathematical Induction

Mathematical Induction Mathematical Induction Victor Adamchik Fall of 2005 Lecture 2 (out of three) Plan 1. Strong Induction 2. Faulty Inductions 3. Induction and the Least Element Principal Strong Induction Fibonacci Numbers

More information

CHAPTER 3. Methods of Proofs. 1. Logical Arguments and Formal Proofs

CHAPTER 3. Methods of Proofs. 1. Logical Arguments and Formal Proofs CHAPTER 3 Methods of Proofs 1. Logical Arguments and Formal Proofs 1.1. Basic Terminology. An axiom is a statement that is given to be true. A rule of inference is a logical rule that is used to deduce

More information

Chapter 1. Logic and Proof

Chapter 1. Logic and Proof Chapter 1. Logic and Proof 1.1 Remark: A little over 100 years ago, it was found that some mathematical proofs contained paradoxes, and these paradoxes could be used to prove statements that were known

More information

INTRODUCTION TO PROOFS: HOMEWORK SOLUTIONS

INTRODUCTION TO PROOFS: HOMEWORK SOLUTIONS INTRODUCTION TO PROOFS: HOMEWORK SOLUTIONS STEVEN HEILMAN Contents 1. Homework 1 1 2. Homework 2 6 3. Homework 3 10 4. Homework 4 16 5. Homework 5 19 6. Homework 6 21 7. Homework 7 25 8. Homework 8 28

More information

Objectives. 2-2 Conditional Statements

Objectives. 2-2 Conditional Statements Geometry Warm Up Determine if each statement is true or false. 1. The measure of an obtuse angle is less than 90. F 2. All perfect-square numbers are positive. 3. Every prime number is odd. F 4. Any three

More information

vertex, 369 disjoint pairwise, 395 disjoint sets, 236 disjunction, 33, 36 distributive laws

vertex, 369 disjoint pairwise, 395 disjoint sets, 236 disjunction, 33, 36 distributive laws Index absolute value, 135 141 additive identity, 254 additive inverse, 254 aleph, 466 algebra of sets, 245, 278 antisymmetric relation, 387 arcsine function, 349 arithmetic sequence, 208 arrow diagram,

More information

Boolean Algebra Part 1

Boolean Algebra Part 1 Boolean Algebra Part 1 Page 1 Boolean Algebra Objectives Understand Basic Boolean Algebra Relate Boolean Algebra to Logic Networks Prove Laws using Truth Tables Understand and Use First Basic Theorems

More information

Lecture Notes in Discrete Mathematics. Marcel B. Finan Arkansas Tech University c All Rights Reserved

Lecture Notes in Discrete Mathematics. Marcel B. Finan Arkansas Tech University c All Rights Reserved Lecture Notes in Discrete Mathematics Marcel B. Finan Arkansas Tech University c All Rights Reserved 2 Preface This book is designed for a one semester course in discrete mathematics for sophomore or junior

More information

1.5 Methods of Proof INTRODUCTION

1.5 Methods of Proof INTRODUCTION 1.5 Methods of Proof INTRODUCTION Icon 0049 Two important questions that arise in the study of mathematics are: (1) When is a mathematical argument correct? (2) What methods can be used to construct mathematical

More information

1 Propositional Logic

1 Propositional Logic 1 Propositional Logic Propositions 1.1 Definition A declarative sentence is a sentence that declares a fact or facts. Example 1 The earth is spherical. 7 + 1 = 6 + 2 x 2 > 0 for all real numbers x. 1 =

More information

conditional statement conclusion Vocabulary Flash Cards Chapter 2 (p. 66) Chapter 2 (p. 69) Chapter 2 (p. 66) Chapter 2 (p. 76)

conditional statement conclusion Vocabulary Flash Cards Chapter 2 (p. 66) Chapter 2 (p. 69) Chapter 2 (p. 66) Chapter 2 (p. 76) biconditional statement conclusion Chapter 2 (p. 69) conditional statement conjecture Chapter 2 (p. 76) contrapositive converse Chapter 2 (p. 67) Chapter 2 (p. 67) counterexample deductive reasoning Chapter

