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Gruppwebben som samarbetsyta stängs 31 december 2026. Du som administratör behöver nu exportera gruppens innehåll och/eller radera gruppen.

Observera: Från och med den 1 oktober 2026 kommer delar av gruppwebben som inte längre används, successivt att stängas ned, exempelvis gruppwebbar som redan har flyttats eller varit inaktiva under en längre tid.

Mer information hittar du i nyheten: Gruppwebben och Social stänger hösten 2026. Stöd och instruktioner för hur du exporterar en gruppwebb finns i: Gruppwebben som samarbetsyta stängs hösten 2026.

Deadlines

Dates for Homeworks, Presentations and Oral Exams

  • Monday, March 6, 23:59 Group project part I:
    • Email PDF to dog@kth.se
    • Use topic "DD2448 Group Project".
  • Monday, April 3, 23:59 Group project part I:
    • Email PDF to dog@kth.se
    • Use topic "DD2448 Group Project II".
  • Monday April 19, 23:59 Homework I.
  • Group project part III and IV Sunday 23.59, May 14.
  • Monday May 29, 16:00 Homework II. You can submit by email as explained in the news feed.

Douglas Wikström skapade sidan 1 november 2016

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kommenterade 19 januari 2017

When will this page be updated? Is it possible to get the deadlines far in advance so we can start planning early? I suspect a lot of us have a lot to do, and would prefer doing things early instead of the day before it's due.

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kommenterade 23 januari 2017

It was asked during the last lecture and the answer was that the deadlines are not set yet, and won't be for a while. As for a rough estimate it was mentioned that the first homework probably won't be out for at least a few more weeks since we need to cover more of the course.

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kommenterade 27 januari 2017

Even though the deadline isn't set and there's more to cover in the lectures, it would be nice if the actual homework could released.

It gives us a better idea of the workload to expect and allows people with tighter schedules to start early and maybe read ahead (since all the lecture slides are already out).

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kommenterade 25 februari 2017

In case someone was not present during last Friday's (2017-02-24) lecture, a deadline was set for the preliminary part of the group project. By Monday 2017-03-06 23:59 CET, each group should send via e-mail to the course responsible of short paper (4/5 pages) studying and comparing the characteristics of an handful of authentication methodologies. The e-mail subject must be 'DD2448 GROUP PROJECT' and the document should contain names and e-mail addresses of the group members. Moreover, the use of LaTeX for the compilation of said document was strongly suggested.

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kommenterade 28 februari 2017

Hello,

My group and I had a couple questions concerning the project (unfortunately none of us could attend last friday's lecture). Are the authentication methodologies techniques such as biometric authentication/two factor? Or must we present low level implementation such as sha256, etc..?

Best regards,

Christophe

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kommenterade 28 februari 2017

@Christophe

What he said in class was to not go into too much detail and instead focus on "flow of information". Examples of things you could research were Swedish BankID or the Estonian ID-card. So from that information I understand it as more "high level" stuff, I even think someone briefly mentioned biometrics in class and he seemed to agree that it was a good thing to research. 

But the fact that today is Tuesday(less than a week until the deadline) and we still don't have clear instructions posted online is ridiculous. Instead we are relying on second hand information from other students who were present at the lectures. I also think we could have gotta bit more of a heads up of when the deadline would approximately be, so that we could have more time to form groups(mine still has a vacant spot hmu if you want to join). Nothing to specific, but a little note of "you should find groups now" the week before would have been nice. 

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kommenterade 1 mars 2017

I think we should push on moving the deadline forward as it was a very short notice especially in the end of the period where some of us have tests very soon ( I for example have one the same Monday the HW is due)  and when all the final projects and HWs are due .

What do you think?

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kommenterade 1 mars 2017

@Mati I don't want to speak for Douglas but I don't think he will agree to that. He said he wanted to put some pressure on us and he also discussed the deadline with the people at the lecture. Which means he did not decide on it all by himself. There is always someone who has something else at the same time so I think it will be impossible for him to please everyone.

And I believe he is away on vacation/something this week so who knows if he will see these comments in time.

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kommenterade 1 mars 2017

Even though I attended last weeks lecture, I still feel like there is a huge information gap between the students and the teacher. We were told to do a research regarding securtiy implementations and to write 4-5ish pages. No info on what scope to use or further instructions were given. Douglas also said that the next lesson will be cancelled and that he would post this info asap. I wonder how many people will show up on friday just because of the lack of information from Douglas' side.

What is going on?

