双语离散数学期末考试_2012年春季_试卷A_答案及评分细则.doc

电子科技大学2011-2012学年第 2学期期 末 考试 A 卷 答案及评分细则 课程名称：___离散数学 考试形式： 闭卷 考试日期： 2012 年 月 日 考试时长：_120分钟 Multiple Choice (15%, 1.5 points each) （A ） 1. (?p∧q)→(p∨q) is logically equivalent to a) T b) p∨q c) F d) ?p∧q （B ） 2. If P(A) is the power set of A, and A = ???, what is |P(P(P(A)))|? a) 4 b) 24 c) 28 d) 216 （D ） 3. Which of these statements is NOT a proposition? a) Tomorrow will be Friday. b) 2+3=4. c) There is a dog. d) Go and play with me. （A ） 4. The notation Kn denotes the complete graph on n vertices. Kn is the simple graph that contains exactly one edge between each pair of distinct vertices. How many edges comprise a K20? a) 190 b) 40 c) 95 d) 380 （B ） 5. Suppose ? A ? ? 5 and ? B ? ? 9. The number of injection functions f ? A ? B is a) 45 b) P(9?5). c) 59 d) 95 （B ） 6. Let R be a relation on the positive integers where xRy if x divides y. Which of the following lists of properties best describes the relation R? a) reflexive, symmetric, transitive b) reflexive, antisymmetric, transitive c) reflexive, symmetric, antisymmetric d) symmetric, transitive （C ） 7. Which of the following are partitions of ?? a) ??. b) ? c) ??. d) ? （C ） 8. The function f(x)=3x2log(x3+21) is big-Oof which of the following functions? a) x3 b) x2(logx)3 c) x2logx d) xlogx （A ） 9. In the graph that follows, give an explanation for why there is no path from a back to a that passes through each edge exactly once. a) There are vertices of odd degree, namely {B,D}.b) There are vertices of even degree, namely {A,C}. c) There are vertices of even degree, namely {B,D}. d) There are vertices of odd degree, namely {A,C}. （B ） 10. Which of the followings is a function from Z to R? a) . ` b) . c) d) True or False (10%, 1 point each) （T ） 1. If 3 ? 2, then 7 ? 6. （F ） 2. p ∧