Okay, good morning guys, Discrete 
Optimization Mail Bag Week Four. 
You won't see me today, I'm going to be 
truly invisible. 
I'm on the West Coast of the United 
States, in Seattle. 
If you would see me, you know, would drop 
the class immediately. 
I'm so exhausted that you'd think I'm 
going to die and not being able to 
deliver any kind of certificate, so don't 
worry if you don't see me, it's just for 
your own sanity. 
But I can't do much not to give you these 
mailbags. 
So announcements, you know the mid course 
survey's finishing in a week. 
So please, you know, fill it in if you 
want to , we'll review the feedback that 
we got in next week's mailbag. 
We have already looked at some of the 
stuff so this, so this is quite 
interesting. 
We also wanted to tell you that we have 
updated the VRP grader. 
We, we were a little bit too tough so we 
lowered the bar for getting ten points 
and this is something that I'll cover a 
little bit more in detail at the end of 
the mailbag. 
posting your experience, so this is, this 
is really nice what has been happening 
and, you know, when you teach the class 
in a regular university so what happens 
is that a lot of the interactions in 
class you know, you, you have students, 
that is happening, and you have students 
talking about what they do. 
Other students asking questions, so the 
way to do this in an online class is to 
go to the forum. 
And so I think a lot of people have 
stepped up, have told, you know, other 
people what they were doing. 
you know, give some you know, insight on 
what works, what doesn't work. 
I think that's great. 
People should keep doing that. 
People should ask questions. 
I think this is very much in the spirit 
of the class, you know. 
And, and once again, I want to repeat 
that you know, the policy, the 
collaboration policy is very lenient. 
You can do a lot on the forum and help 
fellow students or ask help. 
This is a very important part of the 
class. 
this is a, a couple of slides on the 
statistics. 
So this is, these are the students who, 
who are active in the assignments. 
We are still, you know, above a thousand, 
which is, you know, or dream, you know, 
achieving a, you know, a thousand 
certificates. 
So, so this is great. 
Keep, keep working. 
Keep, keep going. 
This, so this is going fine. 
this is the total submission graded. 
Okay, and what is amazing there, you 
know, can you realize we have graded 
100,000 feet, 150,000 assignments at this 
point. 
You see the curve which is graded nicely 
so this is, this is good news. 
The number of submissions per active 
students, it seems that, you know, people 
are basically submitting 20 times if hey 
are active. 
So this is getting, this is stability at 
a very nice point, now. 
That means we have a stable group of 
students there. 
We should keep that at that level and 
this is, this is great. 
on track part per active student, once 
again, nice progression, it's going up, 
it's going up, that's what we want. 
We want things to go up and stay going up 
at the same you know, rate so this is, 
this is, this is good. 
this is an interesting slide. 
Actually this is a participation part of 
the assignment, so there are a couple of 
things interesting here. 
The TSP, we are almost there. 
This, you know, 1,000 mark that we want. 
what is also interesting is that people 
keep that fact and graph covering, there 
are more people acting on these 
assignments. 
And so that means people are still 
joining the class and trying to catch up. 
So this is amazing. 
So that's, that's get us very excited. 
So, you know, you know, welcome all those 
of you who are doing that and hopefully 
everybody is going to basically get this 
bar full of TSP at the, at the 1,000 
soon. 
we did another thing here which is 
basically inside the Grade tab. 
We added a plot just to stimulate 
everyone. 
So what you see in this plot is basically 
on the x-axis the points awarded over, 
you know, the points awarded and, and the 
total number of students on the y-axis. 
And the curve that you see is basically 
the progression in the points awarded 
week by week. 
And so the goal of course is to push this 
line, this blue line, the dark blue line. 
You know, up and up and up so that we 
stay above these lines. 
The one, two, three, four, five of the 
various, the, the various assignments. 
we are at the TSP now, which is probably 
the most, you know, I think we've just 
finished, the, the hardest part. 
Part of the class where [UNKNOWN] 
location is, is, is easier. 
There are some twists you know, there are 
some really interesting things in 
[UNKNOWN] locations. 
But, but it's easier from a, from a 
programming standpoint that, than that 
the graph coloring in and the TSB 
assignments. 
So in a sense I think we have this hope 
that this, blue curve is going to go up 
and stay above threshold and, and you 
know, we need you obviously to actually 
fulfill that dream. 
So keep working, keep working, guys. 
another thing that was interesting here 
was what happened with the knapsack 
assignment. 
You see there are this, this big jumps, 
that is, big, discontinuities for the 
knapsack, and that's where people got 
stuck and then gave up. 
And what we are, what we are not seeing, 
we are not seeing that now, at this point 
for the rest, so this is much smoother, 
and hopefully that means that we will be 
able to have that curve and keep it above 
the 1,000 mark. 
So, you know interesting statistics. 
You know, we were kind of surprised to 
see that. 
this is the VRP assignment update that I 
mentioned to you. 
essentially, you know, it's telling you 
ten points, you know, the number of 
points that you, you would get. 
you would need before to get to get ten 
points and a number afterwards. 
So I think it's, it's basically it's 
basically lowering a little bit the 
standards. 
Because we were really, really demanding, 
and so everything is being re-graded. 
So you can, yo can look at your score now 
and, and see these changes that we have 
done. 
it's too, it's, you know, it's, it's too 
very difficult to get a 10 point on this, 
on this bench mark, on this, on this 
assignment, but it's a little bit easier 
than it used to be. 
So what's next? 
I think you know, keep up the steady 
progress on the assignments, you know 
keep up the great work. 
You know put, move this curve up above 
the thresholds, and next week, one of the 
things we'll do is review the mid-course 
survey and tell you a little bit what the 
feedback is in the class. 
So keep up the amazing optimizations. 
I'll see you next week, and I'll be back 
in Australia. 
So I'll, you know, you'll see me again, 
and hopefully I'll be, you know, it's not 
going to be too painful to watch me. 
Okay guys. 
Thank you very much. 
Talk to you soon. 
Bye.