6. Randomization: Matrix Multiply, Quicksort

[@karthikvasishtaramesh6382]

Quick Sort: 50:24

[@ashfaqrahman2795]

Karthik Vasishta Ramesh Hamere bhagwan Amarendra Baahubali ka raqt ho tum

[@heddygong7416]

Randomized Quick Sort: 1:07:44

[@sumitlahiri4973]

This is most useful post in the whole "comment section".

[@brendawilliams8062]

@@sumitlahiri4973 no. Just to have the chance. I didn’t like the way they add before and still don’t. I Quit. So go ahead. 😂 lol

[@tharunreddy7333]

Thanks!

[@o.y.930]

1:19:43 when my professor sees me entering the classrom

[@seancolandrea1256]

coming to this from 6.006 feels like martin scorsese directed this

[@huecountstudio8796]

MIT has some quality professors, damn. This was very helpful, thank you

[@cybernagle]

randomize quick sort & analysis: 1:07:57

[@adityasanthosh702]

"So If You're going to do the same thing again and again,and expect different results, That's called Insanity"

[@jayeshmarathe7678]

1:07:40 Randomised quicksort

[@oronshifman]

50:00 - quick sort

[@SphereofTime]

2:07 Generate Randomized Algoritm ;Vector,..

[@shah.kairav]

Wasn't the professor correct in making the jth value 1 instead of the ith value as pointed out by one of the students?

[@PierrePark]

the professor was incorrect?

[@hj2931]

I also agree that the professor is correct. For example, if D is a 3 x 2 matrix and v is a 2 x 1 vector, let i = 3, but there is no third row in v.

[@evanpiermont7490]

What is the collection of r vectors? Doesn't the 1-1 mapping argument require that your set of vectors (the support of the randomization) is close under addition by v. But without knowing v ahead of time, this might require an infinite set of vectors, in which case a bijection is not enough to guarantee equal measure between sets.

[@fbrunodr]

• r is simply a R^n vector. • If D is not 0, then there exists a vector v such that Dv /= 0. You don't need to know v, you just need to know there is v. • He is not proving the sets have equal measure. He's proving one set is at least as big as the other.

[@benihananah]

all vectors of size n and entries 0 or 1. it's closed under (+ mod2)

[@mohsennabian9661]

Love double camera!

[@ninjacod2254]

Hi Guys, How different is this course comparing to the Introduction to Algorithms class taught by him?

[@F1mus]

From experience, 6.046 is MUCH harder than 6.006.

[@dharmiknaik1772]

6.006 entails analysing algorithms. This class is concerned with more designing an algo.

[@barsopiavivek]

a lot of freebies this lecture

[@imaddinamsif]

i don't know why i am from spain :( I looked exams from MIT, which were published on official web page and i like it.... Professor? I like how they are proposing some problems and how they teach, This life is not fair, but I will do everything possible to finish and do a master at MIT

[@artificialintelligence3727]

Sorry to break it but MIT gets only PhD as graduate students in CS. Go for a PhD, do research.

[@imaddinamsif]

Brandon Busby i was studing in UPV (Valencia)

[@andrasviczian9262]

Couldn't you just make r a vector of n ones? Then if D is actually all zeros it would give the right answer, and if D has a one at any place it will also give the right answer.

[@luojihencha]

I am wondering as well

[@benihananah]

Take A=[[1, 0], [0, 1]], B = [[1, 1], [0, 0]] and C = [[1, 1], [1, 1]] AB not= C, but Frievald's alg returns YES for r=[1, 1]. The proof shows, however, that there exists an r'=[1, 0] such that Frievald's alg returns NO.

