week 7

In this week, since we are working on the assignment 2, I have some thoughts about proving structure in general:

    first of all, if it is a universal quantifier, then you assume an general element which meets the requires, then prove it by assuming the first part of the implication True and using the condition to transfer to a statement which is the latter part of the implication.

    Secondly, if it is an existential quantifier(most the case it is in a disproof), then you pick a element that satisfies the implication. After all these, you have proved a negation of an original statement.

Moreover, we learn some sorting algorithms and how to count the steps. Most of the case, we are consider the worst case of an sorting algorithm and after all the constant in front of the number of steps is not that important anymore.