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kommenterade 1 mars 2017

"Wanting to put some pressure on us" is kind of a bullshit reason to give us a one-week assignment on a quarter-speed course, right before exam season. Surely any other time would have been better? Not to mention the imprecise instructions and still having no official announcement beyond mentioning it on a lecture that any number of people could have missed. It's not even posted on the deadlines page yet, and it's supposed to be due in less than a week? What's going on here?

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Lärare kommenterade 1 mars 2017

I think you are a bit off target here.

  1. It has been clearly stated that you are responsible for keeping track of what goes on at lectures, and also how we agree on deadlines. Homepage is for informational purposes and I try to keep it updated.
  2. The deadline was discussed and agreed on during the lecture. There was ample opportunity to change it, but we need to do this sometime during the course.
  3. The lack of information is intentional. A written description would not contain more than what was stated during the lecture. I am fully aware in what way this is hard. Why is it important with open-ended problems?
    • It is fun for students that wants to learn and gives them choice.
    • It forces you to think about what is important and use your own judgement.
  4. There is something for everybody in the course. There will be no lack of information in the homeworks and there is both theory and implementation problems.
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kommenterade 1 mars 2017

While I understand that we're responsible for keeping up with any lectures we miss, I hope you understand that this becomes hard when very important information like this (the existence of a deliverable) is _only_ mentioned on the lecture. 

When you say that we're responsible for keeping track of what goes on at lectures, does that mean that we're responsible for never missing a lecture? If Matteo hadn't informed us, we never would have known.

To be clear, I think for most people here the problem is not the small amount of information or the deadline, but rather the lack of _official_ information. If you had updated this page with the deadline and one sentence about it such as "Write 4-5 pages on the characteristics of a handful of authentication methodologies such as Swedish BankID", I think there would have been less confusion about this. 

Finally, since this is "group project part I", what part is this for? Looking at the slides from the first lecture, there's 4 parts (worth 20p each). The first part there is "Describe and provide a security analysis of a way to authenticate a voter in an Internet voting system". Does this mean that we should focus our research around authentication methodologies for internet voting systems?

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kommenterade 1 mars 2017

Thanks for responding and updating the page.

I feel the need to respond to one of your statements here though.

> It has been clearly stated that you are responsible for keeping track of what goes on at lectures, and also how we agree on deadlines.

Sometimes, people miss lectures. Every lecture will have some people missing. Most or all people will miss some lectures. It would be very inefficient to after every lecture have someone ask "What did I miss today? Was something extremely important announced today?" Students here are very familiar with the fact that you need to "catch up" in private study whenever you do miss a lecture. But deadlines need to be announced in a somewhat timely manner, in a centralised location, and with at least as much instruction as is necessary to complete the task. (The retellings in this thread are sufficient, since you say the open-endedness is intentional.) Because some people will have missed the lecture, and not everyone has some friend or study partner in the course (or else their friend might have missed the same lecture).

Imagine if Matteo had not felt the need to post this initial message, and you only announced this now. People would have had less than 3 work days to complete this assignment. That is, in my opinion, woefully insufficient. I understand and wholeheartedly agree that people need to keep up with the lectures if they miss them, but that only goes so far. It's not reasonable to expect everyone to know about a deadline that's been announced only once, on a lecture, on such short notice. The only way you could reasonably expect this is if you assign people - presumably TAs - to spread the word on important deadlines, and at that point you still have to reliably deliver the information to those parties so it's no more work than putting it directly on the website.

Please, if nothing else, at least consider asking those present at the lecture to get word out on Social as soon as possible, and follow up with official instructions at your earliest convenience. Second-hand information often misses important details and can be completely inaccurate.

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Lärare kommenterade 1 mars 2017

We can discuss this in class.

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kommenterade 2 mars 2017

Just to be sure, tomorrow there is no lecture ,right?

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kommenterade 2 mars 2017

So with class you mean the 24th? Almost three weeks after the deadline?

People only want a short description of what we are supposed to do in text written by you so that we don't do the wrong thing. The text can be very open but people want it in text.

I agree with deadlines being only announced in is sub-optimal but honestly he has said that he expect us to keep track of what happens in class so that isn't the problem here. You don't have to agree with it but keep focus on what's actually important.

Also, "only four workdays", if you are a group of four people writing 4-5 pages should take at most a day.

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Lärare kommenterade 3 mars 2017

Correct. No lecture Tomorrow/Today Friday March 3.

We can discuss next lecture.

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Douglas Wikström redigerade 24 mars 2017

Dates for Homeworks, Presentations and Oral Exams
* Monday, March 6, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project".

* Group project part II. To be negotiated during lectureMonday, April 3, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project II".

