电大离散数学(本)7月试题解答（小抄参考）

1、试卷代号：1009 座位号 中央广播电视大学20102011学年度第一学期“开放本科”期末考试离散数学（本）试题解答2011年 7月 (供参考)一、单项选择题（每小题3分，本题共15分）1a 2c 3c 4d 5b二、填空题（每小题3分，本题共15分）6真（或t，或1）7e+18g是连通的且结点度数都是偶数910x三、逻辑公式翻译（每小题6分，本题共12分）11设p：雪是黑色的， （2分）则命题公式为：p （6分）12设 p：如果明天下雨， q：我们在室内上体育课， （2分）则命题公式为：p q （6分）四、判断说明题（每小题7分，本题共14分）13错误 （3分）因为a中元素1有b中两个不同的

2、元素与之对应，故f不是a到b的函数 （7分）14正确 （3分）因g是一个连通平面图，满足欧拉定理，有v-e+r=2，所以r=2-（v-e）=2-（5-9）=6 （7分）五计算题（每小题12分，本题共36分）15p（rq）p（rq） （6分） (pr) （pq）（合取范式） （12分） 16（1）（ab）=1 （4分） （2）（ab）=1, 2, 1, 2, 1, 2 （8分） （3）（ab）-a = （12分）ooooooooo23345510717 17最优二叉树如图二所示 （10分） 图二 权为23+33+32+42+52=39 （12分） 六、证明题（本题共8分） 18证明：设x，ya，

3、因为r对称，所以若r，则r （2分） 因为s对称，所以若s，则s （4分） 于是若rs 则r且s 即 r且s （6分） 也即 rs，故rs是对称的 （8分）if we dont do that it will go on and go on. we have to stop it; we need the courage to do it.his comments came hours after fifa vice-president jeffrey webb - also in london for the fas celebrations - said he wanted to meet

4、 ivory coast international toure to discuss his complaint.cska general director roman babaev says the matter has been exaggerated by the ivorian and the british media.blatter, 77, said: it has been decided by the fifa congress that it is a nonsense for racism to be dealt with with fines. you can alw

5、ays find money from somebody to pay them.it is a nonsense to have matches played without spectators because it is against the spirit of football and against the visiting team. it is all nonsense.we can do something better to fight racism and discrimination.this is one of the villains we have today i

6、n our game. but it is only with harsh sanctions that racism and discrimination can be washed out of football.the (lack of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend

7、 citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya toure, he told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskaf

8、or the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footballs governing body, has also ordered an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: w

9、e found no racist insults from fans of cska.baumgartner the disappointing news: mission aborted.the supersonic descent could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipit

10、ation or humidity and limited cloud cover. the balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruis

11、ing altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out ont

12、o something resembling an olympic diving platform.below, the earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. it will be like he is diving i

13、nto the shallow end.skydiver preps for the big jumpwhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to earth. but this will not be enough to s

14、top him completely.if he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. his team hopes its not needed. instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).in order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). he will have a reserve parachute that will open automatically if he loses consciousness at m