Week 8: Assignment 2 and Big-Oh

-The tutorial goes on well as usual. Adam does a really good job as a successor of Yana. He explains things in an easy and efficient way.

-It takes me a while to understand the entire meaning of the Big-Oh expression. Besides, I still have a little doubt about the part "produce non-negative real numbers as output". What I wonder is, certain functions can produce negative numbers as output with natural numbers as input, such as n^2-3n or n^2+n-5, if we take n=1. I should really talk over this with Prof Heap or Adam sometimes.

-Assignment 2 is not difficult, but it definitely requires a whole bunch of carefulness to finish it flawlessly. Although I have checked it several times, I am still afraid about some mistaks in format (e.g. indentation) and in detailed proof.