* Monday April 17, 23:59 Homework I (handed out Monday, March 24.7)

kommenterade 29 mars 2017

Where can Homework I be found? said it would be out 2 days ago, yet I cannot find it.

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kommenterade 29 mars 2017

The homework should appear under 'Handouts', but it's not uploaded yet.

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kommenterade 29 mars 2017

That's what I suspected.

If this is the case, I would argue for a renegotiation of the deadline in proportion to this delay.

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kommenterade 29 mars 2017

We still have more than two weeks left, even those who have exams during easter should still be fine since they were give the weekend after.

However, should it not be released today or early tomorrow I agree that it should be changed.

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kommenterade 29 mars 2017

Could someone (Douglas?) please elaborate a little bit regarding the requirements for part II of the group project? I remember it being said that the report is expected to contain math, but it's pretty unclear to what extent and how formal it needs to be. How many pages (roughly) are expected?

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kommenterade 29 mars 2017

@petercap We are to have a mathematical rather than programmatic viewpoint when writing. That is, any formal proofs or similar arguments should be expressed in math or propositional logic, and if you find yourself writing source code or pseudocode in the report you're probably doing it wrong.

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kommenterade 3 april 2017

https://kth.kattis.com/problems/oldkattis.aes

Is it possible to read the input properly on windows? I write in C++. I tried using scanf as unsigned character and fgets as string but both do not work properly.

What is the right way to input and output for this problem?

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kommenterade 10 april 2017

@Chun

Can't help you with Windows, but the program should be exactly the same, you should only need to change how you run it. I tried a few different ways, the biggest problem is reading until EOF.

I ended up doing:
cont = static_cast<bool>(cin.get(c))

cin is std::cin and the static cast is there is needed to store the return value in a bool variable. It will be false if you reach EOF.

I think others found cleaner solutions though.

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kommenterade 13 april 2017

@Robert

Thank you for your help. I'm using Ubuntu now and your input function works there. Now I'm stuck with the output. I store each output byte as an integer. The values are correct in the hex format, but even I tried casting the values as char or unsigned char and using printf("%c"), it produces some weird output. How can I output properly?

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kommenterade 13 april 2017

The AES assignment uses binary input and output. To correctly handle IO, if you use a POSIX compliant OS (i.e. Linux) I suggest you to take a look at the read and write syscalls (the standard file descriptors for stdin and stdout are 0 and 1 respectively), if you want to be more general you can check out fread and fwrite (global IO file pointers are defined in stdio.h).

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kommenterade 13 april 2017

@Matteo

It seems I have fixed the IO issues. Thank you.

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kommenterade 15 april 2017

Anyone else getting Memory Limit Exceeded on one of the later test cases, using Java? I/O seems to be working fine, considering I pass the first four test cases. 

I don't have any idea what could be causing this since nothing should be retained between the blocks. I'm doing most of the calculations in-place and each block is 16 bytes, so the space should be around the same for each block.

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kommenterade 15 april 2017

The last case is MUCH larger than any of the other ones so you are probably simply leaking memory. It might either be because of you storing references to old value in a data structure (directly or indirectly) or you are recursing and allocate a matrix for every recursion.

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kommenterade 15 april 2017

I'm getting the MLE on the fifth test case. If I add a System.gc() call between each block, I get all the way to the 7th test case until I get a TLE (probably due to the massive amounts of gc calls.

I don't have any recursion, I've spent hours looking for a old references being kept around. Since I don't have any global/static/instance variables, and it's all local, as soon as I exit out of an AES-call for a block, the previous references should be gone.

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kommenterade 15 april 2017

Java will only put the references on the stack, the referenced objects are allocated on the heap. So even if a method exits, it's referenced objects will remain in the heap until cleared by the garbage collector. The garbage collector probably doesn't bother running by itself often enough or even at all. Consider reusing the same block buffer for every encryption.

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kommenterade 16 april 2017

Was the deadline for Homework I moved? It says Monday April 19, but monday is on the 17th. I have a vague memory if it being moved but now I'm uncertain.

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kommenterade 16 april 2017

It was moved from Monday April 17th to Wednesday April 19th. He just forgot to edit the name of the day.

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kommenterade 17 april 2017

Note that the CSC service desk closes and locks the door at 16:00, so handing in the homework in the krypto17 compartment is not possible after that time.

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kommenterade 17 april 2017

> The printed sheets of paper must not be stapled together, collected with a paper clip or similar. Instead they must be collected into a transparent folder with easy access.

