2020年电大离散数学作业3答案资料必考重点(集合论部分).doc
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1、精选 形成性考核作业 姓 名: 学 号: 得 分: 教师签名: 离散数学作业3离散数学集合论部分形成性考核书面作业本课程形成性考核书面作业共3次,内容主要分别是集合论部分、图论部分、数理逻辑部分的综合练习,基本上是按照考试的题型(除单项选择题外)安排练习题目,目的是通过综合性书面作业,使同学自己检验学习成果,找出掌握的薄弱知识点,重点复习,争取尽快掌握。本次形考书面作业是第一次作业,大家要认真及时地完成集合论部分的综合练习作业。要求:将此作业用A4纸打印出来,手工书写答题,字迹工整,解答题要有解答过程,要求2010年11月7日前完成并上交任课教师(不收电子稿)。并在03任务界面下方点击“保存”
2、和“交卷”按钮,完成并上交任课教师。一、填空题 1设集合,则P(A)-P(B )= 1,2,2,3,1,3,1,2,3 ,A B= , 2设集合A有10个元素,那么A的幂集合P(A)的元素个数为 1024 3设集合A=0, 1, 2, 3,B=2, 3, 4, 5,R是A到B的二元关系,则R的有序对集合为 ,4设集合A=1, 2, 3, 4 ,B=6, 8, 12, A到B的二元关系R那么R1 , 5设集合A=a, b, c, d,A上的二元关系R=, , , ,则R具有的性质是反自反性6设集合A=a, b, c, d,A上的二元关系R=, , , ,若在R中再增加两个元素, ,则新得到的关系
3、就具有对称性7如果R1和R2是A上的自反关系,则R1R2,R1R2,R1-R2中自反关系有 2 个8设A=1, 2上的二元关系为R=|xA,yA, x+y =10,则R的自反闭包为 , 9设R是集合A上的等价关系,且1 , 2 , 3是A中的元素,则R中至少包含 , 等元素10设集合A=1, 2,B=a, b,那么集合A到B的双射函数是 ,或, 二、判断说明题(判断下列各题,并说明理由)1若集合A = 1,2,3上的二元关系R=,则(1) R是自反的关系; (2) R是对称的关系 解:(1) 结论不成立 因为关系R要成为自反的,其中缺少元素 (2) 结论不成立 因为关系R中缺少元素 2如果R1
4、和R2是A上的自反关系,判断结论:“R-11、R1R2、R1R2是自反的” 是否成立?并说明理由 解:结论成立 因为R1和R2是A上的自反关系,即IAR1,IAR2 由逆关系定义和IAR1,得IA R1-1; 由IAR1,IAR2,得IA R1R2,IA R1R2所以,R1-1、R1R2、R1R2是自反的ooooabcd图一ooogefho3若偏序集的哈斯图如图一所示,则集合A的最大元为a,最小元不存在 错误,按照定义,图中不存在最大元和最小元。 4设集合A=1, 2, 3, 4,B=2, 4, 6, 8,判断下列关系f是否构成函数f:,并说明理由(1) f=, , , ; (2)f=, ,
5、;(3) f=, , , (1) 不构成函数,因为它的定义域Dom(f)A(2) 也不构成函数,因为它的定义域Dom(f)A(3) 构成函数,首先它的定义域Dom(f) =1, 2, 3, 4= A,其次对于A中的每一个元素a,在B中都有一个唯一的元素b,使f三、计算题1设,求:(1) (AB)C; (2) (AB)- (BA) (3) P(A)P(C); (4) AB解:(1) (AB)C=11,3,5=1,3,5(2) (AB)- (BA)=1,2,4,5-1=2,4,5(3) P(A) =,1,4,1,4P(C)= ,2,4,2,4P(A)P(C)=1,1,4(4) AB= (AB)-
6、(BA)= 2,4,52设A=1,2,1,2,B=1,2,1,2,试计算(1)(A-B); (2)(AB); (3)AB解:(1)(A-B)=1,2(2)(AB)=1,2(3) AB ,3设A=1,2,3,4,5,R=|xA,yA且x+y4,S=|xA,yA且x+y0,试求R,S,RS,SR,R-1,S-1,r(S),s(R) 解: R=,S=RS=SR=R-1=,S-1=r(S)= ,s(R)= , 4设A=1, 2, 3, 4, 5, 6, 7, 8,R是A上的整除关系,B=2, 4, 6(1) 写出关系R的表示式; (2 )画出关系R的哈斯图; (3) 求出集合B的最大元、最小元 解:(
7、1) R=,12346578关系R的哈斯图(2) (3) 集合B没有最大元,最小元是2四、证明题 1试证明集合等式:A (BC)=(AB) (AC)证:设,若xA (BC),则xA或xBC,即 xA或xB 且 xA或xC即xAB 且 xAC ,即 xT=(AB) (AC),所以A (BC) (AB) (AC) 反之,若x(AB) (AC),则xAB 且 xAC, 即xA或xB 且 xA或xC,即xA或xBC,即xA (BC),所以(AB) (AC) A (BC) 因此A (BC)=(AB) (AC)2试证明集合等式A (BC)=(AB) (AC)证明:设S=A(BC),T=(AB)(AC),
