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Algorithms, by Jeff Erickson

jeffe.cs.illinois.edu

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Re: Algorithms, by Jeff Erickson

#101

Post by mden »

fwip wrote: post #90
jefferickson wrote: post #83

Earlier quoted context omitted.

Hi, I'm the author. If you find any particular claim of "obviousness" unclear, submit an issue request! But please don't confuse "straightforward" with "obvious". Sometimes I deliberately gloss over mechanical details because I think they're a distraction from the main point. I'm NOT claiming that you should immediately know how to fill in the details; I'm claiming that filling in the details is boring.

I would agree that words like "obvious" or "trivial" can be disheartening to a learner. If it's obvious to the reader, they know it whether or not you tell them it's obvious. If it's not obvious to them, then they will try to figure it out. Telling this person "it's obvious" only serves to make them feel bad about not getting it right away.

I felt that way when studying math in college, but after sometime I actually came to like the use of "clearly" and the like as it can be used as a check on whether you've spent enough time internalizing the previous information. It's one thing to have a text or a person hold your hand through algorithms or theorems, it's another to be able to do it yourself. So getting hit with a "clearly" that feels unjustified is often a signal to let go of the guiding hand and go back and review until the statement in question does become clear.

Re: Algorithms, by Jeff Erickson

#102

Post by alfrapi »

primitivesuave wrote: post #66

Jeff Erickson was my algorithms professor in 2012. He exemplifies the articulate, passionate educator that I wish I had for my other CS subjects. I recognize many of these notes having read them many times in preparation for quite difficult exams - a fun anecdote shared among people who've taken the class is the 25% credit given on any exam question just for writing "I don't know", effectively a reward for acknowledg…

I think the rule was you had to attempt at least one question (couldn't say "I don't know" for the whole exam). Am I remembering that correctly?

Re: Algorithms, by Jeff Erickson

#103

Post by _underflow_ »

smarks wrote: post #98
jefferickson wrote: post #86

Earlier quoted context omitted.

Hi, I'm the author. I'm honestly seriously torn about this. There is a serious tension between pedagogical needs of students in formal classrooms and the pedagogical needs of self-learners. I've chosen to aim for the former. Yes, I know it's a bummer. (From experience) providing solutions interferes with the learning process of my own students at Illinois. I have to change up homeworks and exam questions every semest…

Thanks for this explanation. This is one of the things that popped out at me when I looked at the book page. The statement about not providing answers seemed quite dogmatic, and my initial reaction was, why? Turns out it's not so dogmatic, and there's a thoughtful and nuanced explanation. Perhaps you could include some of this on the book page, or provide a link to the explanation elsewhere.

Completely agree - being outside academia has apparently made me ignorant to a lot of the pitfalls to actually posting said solutions.

Makes perfect sense when put this way.

I also really appreciate the response from the author. I forget the gurus behind books like this often have a presence here on HN.

Re: Algorithms, by Jeff Erickson

#104

Post by 8732332 »

jefferickson wrote: post #93
yoler wrote: post #9

Isn’t this the guy that is famous for being admitted to a PhD program with an exceptionally low GPA? If so, why is he the exception and why aren’t more PhD programs looking for non-traditional talent? Edit: I read his blog post. It gave me more insight. It looks possible for people with those sort of grades to be admitted even today, but they seem to need a cheerleader on the inside that will help them.

Yes, that's me. Admissions committees are looking for evidence of future success. Admitting applicants with spotty (not merely "nontraditional") backgrounds is risky -- they might be a diamond in the rough, or they might really be a weak student. And (at least departments like mine) there are far too many applicants with stellar backgrounds to justify taking that risk. At least, that's the usual argument.

Would you take a risk on someone that graduated with below a 3.0 GPA with Cs in their math/computer science courses, but went back to school, took some core CS courses, aced them, got some research experience, and then applied to PhD programs?

Re: Algorithms, by Jeff Erickson

#106

Post by CydeWeys »

jimhefferon wrote: post #51
kyteland wrote: post #45

Earlier quoted context omitted.

I took CS 173 and 373 from Jeff nearly 20 years ago, with 273 from another great professor. That course sequence along with Combinatorial Game Theory (which I took on a lark) has had a greater impact on me than the rest of my university experience combined. A lot of that is due to the quality of the professors I was lucky enough to have.

Perhaps you might, when you get a chance, email him a brief note to tell him that. That'll make a person's day.

He's in the comments here so I suspect his day is already made! :)

Re: Algorithms, by Jeff Erickson

#107

Post by kyteland »

CydeWeys wrote: post #106
jimhefferon wrote: post #51

Earlier quoted context omitted.

Perhaps you might, when you get a chance, email him a brief note to tell him that. That'll make a person's day.

He's in the comments here so I suspect his day is already made! :)

Yeah, this may the 3rd or 4th time I've said something along those lines in a HN thread he's active in over the last 10 years.

Re: Algorithms, by Jeff Erickson

#108

Post by rbkillea »

This has always bugged me: what reasons outside of convention do we have for preferring O(V + E) to O(E) on algorithms that only make sense in the context of a single connected component? I know this is slightly OT, but tangentially related.

Re: Algorithms, by Jeff Erickson

#109

Post by saagarjha »

bradleyjg wrote: post #99
kemiller2002 wrote: post #62

Earlier quoted context omitted.

I had a girlfriend who was doing her PhD in Physics. I remember one night she and her classmates spent all night working on a problem, that was essentially unsolvable. The next day they go to class and all of them made their best attempt, but no one could complete it. The problem? The professor accidentally used the wrong metric on one of the numbers meaning that they couldn't do the steps to what should have been an…

I had a similar thing happen in high school physics. We were were suppose to figure out where and when a projectile was going to land. The only problem was that it was never going to land—-the initial velocity was too high. In retrospect I think it was a great lesson for my future career as a data engineer. Doesn’t matter what the source is, any datum can be just plain wrong.

> The only problem was that it was never going to land—-the initial velocity was too high.

As in, it escaped the gravitational field?

Re: Algorithms, by Jeff Erickson

#110

Post by saagarjha »

daveFNbuck wrote: post #68
kemiller2002 wrote: post #62

Earlier quoted context omitted.

I had a girlfriend who was doing her PhD in Physics. I remember one night she and her classmates spent all night working on a problem, that was essentially unsolvable. The next day they go to class and all of them made their best attempt, but no one could complete it. The problem? The professor accidentally used the wrong metric on one of the numbers meaning that they couldn't do the steps to what should have been an…

That professor probably had produced the answer already, using the metric he had initially intended. Having a set of answers doesn't mean you didn't make a mistake in the questions.

But it does clue you into whether the professor used a different set of assumptions than you did.
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