More information

DISCRETE MATH: LECTURE 4

DISCRETE MATH: LECTURE 4 DISCRETE MATH: LECTURE 4 DR. DANIEL FREEMAN 1. Chapter 3.1 Predicates and Quantified Statements I A predicate is a sentence that contains a finite number of variables and becomes a statement when specific

More information

Problems on Discrete Mathematics 1

Problems on Discrete Mathematics 1 Problems on Discrete Mathematics 1 Chung-Chih Li 2 Kishan Mehrotra 3 L A TEX at July 18, 2007 1 No part of this book can be reproduced without permission from the authors 2 Illinois State University, Normal,

More information

Basic Proof Techniques

Basic Proof Techniques Basic Proof Techniques David Ferry dsf43@truman.edu September 13, 010 1 Four Fundamental Proof Techniques When one wishes to prove the statement P Q there are four fundamental approaches. This document

More information

Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 2

Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 2 CS 70 Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 2 Proofs Intuitively, the concept of proof should already be familiar We all like to assert things, and few of us

More information

Florida State University Course Notes MAD 2104 Discrete Mathematics I

Florida State University Course Notes MAD 2104 Discrete Mathematics I Florida State University Course Notes MAD 2104 Discrete Mathematics I Florida State University Tallahassee, Florida 32306-4510 Copyright c 2011 Florida State University Written by Dr. John Bryant and Dr.

More information

Artificial Intelligence Automated Reasoning

Artificial Intelligence Automated Reasoning Artificial Intelligence Automated Reasoning Andrea Torsello Automated Reasoning Very important area of AI research Reasoning usually means deductive reasoning New facts are deduced logically from old ones

More information

Problems on Discrete Mathematics 1

Problems on Discrete Mathematics 1 Problems on Discrete Mathematics 1 Chung-Chih Li 2 Kishan Mehrotra 3 Syracuse University, New York L A TEX at January 11, 2007 (Part I) 1 No part of this book can be reproduced without permission from

More information

2. Methods of Proof Types of Proofs. Suppose we wish to prove an implication p q. Here are some strategies we have available to try.

2. Methods of Proof Types of Proofs. Suppose we wish to prove an implication p q. Here are some strategies we have available to try. 2. METHODS OF PROOF 69 2. Methods of Proof 2.1. Types of Proofs. Suppose we wish to prove an implication p q. Here are some strategies we have available to try. Trivial Proof: If we know q is true then

More information

1. Use the following truth table to answer the questions.

1. Use the following truth table to answer the questions. Topic 3: Logic 3.3 Introduction to Symbolic Logic Negation and Conjunction Disjunction and Exclusive Disjunction 3.4 Implication and Equivalence Disjunction and Exclusive Disjunction Truth Tables 3.5 Inverse,

More information

INTRODUCTORY SET THEORY

INTRODUCTORY SET THEORY M.Sc. program in mathematics INTRODUCTORY SET THEORY Katalin Károlyi Department of Applied Analysis, Eötvös Loránd University H-1088 Budapest, Múzeum krt. 6-8. CONTENTS 1. SETS Set, equal sets, subset,

More information

Proof: A logical argument establishing the truth of the theorem given the truth of the axioms and any previously proven theorems.

Proof: A logical argument establishing the truth of the theorem given the truth of the axioms and any previously proven theorems. Math 232 - Discrete Math 2.1 Direct Proofs and Counterexamples Notes Axiom: Proposition that is assumed to be true. Proof: A logical argument establishing the truth of the theorem given the truth of the

More information

Quantifiers are used to describe variables in statements. - The universal quantifier means for all. - The existential quantifier means there exists.

