Survey Responses

Here are results from the Quick Surveys submitted so far (I will leave the survey open, so you can submit at any time).

24 surveys were submitted.

That’s a pretty dismal response rate! The survey was very short and simple to submit, but barely 1/3 of the class did so. Perhaps only people who are unhappy with the class filled in the survey and the majority are perfectly happy with how everything is going. If that’s not the case, its not too late for the rest of you to still submit surveys.

Pace of the Class

Way Too Fast: 1
Too Fast: 8
Just About Right: 12
Too Slow: 3
Way Too Slow: 0

I read this as meaning the pace should stay about the same. I think it is better if the class is challenging to most students rather than being too dull. That said, most of the ideas in this course build on things that are covered in the beginning of the course. So, its important for everyone to understand those main ideas before we go on to more advanced topics. Hence, if you are confused now, it would definitely be a good idea to come to office hours or schedule a meeting to clear things up.


More Applications: 7
More Examples: 17
More History: 0
More Detailed Proofs: 0

I’m a bit surprised by this since I think we’ve been doing a fairly high number of examples already, but I will try and do more examples in future classes. The book, of course, also provides many more examples of the same types of problems we do in class.

I do agree that we’ve been fairly light on applications so far. There are many interesting applications of DFAs, NFAs, and CFGs. We’ll definitely have some time for applications next week. I do want to emphasize, though, that applications are really peripheral to the main concepts in this class.

More Chalk: 4
More Ink: 10
More Prepared Slides: 10

A very mixed response. Unless the late submitters make a strong appeal for chalk, I will mostly avoid using chalk (mainly because being left-handed I find it quite hard to write with chalk without smearing it all over the place). I think ink is fun, but can be distracting (and it looks like about 1/2 of you agree). I’ll keep using a mix of ink and prepared slides, where which works best depends on the type of content.

Open Comments

It would be more fun if students were not as meek and decided to voice opinions more often.

Agreed! I definitely appreciate students speaking up with questions, comments, and objections (especially when I mess something up), not just answering questions I pose directly.

Pretty good so far, sometimes when things get technical with lots of symbols its a little too fast.

Conceptually, I like the course. However, there are 2 things that are bugging me: My homework grade, and the 500 symbols that end up being on the board at 1 time. … And the symbols on the board… With stacks today, just by looking at the diagram drawn out I understood how they were useful and saw that we could possibly get creative to make machines that work a lot like a program. However, then we switched to the symbolic notation and staring at all of that just doesn’t do it for me. I get lost too easily and would rather just learn more different machines.

One of the goals of this course is to improve your ability to reason about formal systems in a fairly formal way. This does involve lots of symbols and symbol manipulation. Mathematical notation provides a compact and precise way to express an idea, and getting used to reading and writing this way is a valuable skill (even if you end up not doing work in theory).

That said, the big ideas and concepts are not about the details of manipulating and understanding lots of symbols (and I’ll be the first to admit that the DPDA model from the last class involved way too many symbols!) I don’t want to lose the main ideas by getting too lost in the symbols. Definitely stop me in class if it seems like the symbols are unclear, or if the main idea isn’t clear before we delve into the more precise formalism.

I feel like things aren’t clearly explained. I sometimes get lost during the proofs (especially the delta ones). More explanation would be appreciated! (Pumping lemma = ???) Also, the readings don’t go along with what we are learning right now. Unless I missed where the reading was posted…

The reading assignment is Sipser Sections 2.1 and 2.2. We’ve covered some things in class that are not in the book, and some things in a different order. Deterministic PDAs are not in the book, but Section 2.2 covers non-deterministic PDAs. Section 2.1 introduces context-free grammars (which we’ll cover in Class 7). I do this in a different order than the Sipser book to make the connections between DFAs and PDAs more clear, and then switch to relating them to grammars.

As for the pumping lemma, I think we’ve spent quite a bit of time in class on this, but I’d be happy to go over it again in office hours. The problems on PS2 should give you a good sense if you understand this well.

I think it would be helpful to provide examples more pertinent to particular homework problems (something like, You might use this approach for number 3 on ps such and such.”)”

Part of the goal of the homework is to get you to think for yourself about how to approach a given problem. Many of the examples we do in class do relate closely to problems on the problem sets, but I want you to think about them and draw the connections yourself. (I’ll make an exception in class today, though.)