8、若xS,则xA且xBC,即 xA且xB 或 xA且xC, 也即xAB 或 xAC ,即 xT,所以ST 反之,若xT,则xAB 或 xAC, 即xA且xB 或 xA且xC 也即xA且xBC,即xS,所以TS 因此T=S 3对任意三个集合A, B和C,试证明:若AB = AC,且A,则B = C 证明:设xA,yB,则AB, 因为AB = AC,故 AC,则有yC, 所以B C 设xA,zC,则 AC, 因为AB = AC,故AB,则有zB,所以CB 故得A=B 4试证明:若R与S是集合A上的自反关系,则RS也是集合A上的自反关系R1和R2是自反的,x A, R1, R2,则 R1R2, 所以R
9、1R2是自反的请您删除一下内容,O(_)O谢谢!【Chinas 10 must-see animations】The Chinese animation industry has seen considerable growth in the last several years. It went through a golden age in the late 1970s and 1980s when successively brilliant animation work was produced. Here are 10 must-see classics from Chinas an
10、imation outpouring that are not to be missed. Lets recall these colorful images that brought the country great joy. Calabash Brothers Calabash Brothers (Chinese: 葫芦娃) is a Chinese animation TV series produced byShanghaiAnimationFilmStudio. In the 1980s the series was one of the most popular animatio
11、ns in China. It was released at a point when the Chinese animation industry was in a relatively downed state compared to the rest of the international community. Still, the series was translated into 7 different languages. The episodes were produced with a vast amount of paper-cut animations. Black
12、Cat Detective Black Cat Detective (Chinese: 黑猫警长) is a Chinese animation television series produced by the Shanghai Animation Film Studio. It is sometimes known as Mr. Black. The series was originally aired from 1984 to 1987. In June 2006, a rebroadcasting of the original series was announced. Criti
13、cs bemoan the series violence, and lack of suitability for childrens education. Proponents of the show claim that it is merely for entertainment. Effendi Effendi, meaning sir andteacher in Turkish, is the respectful name for people who own wisdom and knowledge. The heros real name was Nasreddin. He
14、was wise and witty and, more importantly, he had the courage to resist the exploitation of noblemen. He was also full of compassion and tried his best to help poor people. Adventure of Shuke and Beita【舒克与贝塔】 Adventure of Shuke and Beita (Chinese: 舒克和贝塔) is a classic animation by Zheng Yuanjie, who i
15、s known as King of Fairy Tales in China. Shuke and Beita are two mice who dont want to steal food like other mice. Shuke became a pilot and Beita became a tank driver, and the pair met accidentally and became good friends. Then they befriended a boy named Pipilu. With the help of PiPilu, they co-fou
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