Quantifiers are used to describe variables in statements. - The universal quantifier means for all. - The existential quantifier means there exists. 11 Quantifiers are used to describe variables in statements. - The universal quantifier means for all. - The existential quantifier means there exists. The phrases, for all x in R if x is an arbitrary

More information

What is logic? Propositional Logic. Negation. Propositions. This is a contentious question! We will play it safe, and stick to:

What is logic? Propositional Logic. Negation. Propositions. This is a contentious question! We will play it safe, and stick to: Propositional Logic This lecture marks the start of a new section of the course. In the last few lectures, we have had to reason formally about concepts. This lecture introduces the mathematical language

More information

Computing Science 272 Solutions to Midterm Examination I Tuesday February 8, 2005

Computing Science 272 Solutions to Midterm Examination I Tuesday February 8, 2005 Computing Science 272 Solutions to Midterm Examination I Tuesday February 8, 2005 Department of Computing Science University of Alberta Question 1. 8 = 2+2+2+2 pts (a) How many 16-bit strings contain exactly

More information

MODULAR ARITHMETIC. a smallest member. It is equivalent to the Principle of Mathematical Induction.

MODULAR ARITHMETIC. a smallest member. It is equivalent to the Principle of Mathematical Induction. MODULAR ARITHMETIC 1 Working With Integers The usual arithmetic operations of addition, subtraction and multiplication can be performed on integers, and the result is always another integer Division, on

More information

LOGICAL INFERENCE & PROOFs. Debdeep Mukhopadhyay Dept of CSE, IIT Madras

LOGICAL INFERENCE & PROOFs. Debdeep Mukhopadhyay Dept of CSE, IIT Madras LOGICAL INFERENCE & PROOFs Debdeep Mukhopadhyay Dept of CSE, IIT Madras Defn A theorem is a mathematical assertion which can be shown to be true. A proof is an argument which establishes the truth of a

More information

Definition: Group A group is a set G together with a binary operation on G, satisfying the following axioms: a (b c) = (a b) c.

Definition: Group A group is a set G together with a binary operation on G, satisfying the following axioms: a (b c) = (a b) c. Algebraic Structures Abstract algebra is the study of algebraic structures. Such a structure consists of a set together with one or more binary operations, which are required to satisfy certain axioms.

More information

6.080/6.089 GITCS Feb 12, 2008. Lecture 3

6.080/6.089 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 information

Propositional Logic. A proposition is a declarative sentence (a sentence that declares a fact) that is either true or false, but not both.

Propositional Logic. A proposition is a declarative sentence (a sentence that declares a fact) that is either true or false, but not both. irst Order Logic Propositional Logic A proposition is a declarative sentence (a sentence that declares a fact) that is either true or false, but not both. Are the following sentences propositions? oronto

More information

Geometry Chapter 2: Geometric Reasoning Lesson 1: Using Inductive Reasoning to Make Conjectures Inductive Reasoning:

Geometry Chapter 2: Geometric Reasoning Lesson 1: Using Inductive Reasoning to Make Conjectures Inductive Reasoning: Geometry Chapter 2: Geometric Reasoning Lesson 1: Using Inductive Reasoning to Make Conjectures Inductive Reasoning: Conjecture: Advantages: can draw conclusions from limited information helps us to organize

More information

-123- A Three-Valued Interpretation for a Relevance Logic. In thi.s paper an entailment relation which holds between certain

-123- A Three-Valued Interpretation for a Relevance Logic. In thi.s paper an entailment relation which holds between certain Dr. Frederick A. Johnson Department of Philosophy Colorado State University Fort Collins, Colorado 80523-23- A Three-Valued Interpretation for a Relevance Logic In thi.s paper an entailment relation which

More information

Lecture 12. More algebra: Groups, semigroups, monoids, strings, concatenation.

