Test 1 Flashcards
Upper Bound/Bounded Above
Chp 1
Definition
A number M is said to be an upper bound of E if x<=M for all x in E
Lower Bound/Bounded Below
Chp 1
Definition
A number m is said to be a lower bound of E if m<=x for all x in E
Maximum
Chp 1
Definition
If there exists a number M in E that is larger than every other member of E, then M is called the maximum of E
M=max(E)
Minimum
Chp 1
Definition
If there exists a number m in E that is smaller than every other member of E, then m is called the minimum of E
m=min(E)
Supremum
Chp 1
Definition
If E is bounded above and non-empty and M is the least upper bound, then M is the supremum of E
M=sup(E)
Infimum
Chp 1
Definition
If E is bounded below and non-empty and m is the greatest lower bound, then m is the infimum of E
m=inf(E)
The Completeness Axiom (Upper)
Chp 1
A non-empty set of Reals that is bounded above has a least upper bound
Hence, sup(E) exists
The Completeness Axiom (Lower)
Chp 1
A non-empty set of Reals that is bounded below has a greatest lower bound
Hence, inf(E) exists
Archimedean Properties
Chp 1
Theorem
1) The set of Natural numbers has no upper bound
2) No matter how large a Real x is, there is always a Natural n that is larger
3) No matter how large y>0 is and how small x>0 is, there exists a Natural n such that nx>y
4) No matter how small x>0 is, there exists a fraction (1/n)<x
Well-Ordering Property
Chp 1
Theorem
Every non-empty subset of Naturals has a smallest element
Dense Sets
Chp 1
Definition
A set of Reals, E, is said to be dense if every interval (a,b) contains a point of E
What is the definition of Absolute Value?
Chp 1
Definition
|x| = x if x >= 0
|x| = -x if x < 0
Absolute Value Properties
Chp 1
Theorem
For any x in R:
1) -|x| <= x <= |x|
2) |xy| = |x||y|
3) |x + y| <= |x| + |y|
4) |x| - |y| <= |x-y|
and
|x - y| >= |y| - |x|
What is the distance between two real numbers?
Chp 1
Definition
d(x,y) = |x - y|
What does a Sequence of Real numbers represent?
Chp 2
Definition
A sequence of Real numbers is a function f:N==>R
What is Cantor’s Theorem?
Chp 2
Theorem
No interval (a,b) of Reals can be the range of some sequence
Countable
Chp 2
Definition
A subset of Reals, S, is said to be countable if there is a sequence of Real numbers whose range is S
Limit of a Sequence
Chp 2
Definition
If {Sn} is a sequence of Real numbers, we say {Sn} converges to a number L if for all epsilon>0, there exists N such that
|Sn-L|<epsilon>=N</epsilon>
Lim Sn = L
Uniqueness of Limits
Chp 2
Theorem
If Lim Sn= L
and
Lim Sn=W
Then L=W
Divergence
Chp 2
Definition
If {Sn} is a sequence of Reals, we say {Sn} diverges to (inf) if for every M there exists an N so that Sn>=M whenever n>=N
Lim Sn = (inf)
What can you say about convergent sequences?
Chp 2
Theorem
They are bounded
Lim cSn = ?
Chp 2
Theorem
c(Lim Sn)
Lim (Sn+Tn) = ?
Chp 2
Theorem
Lim Sn + Lim Tn
Lim (Sn/Tn) = ?
Chp 2
Theorem
(Lim Sn)/(Lim Tn)
If {Sn} and {Tn} converge, and Sn<=Tn for all n, what can you say about the limits?
Chp 2
Theorem
Lim Sn <= Lim Tn
If {Sn} converges and
a <= Sn <= b, what can you say about Lim Sn?
Chp 2
Theorem (Corollary)
a <= Lim Sn <= b
If {Sn} and {Tn} converge
and
Lim Sn = Lim Tn for all n
and
Sn <= Xn <= Tn then…?
Chp 2
Squeeze Theorem
Lim Sn = Lim Xn = Lim Tn
What is the limit of absolute values?
Chp 2
Theorem
The absolute value of the limit
What is the Max/Min of a Limit?
Chp 2
Theorem (Corollary)
Lim Max{Sn,Tn}
Max{Lim Sn, Lim Tn}
What is an increasing sequence?
Chp 2
Definition
S1 < S2 < … < Sn < …
What is a non-decreasing sequence?
Chp 2
Definition
S1 <= S2 <= … <= Sn <= ..
What is a decreasing sequence?
Chp 2
Definition
S1 > S2 > … > Sn > …
What is a non-increasing sequence?
Chp 2
Definition
S1 >= S2 >= … >= Sn >= ..
What is a monotonic sequence?
Chp 2
Definition
Any sequence that is non-increasing or non-decreasing (including increasing and decreasing)
What is the Monotone Convergence Theorem?
Chp 2
Theorem
If {Sn} is a monotonic sequence, then {Sn} converges iff {Sn} is bounded
If {Sn} is bounded and non-decreasing, what can you say?
Chp 2
Theorem
Since it is monotonic,
{Sn} ==> sup(Sn)
If {Sn} is bounded and non-increasing, what can you say?
Chp 2
Theorem
Since it is monotonic,
{Sn} ==> inf(Sn)
What is a subsequence?
Chp 2
Definition
If S1, S2, … is a sequence, then a subsequence exists S_n1, S_n2, … where n1 < n2 < …
Hence, n1, n2, … is a sequence of increasing Natural numbers
Every sequence contains a _________ subsequence
Chp 2
Theorem
monotonic
Bolzano-Weierstrass Theorem
Chp 2
Theorem
Every bounded sequence contains a convergent subsequence
Cauchy Criterion
Chp 2
Theorem
A sequence {Sn} is convergent iff for each epsilon>0, there exists N such that |Sn - Sm|<epsilon, for all n,m>=N