Sets and Strings

Question 1

Does order matter for substrings and subsets?

Answer 1

Order matters in substring but not subsets

Question 2

How to calculate number of subset?

Answer 2

2^n where n is the length of the set

Question 3

Does empty characters matter in strings?

Answer 3

No

Question 4

Number of substring?

Answer 4

n(n+1)/2

Question 5

Does order and repetition matter in sets?

Answer 5

No

Question 6

Size of a set

Answer 6

A set has size n if it contains n different elements

Question 7

Subsets (⊆)

Answer 7

Let U be a set. Then any collection of element of U is a subset of U

Question 8

(∪)

Answer 8

The Union Let U and V be two sets. The the union of U and V is the set consisting of all elements of U and all strings of V. (Its like adding the two sets together)

Question 9

(∩)

Answer 9

The intersection. Let X and Y be two sets. The intersection is X and Y is the collection of all elements which lie in both sets

Question 10

The difference ()

Answer 10

Let L1, L2 be pair of sets. We define the difference of these two sets, written L1\L2 to be the collection of all elements that are in L1 and not in L2 (its like L1 - L2)

Question 11

Equal sets

Answer 11

To show two sets equal, A has to be a subset of B and B has to be a subset of A

Question 12

∣A∣

Answer 12

The size of A