Lecture 12. More algebra: Groups, semigroups, monoids, strings, concatenation. V. Borschev and B. Partee, November 1, 2001 p. 1 Lecture 12. More algebra: Groups, semigroups, monoids, strings, concatenation. CONTENTS 1. Properties of operations and special elements...1 1.1. Properties

More information

WOLLONGONG COLLEGE AUSTRALIA. Diploma in Information Technology

WOLLONGONG COLLEGE AUSTRALIA. Diploma in Information Technology First Name: Family Name: Student Number: Class/Tutorial: WOLLONGONG COLLEGE AUSTRALIA A College of the University of Wollongong Diploma in Information Technology Final Examination Spring Session 2008 WUCT121

More information

8.7 Mathematical Induction

8.7 Mathematical Induction 8.7. MATHEMATICAL INDUCTION 8-135 8.7 Mathematical Induction Objective Prove a statement by mathematical induction Many mathematical facts are established by first observing a pattern, then making a conjecture

More information

Definition of Statement: A group words or symbols that can be classified as true or false.

Definition of Statement: A group words or symbols that can be classified as true or false. Logic Math 116 Section 3.1 Logic and Statements Statements Definition of Statement: A group words or symbols that can be classified as true or false. Examples of statements Violets are blue Five is a natural

More information

= 2 + 1 2 2 = 3 4, Now assume that P (k) is true for some fixed k 2. This means that

= 2 + 1 2 2 = 3 4, Now assume that P (k) is true for some fixed k 2. This means that Instructions. Answer each of the questions on your own paper, and be sure to show your work so that partial credit can be adequately assessed. Credit will not be given for answers (even correct ones) without

More information

Vocabulary. Term Page Definition Clarifying Example. biconditional statement. conclusion. conditional statement. conjecture.

Vocabulary. Term Page Definition Clarifying Example. biconditional statement. conclusion. conditional statement. conjecture. CHAPTER Vocabulary The table contains important vocabulary terms from Chapter. As you work through the chapter, fill in the page number, definition, and a clarifying example. biconditional statement conclusion

More information

WOLLONGONG COLLEGE AUSTRALIA. Diploma in Information Technology

WOLLONGONG COLLEGE AUSTRALIA. Diploma in Information Technology First Name: Family Name: Student Number: Class/Tutorial: WOLLONGONG COLLEGE AUSTRALIA A College of the University of Wollongong Diploma in Information Technology Mid-Session Test Summer Session 008-00

More information

WHAT ARE MATHEMATICAL PROOFS AND WHY THEY ARE IMPORTANT?

WHAT ARE MATHEMATICAL PROOFS AND WHY THEY ARE IMPORTANT? WHAT ARE MATHEMATICAL PROOFS AND WHY THEY ARE IMPORTANT? introduction Many students seem to have trouble with the notion of a mathematical proof. People that come to a course like Math 216, who certainly

More information

1.3 Induction and Other Proof Techniques

1.3 Induction and Other Proof Techniques 4CHAPTER 1. INTRODUCTORY MATERIAL: SETS, FUNCTIONS AND MATHEMATICAL INDU 1.3 Induction and Other Proof Techniques The purpose of this section is to study the proof technique known as mathematical induction.

More information

Math 55: Discrete Mathematics

Math 55: Discrete Mathematics Math 55: Discrete Mathematics UC Berkeley, Fall 2011 Homework # 1, due Wedneday, January 25 1.1.10 Let p and q be the propositions The election is decided and The votes have been counted, respectively.

More information

CSL105: Discrete Mathematical Structures. Ragesh Jaiswal, CSE, IIT Delhi

CSL105: Discrete Mathematical Structures. Ragesh Jaiswal, CSE, IIT Delhi Propositional Logic: logical operators Negation ( ) Conjunction ( ) Disjunction ( ). Exclusive or ( ) Conditional statement ( ) Bi-conditional statement ( ): Let p and q be propositions. The biconditional

More information

2.) 5000, 1000, 200, 40, 3.) 1, 12, 123, 1234, 4.) 1, 4, 9, 16, 25, Draw the next figure in the sequence. 5.)

