Reading (in lieu of class on Thursday, September 16^th)

and

Assignment based on the reading which is due on September 21^st

Carefully read Section 3.1 of our text (pages 163-178)

Work through the Examples and the Practices. Make a careful note of those that do not make sense to you after reading them several times.

Copy and complete the three column table below in which the left most column contains the terms below, the middle column contains their definition from the book and the right most column contains the page where the definition can be found. Print it out and bring it to class.

Term	Definition	Page #
binary operation	∘ is an binary operation on a set S if for every ordered pair (x,y) of elements of S, x ∘ y exists, is unique, and is a member of S	169
cardinality of a set	number of elements in a finite set	175
Cartesian product of sets A and B	is A X B - the set of all ordered pairs (x,y) such that x is an element of A and y is an element of B. (cross product)	173
cross product of sets A and B	is A X B - the set of all ordered pairs (x,y) such that x is an element of A and y is an element of B. (Cartesian product)	173
closed set under an operation ∘	if for every ordered pair (x, y) of elements of S, x ∘ y always belongs to S.	169
complement of a set	For a set A which is a subset of S, the complement of A, A' is the set of all elements in S which are not in A	171
countable set	a set is countable if we can show "here is a first element, here is a second element, and so on through the set " doesn't mean we can list all the elements	176
denumerable set	infinite set for whose elements we can show an enumeration of all their elements (is a countable set)	176
disjoint sets	sets A and B which have no elements in common (two sets whose intersection is the empty set)	172
dual of a set identity	is obtained by interchanging ∪ and ∩ and by interchanging S and ∅	175
empty set	is a set with no elements (a null set)	165
equal sets	two sets are equal if and only if they contain the same elements	164
finite set	is a set, all of whose elements could be listed (is a countable set)	164
infinite set	is a set, all of whose elements couldn't be listed (may be countable)	164
intersection of sets	set of all elements x such that x is in set A and x is in set B	171
null set	set with no elements (an empty set)	165
ordered pair	denoted by (x,y) where x is the first component of the ordered pair and y is the second component (order matters)	168
power set	of S is a set whose elements are all of the subsets of S	168
proper subset	set A is a proper subset of set B if there is at least one element in set B that is not in set A. (i.e. set A is not equal to set B)	166
set difference	A-B is the set of all elements x such that x is in A and x is not in B	172
subset	setA is a subset of set B if every member of A is also a member of B	166
unary operation	for any x^# in S, ^# is well defined and S is closed under ^# x^# exists, is unique, and is a member of S	170
uncountable set	is a set that is so big that there is no way to count the elements	176
union of sets	set of all elements x such that x is in set A or x is in set B or x is in both set A and set B	171
universal set	context of an arbitrary set S (universe of discourse)	170
universe of discourse	context of an arbitrary set S (universe of discourse)	170
well defined operation	if x∘y always exists and is unique, then ∘ is well defined	169

Copy the following table and complete it by identifying the symbols in the leftmost column.

Print it and bring it to class

Symbol	Meaning
⊂	proper subset of
∅	null set
∀	for all
ℕ	set of all nonnegative integers
ℝ	set pf all real numbers
ℤ	set of all integers
ℚ	set of all rational numbers
ℂ	set of all complex numbers
∈	element of
∉	not an element of
∃	there exists
{ }	null set
⊆	subset of
℘	power set
∩	intersection
∪	union
∘	operation

NOTE: Some problems for you to do and turn in will be added to this page.

Exercises 3.1

2a

2b

5a

6a

9a

10a

10d

10g

21

30

SEE BELOW FOR A SCREEN SHOT OF THE TABLE WITH SYMBOLS IN IT… SHOW IT AT 150% TO MAKE THE SYMBOLS

CLEARER