Messages

As of 45 mins before the review lecture, I have received no requests. I will poll you at the beginning of the session, and then I plan to go on with

• some general considerations: what you are "allowed to know"  etc., no need to quote question, no need to cite book pages ... example at the end.
• spring 2018 problem 1,
  • then say something about "other common question types for this topic",
• spring 2018 problem 2
  • ... ditto
• on until the problem set is done
• a few words about other bits and pieces: change of base (recall TP!), homogeneity/homotheticity, higher order appr's, elasticity of substitution, 

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So above I said "example at the end". Here is one: You MUST check whether you are allowed to use l'Hôpital before you apply it. On the other hand, you need not show that a function like ln(x(1-x)) is continuous...

It's about time that the schedule is final :-)

• Taylor won't take all Wednesday, so the rest of the time will be spent on reviewing integration and differential eq.'s.
• A review lecture is announced for Tuesday 27th at 1200.  Three hours allocated just to be sure we don't get thrown out. That lecture will start on the spring 2018 exam ...
• ... and luckily one of you has already helped debug the solution. If there is no "typewriter-font" notification of bugfix on page 1 in your solution document, please reload.
• Nils will not be available next week. Conference, has promised to present something involving a nasty partial differential equation system, and is busy tearing the hair off his head.
  _{(Yeah, the trouble is the limiting behaviour at zero extraction, how could you guess?)}

Nils

A note is uploaded, I put it under "seminar" material because that is where all other solutions are.

It is sketchy; it was originally written as guidelines to the graders, and then I filled in some bits before I uploaded it. As the first couple of lines say, an exam paper should not look like this.

You are probably wondering how it relates to what you could expect on an exam, so let me give a few comments: 

1. (a) Putting up a trap that invites you to taking logs of negative numbers is a bit nasty, and better suited for a "check before using l'Hôpital!" heads-up problem than for an exam. But questions like the first - a limit where you get 0*0=0, just to see if people check that - have been given. 
   Also, both signs of a real constant: again, many papers make assumptions that are not in the problem. Read the problem!
   (b) AFAIK, a problem like this - with x-dependent base number - has not be...

So lectures are on schedule, and the previously announced seminar assignment does not need any changes.

And, the TP review will be on Friday - but note, we had to change the room! The schedule is updated.

Check Canvas: you should be able to see by now.

If you need to get explained a topic and a half, then both Tuomas (room 1143) and Nils (room 1243) are here today - or by appointment. We are not that scary.

So the graders and the administration managed to get this out before close of business, rather than Monday. (We kept the resubmission deadline as it would have been if we had to wait until Monday morning though.)

For resubmission, you should resubmit a complete paper including any parts that were already good (and you may of course copy those from the first version.) Although it is suggested to write by hand, there is nothing wrong about copying a typeset part from your first and supplementing with a handwritten part.

One more thing: for a couple of approved papers, you might need to reload to get the complete feedback. (No verdict changed, do not worry!)

We had a look at it, and you should be able to do the problem set as announced. 

Also, I got a few questions on when you get your TP results ... nothing can be promised, but it looks like it could be at the beginning of next week.

A few updates:

• Tuesday lectures moved to ES Aud 7 (same room as Wednesdays), time unchanged. Effective the upcoming Tuesday 23rd.
  (We just found out that the lecture series that occupied it, is done, so we grabbed the opportunity to move home. Say goodbye to Store Fysiske and hello to the same docucam as Wednesdays.)
• Draft schedule for the rest of the semester posted: lecture topics and problem assignments all updated.
  Unfortunately, the publishing system still has its shenanigans: it inserts "undefined" between paragraphs. I cannot delete it, as it is not in the HTML source sent to the system.
  "Draft" means that there could be changes still.

We have to make some changes to the schedule:

• Tomorrow's workshop is relocated to P.A. Munch's hus. This change is already made in the schedule.
• Next week's workshop is moved to Friday - same hours and room as tomorrow. Change already implemented in the schedule.
  The reason for this change is that with only three seminars left, we need that problem set to include some integrals. We are aware that this is close to the seminar, but I found this to be the lesser of two evils.
• The Tue 13th workshop: now changed from "probably nothing" to term paper review. (There is a need for that.) It might be possible to do it slightly earlier, if you have strong opinions. 
• We have to reshuffle some details in the lecture schedule, but - because the system messed up last time we tried to do things to the "lectures" section - that will not be done until tomorrow....