2.) 5000, 1000, 200, 40, 3.) 1, 12, 123, 1234, 4.) 1, 4, 9, 16, 25, Draw the next figure in the sequence. 5.) Chapter 2 Geometry Notes 2.1/2.2 Patterns and Inductive Reasoning and Conditional Statements Inductive reasoning: looking at numbers and determining the next one Conjecture: sometimes thought of as an

More information

Introduction to mathematical arguments

Introduction to mathematical arguments Introduction to mathematical arguments (background handout for courses requiring proofs) by Michael Hutchings A mathematical proof is an argument which convinces other people that something is true. Math

More information

3. Mathematical Induction

3. Mathematical Induction 3. MATHEMATICAL INDUCTION 83 3. Mathematical Induction 3.1. First Principle of Mathematical Induction. Let P (n) be a predicate with domain of discourse (over) the natural numbers N = {0, 1,,...}. If (1)

More information

Direct Proofs. CS 19: Discrete Mathematics. Direct Proof: Example. Indirect Proof: Example. Proofs by Contradiction and by Mathematical Induction

Direct Proofs. CS 19: Discrete Mathematics. Direct Proof: Example. Indirect Proof: Example. Proofs by Contradiction and by Mathematical Induction Direct Proofs CS 19: Discrete Mathematics Amit Chakrabarti Proofs by Contradiction and by Mathematical Induction At this point, we have seen a few examples of mathematical proofs. These have the following

More information

DISCRETE MATHEMATICS W W L CHEN. c W W L Chen, 1982.

DISCRETE MATHEMATICS W W L CHEN. c W W L Chen, 1982. DISCRETE MATHEMATICS W W L CHEN c W W L Chen, 982. This work is available free, in the hope that it will be useful. Any part of this work may be reproduced or transmitted in any form or by any means, electronic

More information

Foundations of Logic and Mathematics

Foundations of Logic and Mathematics Yves Nievergelt Foundations of Logic and Mathematics Applications to Computer Science and Cryptography Birkhäuser Boston Basel Berlin Contents Preface Outline xiii xv A Theory 1 0 Boolean Algebraic Logic

More information

Math 313 Lecture #10 2.2: The Inverse of a Matrix

Math 313 Lecture #10 2.2: The Inverse of a Matrix Math 1 Lecture #10 2.2: The Inverse of a Matrix Matrix algebra provides tools for creating many useful formulas just like real number algebra does. For example, a real number a is invertible if there is

More information

1.2 Truth and Sentential Logic

1.2 Truth and Sentential Logic Chapter 1 Mathematical Logic 13 69. Assume that B has m left parentheses and m right parentheses and that C has n left parentheses and n right parentheses. How many left parentheses appear in (B C)? How

More information

Review Name Rule of Inference

Review Name Rule of Inference CS311H: Discrete Mathematics Review Name Rule of Inference Modus ponens φ 2 φ 2 Modus tollens φ 2 φ 2 Inference Rules for Quantifiers Işıl Dillig Hypothetical syllogism Or introduction Or elimination And

More information

MATHS 315 Mathematical Logic

MATHS 315 Mathematical Logic MATHS 315 Mathematical Logic Second Semester, 2006 Contents 2 Formal Statement Logic 1 2.1 Post production systems................................. 1 2.2 The system L.......................................