There are not enough office hours. I cannot attend the professor’s regularly scheduled office hours nor the TA’s scheduled office hours. I have reservations about bothering the professor for a half hour meeting every week. Is there a way to reschedule the office hours with the TA or to talk about special meetings? It would help immensely.

We’ve tried to schedule the office hours to be accessible to as many students as possible, but unfortunately its not possible to find times that work for everyone. You shouldn’t feel uncomfortable about scheduling meetings not during office hours, though. I’m happy to do this, and we can find a time that works for both of us.

For me at least, I believe the homework should be due later on in the week. I usually start my homework on the weekends, and usually won’t be able to make the office hours on monday. It would be helpful to have the home later on in the week and have more office hours before the homework is due. Addtionally, it would give us the opportunity to ask questions about the homework in class.

The class schedule works best with assignments due on Tuesdays, but if it helps you get started earlier feel free to assume problem sets are due the previous Friday, instead of the Tuesday when they are actually due. For PS1 and PS2, they were assigned on Tuesday or Wednesday and due two weeks later (For PS3, there will only be one week.). So, for PS2, between when it was assigned and due there have been office hours on Thursday, Monday, Thursday, Friday, Monday. I know it may not be possible to make it to all of these, but there were plenty of office hours available during this problem set. In general, my office hours the day before problem sets are due have been somewhat crowded, but other days have not been very busy. So, you’ll definitely get more help if you start assignments early and take advantage of the early office hours.

Have you considered posting the lectures online? I’ve had three other CS professors put the slides and audio associated with them online and these lectures are very useful for working on assignments and studying for exams.

I’m a bit confused by this one, since I always do post the lectures on line. They are on the course website. If you mean audio or video specifically, I understand this could be helpful, but don’t do it for several reasons. The main one is privacy — I want students to feel free to ask questions or make comments in class without worrying about it being recorded. Many people (including myself) act differently when they know they are being recorded, and I definitely wouldn’t want to record people without their knowledge.

When you use tablet and write your note on it, it is great but please upload your ink to the website too. It is really helpful.

Yes, I mean to include the ink in the posted slides. For Class 5, my machine crashed before I was able to save the inked slides, so unfortunately the ink is lost. Sorry about that!

I’d really appreciate it if you could make the lectures more lively and somewhat more entertaining. I’d love to have a few jokes in the middle of class, maybe an unexpected funny picture to keep us all more entertained and focused. Right now, it’s a really dry lecture that seems like everyone (including you, professor) is just dragged through. I’d appreciate any ways of making it more entertaining

Also, this class is supposedly not an attracting class, but you have made it really interesting. Thank you so much. It’s just some time around 2:30-2:45, I will get extremely sleepy and can’t help nodding my head. If you see more than 5 people are doing the same thing, could you pause the class for a little while and ask everybody to get up and do a stretch?

I hear you. I don’t feel like I’m dragging through lectures (other than a few times when I have gotten bogged down in the details of a proof), but sorry if it comes across that way and I do realize that 75 minutes is a long time to sit in lecture, especially in the afternoon. I don’t recall seeing more than a few people sleeping, but some of you may have mastered the skill of sleeping with your eyes open. I’d ask if you do fall asleep in class, to please make sure to snore loudly or flop over in your chair so it is obvious to me that you are asleep!

I don’t think its a good thing to disrupt class with irrelevant humor or gimmiks (and I make no pretense to be a comedian), but I will try to find more ways to incorporate “entertaining” things that are relevant to the core content. This should get easier as we progress through the class.

The homework, I like being simple and just trying to do something useful with the things we’re learning, for instance, building the automata to model how a system should work. The proofs kill me for some reason, they’re just not interesting and I guess I don’t write enough for partial credit.

Learning how to write good proofs is an important goal for this course. Hopefully, the feedback and comments from PS1 will give you a better idea of what we are looking for in the proofs. The goal is for you to write proofs that are clear and convincing to a reasonable reader. What this means, of course, if quite subjective. We don’t want a lot of gory details that aren’t necessary to make your argument convincing, but we also don’t want a proof that skips important steps (which may seem obvious to you, but would not be obvious to others). If the proof seems uninteresting, that is probably a sign that you may be missing the important step (at least, my intent designing the problems is that there is something interesting in a good answer). Please don’t misinterpret the grading as meaning longer is better. The best proofs are short and elegant.

Please feel free to post comments here (or resubmit an anonymous survey) if you think I’m misinterpreting or misunderstanding the survey responses.

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