Are transparent folders available in the reception for easy turn in? Such folders can easily become expensive quickly unless you get them from the right place, and I don't believe requiring students to purchase accessories to be able to hand in mandatory homework is entirely along the lines of school policy.

Alternatively, do you know of a good place easily accessible from campus where transparent folders are sold cheaply or in bulk? I could pick up a pack for my personal use, take enough for the rest of the course for myself, and volunteer the rest at the service desk a few hours before the deadline, for the benefit of those who can't afford or don't want to spend the energy buying it themselves.

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kommenterade 17 april 2017

Though I agree that having to buy accessories in order to submit mandatory homework is not 100% correct, I got 2 plastic covers at Nymble's stationery shop for 6:- . I'm pretty sure anyone can afford that.

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kommenterade 17 april 2017

Is it ok to email the homework since the deadline is 23:59?

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kommenterade 17 april 2017

No, the instructions clearly say "No other way to submit solutions is allowed".

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kommenterade 17 april 2017

Then why have a deadline at 23:59 ?

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kommenterade 17 april 2017

Good question, it was probably just an oversight by the professor. Or, it is a way to test the ability of the students in picking locks / tampering smart-cards.

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kommenterade 18 april 2017

I went to the CSC student office to submit the homework but there was no "kripto17" folder, just a generic folder labelled "DD2448" full of assignment submissions from last year. The ladies at the help desk could not give me any explanation, so I put my papers in there anyway hoping they won't get lost. Does anyone have a bit more info about that?

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Douglas Wikström redigerade 19 april 2017

Dates for Homeworks, Presentations and Oral Exams
* Monday, March 6, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project".

* Monday, April 3, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project II".

* Monday April 19, 23:59 Homework I (handed out Monday, March 29)
* Group project part III and IV TO BE DISCUSSED IN CLASS.

kommenterade 21 april 2017

Hi! I won't be able to make it to class today. To both Douglas and classmates, please try to keep notes and post what decisions and important clarifications are made verbally.

For the deadline question, please keep in mind that we've just had a hard push for the latest homework. If we schedule project 3 and 4 so soon that we need to spend more than a quarter-speed class should have time for... well, just please don't. Leave a little room in there for us to have pushes for other courses.

Thanks in advance

Sean

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kommenterade 22 april 2017

@sean

I doubt that will be very possible. We will need at least two weeks for HW2 and there are only 4 weeks of school left. If the deadline is set very late it will need to overlap with the Homework. So regardless you will need to finish it quite soon.

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kommenterade 22 april 2017

That's a fair point. I'd argue that if we're forced to spend overtime on a given course over an extended amount of time, something has gone seriously wrong with the planning and/or execution of that course, but that's to bring up with the teacher or student council after the fact, not in this forum and format.

Still interested to hear what was actually said at the lecture, since group project part 3 and 4 were going to be discussed yesterday. Were any important deadlines set or clarifications made?

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kommenterade 23 april 2017

@Sean

AFAIK no real deadline was set since Douglas sort of forgot about it until everyone was just about to leave, so it was only talked about very swiftly. The way I understood it was that the deadline for project part 3+4 isn't going to be very soon. I'm guessing it will be discussed during the next lecture. But in my opinion, slowly starting to work on the project right away is proably the safest bet.

And about the planning stuff, the course is suppose to be 3 HP in period 3 and 4,5 HP in period 4. But let's be real here, we only had a few lectures and project part 1 in period 3 and we have lectures + 2 homeworks + 3 group project parts in period 4. I don't know if that equates to a 3/4,5 HP split

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kommenterade 23 april 2017

Keep in mind that you are supposed to be studying on your own throughout the course. If you started studying the theory when the homework was assigned you only have yourself to blame.

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kommenterade 23 april 2017

Thanks Nedo for the information.

I'm still quite frustrated though that Douglas keeps ignoring our emails and the comments here on social as well, especially close to a deadline. I know that he has a lot to do with the course but this really makes it hard for us students to know what to do. I still don't know if the first project parts was sufficient since no grades has been reported and the emails regarding this has been ignored and at last lecture we basically got told the he had been getting so much emails he couldn't respond to them. 

There is also that the day of the turn in of the report with the theory questions there was a bunch of questions regarding for example how to solve the problem with the CSC closing at 16:00 when deadline was at 23:59 which was no where stated more than from comments from other students.

Not to mention the lack of planning mentioned above with putting all the work basically in period 4 and putting a 2 week deadline over an re-exam period + Easter. 

I know I'm a bit late to the party with this comment but I was naive and thought this would get fixed as the course continued but instead became worse. 

