On completion of this unit successful students will be able to:
analyze statements using truth tables;
construct simple proofs including proofs by contradiction and proofs by induction;
prove statements about sets and functions;
prove standard results about countable sets;
apply Euclid 's Algorithm to find the greatest common divisor of pairs of integers and to solve linear Diophantine equations;
to solve simultaneous linear congruences;
multiply and factorize permutations;
prove the infinitude of prime numbers, prove Fermat's Little Theorem and use it to find modular inverses and to solve linear congruences;
construct multiplication tables for congruence classes, reduced congruence classes and sets of permutations. Have an informal understanding of isomorphisms between the groups seen in the course.
Syllabus (Part 1: Nige Ray)
This covers chapters 1 to 14 of the course text omitting 5.4, 9.4, 11.3, 12.1, 12.2 and 12.3.
Lecture 0: Provocative Examples. First thoughts on infinite sets; examples versus proof; an extended version of Hilbert's Hotel; Cantor's fate (and redemption!).
2. Basic Logic
Lecture 1: The Language of Mathematics. Mathematical statements, propositions; or, and, not; truth tables.
Lecture 2: Implication. Implication; necessary and sufficient, iff; rules of arithmetic; where proofs begin.
Lecture 3: Proof. Direct proof; case-by-case; working backwards.
Lecture 4: Contradiction. Negative statements; proof by contradiction; contrapositives; statements with 'or'.
Lecture 5: Induction. The induction principle and proof by induction; changing the base case; inductive definitions.
Lecture 6: History and Language. Historical origins, natural numbers to complex numbers; notation, belongs to, definitions (by listing, by conditions, by construction); subsets, equality.
Lecture 7: Operations on Sets. Union , intersection, empty set (with class discussion!); identities, Venn diagrams; power set.
Lecture 8: Quantifiers. Universal and existential statements, proof and negation of statements with quantifiers; induction revisited; two free variables.
Lecture 9: Further operations. Cartesian products; power sets.
Lecture 10: Definitions and Examples. Notation; domain, codomain; formulae and examples (including empty set); equality; restriction.
Lecture 11: More Definitions and Examples. Composition; image; sequences and indexing; restriction, graphs.
Lecture 12: Jections. Injections, surjections, bijections; their compositions.
Lecture 13: Inverse functions. Bijections and inverse functions; inverse images; transpositions.
6. Counting Finite Sets.
Lecture 14: Cardinality. Role of the integers, cardinality, is it well-defined? reduction to pigeon-hole principle.
Lecture 15: Principles of Counting. Principles of addition, multiplication, inclusion-exclusion.
Lecture 16: The Pigeon-hole Principle. Proof of the pigeon-hole principle, finite sets of real numbers.
7. Counting Infinite Sets.
Lecture 17: Rationals and Reals. Definition of rationals, and of reals as infinite decimals; 2.
Lecture 18: Countability. Denumerability, 0 , proper subsets; Cartesian products, integer pairs, rationals.
Lecture 19: Uncountability. The reals; power sets and their cardinality.
Lecture 20: Other Types of Real Number. Algebraic and transcendental numbers.
Part 2 (Mark Coleman)
1. Counting Collections of Functions and Subsets.
Numbers of injections and bijections. Numbers of subsets and Binomial Numbers, Pascal's Triangle, Binomial Theorem.
2. Arithmetic - the study of the integers.
Division Theorem, greatest common divisor, Euclid 's Algorithm, linear Diophantine equations.
3. Congruence and Congruence Classes.
Congruences, modular arithmetic, solving linear congruences, Chinese remainder theorem, congruence classes, multiplication tables*, invertible elements, reduced systems of classes*.
4. Partitions and Relations.
Partitions, relations, generalizing congruence classes.
Bijections, two row notation, composition, cycles, the permutation group Sn, composition tables, factorization, order.
6. Prime Numbers.
Sieve of Erastosthenes, infinitude of primes, conjectures about primes, Fermat's Little Theorem, Euler's Theorem*.
7. Groups, Rings and Fields*.
Definitions and very simple properties. Examples from earlier in the course, multiplication tables.
*indicates that this topic is not included in the course text.