Lecture 2: Asymptotic Notation, Recurrences, Substitution, Master Method

author:Erik Demaine, Center for Future Civic Media
published: Feb. 10, 2009,   recorded: September 2005,   views: 3547
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Slides

Slides
0:00 Introduction to Algorithms - Lecture 2
1:07 Asymptotic notation (1)
2:47 Asymptotic notation (2)
3:47 Asymptotic notation (3)
3:48 Asymptotic notation (4)
3:55 Set definition of O-notation (1)
4:40 Set definition of O-notation (2)
4:55 Set definition of O-notation (3)
5:14 Macro substitution (1)
6:26 Macro substitution (2)
7:59 Macro substitution (3)
10:24 Ω-notation (lower bounds) (1)
10:32 Ω-notation (lower bounds) (2)
11:16 Ω-notation (lower bounds) (3)
12:22 Θ-notation (tight bounds) (1)
13:22 Θ-notation (tight bounds) (2)
13:32 ο-notation and ω-notation (1)
14:30 ο-notation and ω-notation (2)
16:51 Solving recurrences
17:15 Substitution method (1)
18:52 Substitution method (2)
23:19 Example of substitution (1)
27:12 Example of substitution (2)
28:18 Example of substitution (3)
28:41 A tighter upper bound (1)
28:54 A tighter upper bound (2)
29:55 A tighter upper bound (3)
30:13 A tighter upper bound (4)
30:54 A tighter upper bound (5)
31:53 A tighter upper bound (6)
34:05 A tighter upper bound (7)
37:39 Recursion-tree method
38:52 Example of recursion tree (1)
40:07 Example of recursion tree (2)
40:09 Example of recursion tree (3)
40:39 Example of recursion tree (4)
41:05 Example of recursion tree (5)
41:19 Example of recursion tree (6)
43:54 Example of recursion tree (7)
44:21 Example of recursion tree (8)
45:37 Example of recursion tree (9)
48:51 The master method
51:45 Three common cases (1)
53:30 Three common cases (2)
54:56 Three common cases (3)
57:25 Examples (1)
58:47 Examples (2)
59:44 Examples (3)
60:01 Examples (4)
61:49 Idea of master theorem (1)
63:22 Idea of master theorem (2)
65:54 Idea of master theorem (3)
66:15 Idea of master theorem (4)
66:56 Idea of master theorem (5)
68:15 Idea of master theorem (6)

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Description

"My name is Erik Demaine. You should call me Erik. Welcome back to 6.046. This is Lecture 2. And today we are going to essentially fill in some of the more mathematical underpinnings of Lecture 1. So, Lecture 1, we just sort of barely got our feet wet with some analysis of algorithms, insertion sort and mergesort. And we needed a couple of tools. We had this big idea of asymptotics and forgetting about constants, just looking at the lead term. And so, today, we're going to develop asymptotic notation so that we know that mathematically. And we also ended up with a recurrence with mergesort, the running time of mergesort, so we need to see how to solve recurrences. And we will do those two things today. Question? Yes, I will speak louder. Thanks. Good..."

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Reviews and comments:

Comment1 peter, June 28, 2009 at 4:08 p.m.:

test


Comment2 ayaz, October 29, 2009 at 9:28 p.m.:

i want to know about recurences


Comment3 Sally, January 4, 2010 at 12:10 p.m.:

this helped me a lot... thank u Dr. Erik so much


Comment4 mark, February 2, 2010 at 10:09 p.m.:

Beware of "f(n) = O(g(n)" since it is NOT really true.

Instead, the "belongs to" symbol ("∈") should be used.

Please take a look at:

http://en.wikipedia.org/wiki/O_notati...

where it states:
'Note that "=" is not meant to express "is equal to" in its normal mathematical sense, but rather a more colloquial "is" [...]'

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