Hope this gave some food for thought and if nothing else inspire Douglas to make the course better for next years students.

Kind regards
Mattias Larsson

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kommenterade 23 april 2017

@Robert How would you prepare when topics such as elliptic curve were only covered on the last lecture, which was AFTER the submitted homework 1? Were you expecting these assignment to be on the homework when we haven't touched the area during the lectures ? I thought the point of postponing the release of the homework was that we needed to cover everything in class before.

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kommenterade 24 april 2017

@Mattias it was a 3 week deadline, I asked to have it extended to cover the re-exam period since a lot of people didn't have exams then. Also, most questions asked was either answered by the other students or was about people needing help to debug their code. Regarding the reception the solution was to hand it in earlier, a few hours won't matter for a 3 week deadline. Douglas did respond to the important kattis-GMP problem and the correction for 6c.

@Marcus, I read the lecture slides and I read a large part of the book. I also skimmed through all major topics on youtube and similar. Of course you don't end up knowing everything, but there is a hell of a difference between filling the holes and starting from scratch. I also looked at last years homework to get an idea of what kind of questions might appear. Sure, I might agree that the elliptic curve question should have been put in HW2, I was mostly talking about other questions in general.

Also, keep in mind, you need something like 20 out of 76 to be on a passing grade for HW1.

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kommenterade 4 maj 2017

Are there any news on the deadline for parts III and IV of the project?

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Douglas Wikström redigerade 9 maj 2017

Dates for Homeworks, Presentations and Oral Exams
* Monday, March 6, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project".

* Monday, April 3, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project II".

* Monday April 19, 23:59 Homework I (handed out Monday, March 29)
* Group project part III and IV TO BE DISCUSSED IN CLASSSunday 23.59, May 14.

kommenterade 9 maj 2017

So how will the hand in be done for part III and IV ? Will it be via mail or physical (is the office even open on sundays?). Also what should be included in the hand in? report + feedback + code?

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Douglas Wikström redigerade 11 maj 2017

Dates for Homeworks, Presentations and Oral Exams
* Monday, March 6, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project".

* Monday, April 3, 23:59 Group project part I:
* Email PDF to dog@kth.se
* Use topic "DD2448 Group Project II".

* Monday April 19, 23:59 Homework I (handed out Monday, March 29).
* Group project part III and IV Sunday 23.59, May 14.
* Sunday May 28, 23:59 Homework II.

kommenterade 16 maj 2017

Does HW2 have to be handed in physically at the CSC office like last time? If yes, can we please have the deadline extended by 12 hours so the deadline actually occurs when CSC is open?

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kommenterade 16 maj 2017

It was discussed last time in class and we agreed that the deadline should be moved to Monday May 29th. However, the page was not edited.

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kommenterade 16 maj 2017

What time was decided? 23:59?

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kommenterade 16 maj 2017

@Anton Probably 16:00 since that's when the csc office closes.

@Douglas Can we get some information on the missing points issue? I feel like if questions are going to be added, we need them asap.

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kommenterade 16 maj 2017

Not to mention that we still haven't gotten any results from hw1, kind of hard to know how much you will have to commit to this homework without those results and if the solutions was sufficient in the last one or if one has to be more details and etc.

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kommenterade 26 maj 2017

Hi, what happened to the deadline in the end. Was it moved to Monday or do I have to hand in my written solution today? (Is the student office even open today?)

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kommenterade 26 maj 2017

@Andre Josefsson

The student office is closed today for holiday reasons. The deadline to hand in HW2 is until Monday. 

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kommenterade 26 maj 2017

@Christophe Valahu

Thank you!

Do you know what time the deadline is monday, and also if the implementation problems have monday or sunday as deadline?

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kommenterade 26 maj 2017

I seriously hope it was officially moved to Monday. I tried handing in my solutions, but the CSC office has been closed both yesterday and today and will be also closed for sure in the weekend.

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kommenterade 26 maj 2017

The deadline time is 16:00, since that's when the student office closes. I'm also guessing that the implementation problems have the same deadline on monday. 

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kommenterade 26 maj 2017

I would not assume that the deadline for the implementation part is also extended. I think Douglas said something about this in class but I cannot remember what he said.

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kommenterade 26 maj 2017

Douglas, can you confirm what the deadlines are (both date and time) for both the theory and implementation tasks?

I missed the part of the lecture where you discussed this, so all I have to go by now is ambiguous second-hand information.

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kommenterade 28 maj 2017

I've read through all the comments, but am extremely confused, there's a lot of contradiction. Does HW2 have to be handed in physically and by email, or is just an email sufficient?

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