More information

Mathematical Induction

Mathematical Induction Mathematical Induction MAT30 Discrete Mathematics Fall 016 MAT30 (Discrete Math) Mathematical Induction Fall 016 1 / 19 Outline 1 Mathematical Induction Strong Mathematical Induction MAT30 (Discrete Math)

More information

Chapter 3. Cartesian Products and Relations. 3.1 Cartesian Products

Chapter 3. Cartesian Products and Relations. 3.1 Cartesian Products Chapter 3 Cartesian Products and Relations The material in this chapter is the first real encounter with abstraction. Relations are very general thing they are a special type of subset. After introducing

More information

Logic in Computer Science: Logic Gates

Logic in Computer Science: Logic Gates Logic in Computer Science: Logic Gates Lila Kari The University of Western Ontario Logic in Computer Science: Logic Gates CS2209, Applied Logic for Computer Science 1 / 49 Logic and bit operations Computers

More information

Logic in general. Inference rules and theorem proving

Logic in general. Inference rules and theorem proving Logical Agents Knowledge-based agents Logic in general Propositional logic Inference rules and theorem proving First order logic Knowledge-based agents Inference engine Knowledge base Domain-independent

More information

Statements, negations, connectives, truth tables, equivalent statements, De Morgan s Laws, arguments, Euler diagrams

Statements, negations, connectives, truth tables, equivalent statements, De Morgan s Laws, arguments, Euler diagrams Logic Statements, negations, connectives, truth tables, equivalent statements, De Morgan s Laws, arguments, Euler diagrams Part 1: Statements, Negations, and Quantified Statements A statement is a sentence

More information

2.1 Simple & Compound Propositions

2.1 Simple & Compound Propositions 2.1 Simle & Comound Proositions 1 2.1 Simle & Comound Proositions Proositional Logic can be used to analyse, simlify and establish the equivalence of statements. A knowledge of logic is essential to the

More information

Section 1.3: Predicate Logic

Section 1.3: Predicate Logic 1 Section 1.3: Purpose of Section: To introduce predicate logic (or first-order logic) which the language of mathematics. We see how predicate logic extends the language of sentential calculus studied

More information

Beyond Propositional Logic Lukasiewicz s System

Beyond Propositional Logic Lukasiewicz s System Beyond Propositional Logic Lukasiewicz s System Consider the following set of truth tables: 1 0 0 1 # # 1 0 # 1 1 0 # 0 0 0 0 # # 0 # 1 0 # 1 1 1 1 0 1 0 # # 1 # # 1 0 # 1 1 0 # 0 1 1 1 # 1 # 1 Brandon

More information

Arkansas Tech University MATH 4033: Elementary Modern Algebra Dr. Marcel B. Finan

Arkansas Tech University MATH 4033: Elementary Modern Algebra Dr. Marcel B. Finan Arkansas Tech University MATH 4033: Elementary Modern Algebra Dr. Marcel B. Finan 3 Binary Operations We are used to addition and multiplication of real numbers. These operations combine two real numbers

More information

Exam 2 Review Problems

Exam 2 Review Problems MATH 1630 Exam 2 Review Problems Name Decide whether or not the following is a statement. 1) 8 + 5 = 14 A) Statement B) Not a statement 1) 2) My favorite baseball team will win the pennant. A) Statement

More information

Properties of Real Numbers

Properties of Real Numbers 16 Chapter P Prerequisites P.2 Properties of Real Numbers What you should learn: Identify and use the basic properties of real numbers Develop and use additional properties of real numbers Why you should

More information

Applications of Methods of Proof

Applications of Methods of Proof CHAPTER 4 Applications of Methods of Proof 1. Set Operations 1.1. Set Operations. The set-theoretic operations, intersection, union, and complementation, defined in Chapter 1.1 Introduction to Sets are

More information

CHAPTER 5: MODULAR ARITHMETIC

CHAPTER 5: MODULAR ARITHMETIC CHAPTER 5: MODULAR ARITHMETIC LECTURE NOTES FOR MATH 378 (CSUSM, SPRING 2009). WAYNE AITKEN 1. Introduction In this chapter we will consider congruence modulo m, and explore the associated arithmetic called

More information

Mathematical induction. Niloufar Shafiei

Mathematical induction. Niloufar Shafiei Mathematical induction Niloufar Shafiei Mathematical induction Mathematical induction is an extremely important proof technique. Mathematical induction can be used to prove results about complexity of

More information