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Algorithms, by Jeff Erickson

jeffe.cs.illinois.edu

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Re: Algorithms, by Jeff Erickson

#151

Post by commandlinefan »

_underflow_ wrote: post #3

> Please do not ask me for solutions to the exercises. Even if you are [an] instructor, I will say no. That's kind of a bummer. I like to be able to check my answers when teaching myself things. Am I somehow alone in that?

> I like to be able to check my answers when teaching myself things.

I agree, although looking at the exercises in this book, they seem to be of the form where the only way to give you the answer is you give you the full solution, and they appear to be phrased in a way that makes it easy enough to verify the answer yourself once you’ve figured out the problem. I always feel like the ideal (for me at least) are problems with numerical answers listed in the back of the book – then I can check my answer with the book’s answer; if I got 42 but they got 5, I know I made a mistake somewhere but it’s still up to me to go back through and figure out where the mistake was. It seems like most of these problems don’t lend themselves to short numerical answers like that.

Re: Algorithms, by Jeff Erickson

#152

Post by [deleted] »

thfuran wrote: post #141
dunham wrote: post #129

Earlier quoted context omitted.

I had a math prof who would give negative marks on proofs, preferring you say “I don’t know how to do this step” and finishing the proof over trying to BS the step.

How do you skip a step in a proof? You just say "assuming I can prove this assertion, this other stuff follows"? That seems to risk accidentally skipping way more steps than you thought you were skipping and quite probably the meat of the proof.

[deleted]

Re: Algorithms, by Jeff Erickson

#153

Post by mcguire »

emidln wrote: post #120
Eridrus wrote: post #111

Earlier quoted context omitted.

This is functionally equivalent to being given negative marks for getting answers wrong, which I've seen on multiple choice tests.

Only if no partial credit is offered, which is not how his exam[0] reads to me: As usual, answering any (sub)problem with “I don’t know” (and nothing else) is worth 25% partial credit. Yes, even for problem 1. Correct, complete, but suboptimal solutions are always worth more than 25%. A blank answer is not the same as “I don’t know” [0] http://jeffe.cs.illinois.edu/teaching/algorithms/hwex/s18/fi...

I wonder how much credit the "this is the work of Satan" answers got?

Re: Algorithms, by Jeff Erickson

#154

Post by laurentl »

dunham wrote: post #129
emidln wrote: post #120

Earlier quoted context omitted.

Only if no partial credit is offered, which is not how his exam[0] reads to me: As usual, answering any (sub)problem with “I don’t know” (and nothing else) is worth 25% partial credit. Yes, even for problem 1. Correct, complete, but suboptimal solutions are always worth more than 25%. A blank answer is not the same as “I don’t know” [0] http://jeffe.cs.illinois.edu/teaching/algorithms/hwex/s18/fi...

I had a math prof who would give negative marks on proofs, preferring you say “I don’t know how to do this step” and finishing the proof over trying to BS the step.

A math prof of mine would label insufficient initialization in recursive proofs with i.i. (it also stood for a few other common mistakes, such as “incorrect integration” or whatever). And he would invariably add “i.i = -1”, which was the penalty for such mistakes (exams being graded out of 20). A deliciously nerdy joke, unless you’re on the receiving end.

Re: Algorithms, by Jeff Erickson

#155

Post by kaap »

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…

He was my algorithms professor in ~1999, and he garnered identical praise from our cohort, too.

His approach to demystifying recursion is perfect (Chap 1.2): "The Recursion Fairy will solve all the simpler subproblems for you, using Methods That Are None Of Your Business So Butt Out"

Thanks for your teaching and for this project, Jeff!

Re: Algorithms, by Jeff Erickson

#156

Post by [deleted] »

jefferickson wrote: post #86
_underflow_ wrote: post #3

> Please do not ask me for solutions to the exercises. Even if you are [an] instructor, I will say no. That's kind of a bummer. I like to be able to check my answers when teaching myself things. Am I somehow alone in that?

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…

[deleted]

Re: Algorithms, by Jeff Erickson

#157

Post by laurentl »

jefferickson wrote: post #86
_underflow_ wrote: post #3

> Please do not ask me for solutions to the exercises. Even if you are [an] instructor, I will say no. That's kind of a bummer. I like to be able to check my answers when teaching myself things. Am I somehow alone in that?

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…

For what it’s worth, I find that the answers to the problems in tAoCP are almost always a good balance between explaining the steps to get to the solution and leaving enough out that the reader still has to work to understand how the proof works. But that’s not applicable to all types of exercices.

Your proposed solution (include solutions for a few problems) is definitely a good approach: enough to help the self-learners along while forcing the students to work—I assume you’ll be assigning the unsolved problems in class :)

Re: Algorithms, by Jeff Erickson

#158

Post by specialist »

jefferickson wrote: post #86
_underflow_ wrote: post #3

> Please do not ask me for solutions to the exercises. Even if you are [an] instructor, I will say no. That's kind of a bummer. I like to be able to check my answers when teaching myself things. Am I somehow alone in that?

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…

Idea from common job interviewing process:

Make the unit tests public. Or useable interactively online.

I know it'd be a lot more work. If you had a repo for unit tests, I'd contribute.

Re: Algorithms, by Jeff Erickson

#159

Post by aklemm »

aklemm wrote: post #130
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…

You could consider providing answers and feedback in a premium priced forum or email subscription.

It would increase the odds that anyone getting the solutions is using them to enhance their learning experience rather than as a crutch.

Re: Algorithms, by Jeff Erickson

#160

Post by specialist »

kemiller2002 wrote: post #62
thrwthrw93223 wrote: post #34

Earlier quoted context omitted.

Don’t rob the self-learner that doesn’t have access to TAs, fellow students, and professors the ability to check their work, just because someone else doesn’t have the discipline to not abuse it. Textbook solutions are good for those that aren’t in school, aren’t in formal programs and have no other way of receiving feedback. The “you should know if you’re right” mentality doesn’t necessarily fit a person that’s been…

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…

There's a story of a prof injecting one error into every test.

I had a industrial engineering teacher that did something similar. Every team had a (fake money) budget for each project and bought materials from him (sole source). He'd randomly cut corners, to keep everyone on their toes. Good lesson for the real world.

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