选择题 20 分
10 题多选题
1, Let B={ø}, A =ρ(ρ(B)), find the correct ones in following statements:
(1) Ø∈A (2) {Ø,{ Ø }}∈A (3) {Ø,{{Ø}}∈A (4) {Ø,{{Ø}} A
2, Let R be a relation on A={1,2,3,…,10}, R={(x,y)|x+y = 10, x,y∈A}, then R is:
(1) reflexive (2) symmetric (3) transitive (4) antisymmetric
3, Let |A| = n, how many binary operations can we define on A:
(1) 2
n
(2) n
2
(3) n
(4) n
4, operation defined as following, which ones can not make ({a,b},*) a monoid?
(1) (2) (3) (4)
5, which ones are lattices in the following posets?
6，Let directed graph D = <V,E>, then:
(1), E V×V (2), E V×V (3) E=V×V (4) V×V E
7, In a connected undirected graph with n vertices, the number of edges is
(1) at least n-1 (2) at least n (3) at most n(n-1)/2 (4) at most n
2
/2
8, which one is tautology?
(1) (P∧(P→Q))→Q (2)P→(P∨Q) (3) P→(P∧Q) （4）(P→Q)→Q
9,In the following sentences, which one is true?
(1), (2),
(3), (4),
10,How many numbers must be chosen from 1 to 25 to ensure that one of
them is a multiple of another?
(1)12 (2)13 (3)14 (4)15
计算题 25 分
(1)
(2) (3) (4)
n
2
2
n