[@jimmypi7]

anyone understand their joke about : probably correct and probably fast algorithm? 111 00:06:56,144 --> 00:06:57,560 which means that they're incorrect 112 00:06:57,560 --> 00:06:59,560 and slow some of the time. 113 00:06:59,560 --> 00:07:00,100 Right? 114 00:07:00,100 --> 00:07:03,900 So what do you think those algorithms are called? 115 00:07:03,900 --> 00:07:04,400 Sorry. 116 00:07:04,400 --> 00:07:05,222 What? 117 00:07:05,222 --> 00:07:06,580 AUDIENCE: T? 118 00:07:06,580 --> 00:07:07,610 SRINIVAS DEVADAS: The T? 119 00:07:07,610 --> 00:07:08,130 Oh. 120 00:07:08,130 --> 00:07:08,330 Oh! 121 00:07:08,330 --> 00:07:09,500 That deserves a Frisbee. 122 00:07:09,500 --> 00:07:10,700 Oh my goodness! 123 00:07:10,700 --> 00:07:11,980 [LAUGHS] All right.

[@jimmypi7]

Prof Srini later mentioned : 133 00:07:37,479 --> 00:07:38,020 So the MB/TA. And I googled MB/TA : kzbin.info/www/bejne/pnunk3ireNdqjKM BOSTON, riding the SUBWAY (THE 'T') from Boston University to Quincy Market (USA) The T is probably boston subway? ps , the following is my google attempts : in reverse chronological order &q=the+t+in+boston& &q=MB%2FTA+the+t+in+boston& &q=MB%2FTA&

[@ChrisSketch89]

They’re making fun of MBTA, the public transit system over by MIT.

[@ChaojianZhang]

This 1080p lecture recording is awesome.

[@ChaojianZhang]

I finally realize those are more like conference presentations.

[@ChaojianZhang]

(Note) If no one asks questions for 90% of the time, we should just make those lectures online-access 90% of the time, and let instructors just do Q&A the rest of the time.

[@ChaojianZhang]

If, however, we can collect all questions specific to a lecture - even that part can be archived.

[@इंसान-न4ढ]

LOL at 1:19:44

[@ayushkapri1857]

Do these lectures only have theory.

[@maashaz]

feels bad that my professor just copy pastes from MIT i dont know why i pay for school...

[@gallerycollection2022]

amaizing

[@veraBeStnews]

Does someone know which book he mentions? CLRS

[@BrandonCGreer]

CLRS is sort of the classic Algorithm book, the letters are the last names of the authors. If you search CLRS pdf, you'll find a link on Github. The third edition is the most recent one, it's more mathematically formal than these lectures.

[@shershahdrimighdelih]

Introduction to Algorithms by Cormen, Leiserson, Rivest, Stein. It's in the readings section of the OCW page corresponding to this course. It's a very good book if you're looking to actually understanding how the algorithms work. But it requires a little background on math. 6.006 covers a third of it, and 6.046 covers another third.

[@mahendraaanjna2005]

What does the T mean?

[@dharmiknaik1772]

They are making fun of the MBTA (public transit system over by MIT).

[@kkartik7]

looks like some documentary

[@VarunRamanathan28031999]

Watch this in 2x speed.

[@shohmansur4603]

Who going to study in MIT ?

[@junweima]

amazing!

[@shahsadponnad6619]

i didnt understand why every one laughed when the student said '"t" .did I miss anything

[@orifmilod3469]

The t stands for transportation in Massachusetts, MBTA (Massachusetts Bay Transportation Authority)

[@shahsadponnad6619]

@@orifmilod3469 thank you. I thought it was some kind of algorithm. 😂

[@TheEmeraldSwordAxe]

These instructors teach the same class again and again, why cant they write without looking at their notes. It seems that if you take away their notes they will be helpless.

[@abdu1998a]

wtf is wrong with checking notes? They don't need to memorize to teach it. They should just understand it that's all. Also, they can probably remember that without looking at the notes but it may take time. Would it be better if they didn't look at the notes but think 10-15 mins everytime they didn't remember a detail?

[@pratikkulkarni891]

One of the main reasons might be that they don't miss out on any topic and be consistent with the notes that they provide to the students.