Remember the TP deadline!

• As mentioned: write by hand! If you cannot scan any other way, use your cell phone camera - but too high picture resolution -> upload trouble.  And, please combine all to a single PDF.

No workshop today - moved to Friday!

• And just to confirm: seminar problems are as announced.
  (If you think #38 is a bit loose worded, I kind of agree.)

Uploads for this week updated (same URLs as before)

• Differentiation in eq. systems will take (quite) a bit of tomorrow. Relevant: updates from slides 14 on in "today's" document. (Hopefully reasonably bug-free, but slide 17 is not the most beautiful that mathematics has to offer.)
• Other updates: bugfix p5, footnote on language p7, and I typed in today's example on p12-13.
• "Tomorrow's" slides also updated. Luckily: less material!

Tuesday: review part on screen. Cookbook on screen. Keep cookbook on screen and give examples on the board. Might supplement this with handwritten examples afterwards.

https://www.uio.no/studier/emner/sv/oekonomi/ECON4120/h18/lecturenotes/econ4120LecDifferentialsEqSystems-preview.pdf

Draft for Wednesday uploaded as well: 
https://www.uio.no/studier/emner/sv/oekonomi/ECON4120/h18/lecturenotes/econ4120LecElastSubst-preview.pdf

... yes, reuploaded 19:28, so if you managed to get it before that: please reload.

There are some changes to relative to the Wed@1AM version, and the first of them will be elaborated after the list:

• The "find an expression for" clarification on slide 18 likely asks for too much in certain cases (though not the example given that page). Good news: "less to do". Bad news: further clarification needed.
  See brief explanation given below - and examples next week.
• New: 31 and 32 have calculations from Wednesday's class
• Bugfixes: fixed numbers in last line p30, misleading wording about what the cofactor is (last line p27), added the word "inverses" in 2nd bullet item p22 due to question in class. 
• Slides 9, 16, 23, 24 now clearer about what was less stressed in class. (That reflects priority.)
• Some Tue-to-Wed changes no longer indicated. Some of the above-...

Rather than a separate file for Wednesday, I updated the "lecture 5" slideset:

• Same link, just overwritten; please reload.
  Expected to be updated after tomorrow with scans. It is Aud7, so I can write and use the docucam.
• Updates and bugfix in "Tuesday's" part largely indicated in magenta colour. Might be removed in the final version.
• New slides "early" in the document: 5 and 7 (example variations etc. mentioned in class). 
  New slides "with Tuesday material" later too, but I'll point that out in lecture.
• There might be (#¤%&stupid) bugs here too, of course - especially considering the time of "day" I post this, but for it to work as "preview" you need to have it by Wednesday morning. 
• Wednesday will start where we left off Tuesday: the inverse. Slides 14 & 15 repeated, with a brief walkthrough slide 16 (which is rather a "see if you can follow this by yourselves afterwards" thing). Then a few things I h...

Uploaded: the draft revised into full slideset for tomorrow - and most of Wednesday, I guess.  Same URL. If you reload, you should get a version which on slide 1 starts with "Have" and has a "To follow today: More of everything", and then a  "Question for you: anything you need reviewed on Wednesday?"
- please form an opinion on that question!  ("Nothing" is a valid opinion.)

Problems for next week: as posted, actually! Just take note: 

• It is the entire 139, but with part (b) done by a different method (given in today's upload, but might not be lectured until tomorrow). 
• 34 is indicated as "possibly low priority"; it does not take long time if you spot it.  But if you don't ... 

• Someone pointed out what information you could get out of the multiple choice thing, so I tweaked it. And I had second thoughts about one of the questions, so ... 
• A few of this week's messages point to dead links because revisions are published under different filenames. I will remove some obsolete messages.

Thanks for the [very sparse!] feedback. Again, you find Olav's e-mail address atop the Lectures section in Canvas.

