In these week lecture, we learned about the sorting strategies, using an example of ordering a deck of cards from largest to the smallest. we have insertion sort , selection sort and other more complicate sorts such as Radix, Quick sort, Tim, Merge sort.
we always think about the worst case in sorting or counting costs.
We also talks about how to disprove a implication, which maybe useful in A2
conjunction elimination: when A and B is True ,then both A B is true. If A and B is false, then at least one of them is false.
existential instantiation: we just need one example
disjunction elimination: If we know A or B is true ,while A is false ,we certainly know that B must me true
implication elimination: When A implies B, if A is true, then B must me true. (know A then know B)If not B is true, then not A must be true.
universal elimination: if there exists one x that is not P(x), then the universal statement will be false
we always think about the worst case in sorting or counting costs.
We also talks about how to disprove a implication, which maybe useful in A2
conjunction elimination: when A and B is True ,then both A B is true. If A and B is false, then at least one of them is false.
existential instantiation: we just need one example
disjunction elimination: If we know A or B is true ,while A is false ,we certainly know that B must me true
implication elimination: When A implies B, if A is true, then B must me true. (know A then know B)If not B is true, then not A must be true.
universal elimination: if there exists one x that is not P(x), then the universal statement will be false
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