• I revised slideset 3 to reflect what was covered (though, I kept the "leftovers" in set 3 rather than moving to 4), and I went through the bugfix galore for set 4. Hope I caught all. 
• I will give more determinant examples. However, if there is anything that you need reviewed (for example if the errors got too much in the way of understanding), then I think I have time for that; please forward to Olav by Friday afternoon.
  (Again, I need to prepare on Sunday for you to have it on Monday.)
• Some of you seem to like multiple choice, so I published one. This is my babysteps in Canvas ("why can't the Save and Update buttons do what I think Save and Update should do?!?") so beware errors of all and any kind, and please notify me.
  At least one of the questions contains a trap I would not give on an exam (I hope the comment to the answers reveal what you might not have thought of). 

Seminar problems:

• The first bullet item: " take a stand on whether you by the" Wednesday 3rd lecture. (As mentioned, making updates to the schedule is a risk, and that particular detail is not worth it. But next week I might have to ...)
• Problem 37 has a question on the inverse, that requires tomorrow's lecture.
• Problem 139 (b): it will hopefully be clearer after tomorrow's lecture why this is the thing to do, but solving the equation system by Gaussian elimination should be doable by now.

(Before) tomorrow's lecture:

• I'd appreciate if you could browse the first four problems in the most recent set in Canvas, to see if "it makes sense".
• We will do:
  • more Gaussian elimination examples (I doubt if that long problem 2 will be covered though),
  • then say a little bit about the inverse as a concept; one...

Uploaded: 

• "Prettified" notes from today uploaded.  
• Also a new set of "more fundamental" problems.  
  (Yes it is easy to make mistakes on these too!  They are "fundamental" in the sense that you might go very wrong if you don't get this right from the beginning.)

Consultation hours: 

• Mondays from 1415, updated here.

Contact student appointed:

• Olav Abrahamsen.  For his e-mail, see Canvas, first headline under "Lectures". 
• I intend to consult him often.  Please forward any reactions to him while I can still adjust, I only have six lectures left.
• In particular, on notes/slides: 
  • Does the format of preview notes/slides/write on slides/upload afterwards work with you?  
  • Please forward...

• Three pages scanned notes that I used for today
• "preview" of tomorrow. With space to fill in calculations.
  • Question: Aud 7 has docucam for handwriting; Should I write on those notes, or not?
    Pro: you get the order of events;
    Contra: they might not fit what notes you want to take.
    Form an opinion, please.

And tomorrow, I want a contact student. Or two.

As mentioned in class, we dare not touch that schedule thing (yet), so it does not give the correct teachers; I (Nils) will give linear algebra, and you find me at "ncf" at econ dot uio dot no and room 1243 (just next to the Dept front desk). Consultation hours will be discussed with you, and I will want a contact student.

I have put out a "preview note" for the beginning of the linear algebra section (also linked to in Canvas; edit: re-upload Sunday morning). The first linear algebra lecture will have a lot of talk about the basics, and Ola has already covered quite a bit of it; so, I will progress fast until the end of that note. Part of the idea with the note is that you can have a peek at what this is about, and decide...

In today's lecture I spotted a mistake in my notes on the "more technical take on the Envelope Theorem in Kuhn Tucker problems". The mistake undermined the proof I was going through so I told everyone to abandon it and wait for further message. 

I have now reviewed my notes and confirmed that it is wrong. However the correct proof is not that relevant for what we have been studying in this course, so you can all forget about it. Let's just stick to the simpler interpretation that was covered in the lecture. 

You Ola Wu

About the workshop format:
The idea is a working environment for you to start on next week's problems, discuss and ask questions. It is not supposed to be a quiet zone. Form groups if you like. Later you could as well review previous seminar problems that you need to have explained.
(The arrangement resembles the seminar format at UiBergen's "Math 2".)

About the problem set for seminar 1:
One problem requires theory not covered until tomorrow. (Maybe we should have put that up as an extra question: which problem is not yet possible?) It is 2004#1d. There is plenty else to start on today.

Canvas and where to find information:
We acknowledge that you shouldn't have to look in several information channels to get updates. Here is what we will do:

• The sch...

For now you can access them at:

http://folk.uio.no/ncf/4120_oldexams/

... likely there will be a delay the upcoming week (l'Hôpital's rule can take more time). Ola decides the progress.
Due to the technical issues, I dare not change anything in the lectures section until I absolutely have to. 

Also, we want to know: does everyone get Messages into their feed? (I.e., as a notification without actually having to look up the course web site?)
Ola will ask you tomorrow whether you got this one.

Nils