CE
Ose 1. This shop
232. Напишите по образцу.
(5 4 / 4)
The car is better than the bike. (good)
that shop. (bad)
...? 2. His book
her book. (good)
e's. 3. Our computer
their computer.
(good)
4. The red ball
the black
ball. (bad)
5. Mike's story
Kate's. (good)
29​

Most people have hobbies and interests which they prefer doing in their free time. As for me, I don’t get much free time, especially on weekdays. However, at weekends I try to do the activities I like most of all. They are skating, bowling, dancing, swimming, reading, listening to music and going out with my friends. Ice-skating is something that I have taken up recently and I quite enjoy it. Swimming is my all time favourite activity. For bowling and dancing I need a company. Sometimes me and my friends go to the nearest disco and dance there. The ground floor has bowling alleys, so we can combine these two activities. When I have spare time I love reading books, especially romantic novels and detective stories. When I want something relaxing, I listen to music. My favourite band at the moment is Linkin Park. Occasionally I go for a walk with my best friends. We chat about everything, and sometime we even gossip about other classmates. I plan my weekends in advance. If I don’t have my own plans my friends usually offer me something exciting. Speaking of hobbies, I’d like to tell you about my collection of coins. I collect coins from all over the world. My father often travels and he brings me many different coins. My other hobby is collecting soft toys. I already have more than 50 items. They occupy a special place in my room and my heart. I know that British teenagers have many other leisure activities, such as playing football, horse-riding, taking care of pets, going hiking or to theme parks, and else.

Введем следующие обозначения:

«Это сосуд греческий» — G;
«Это сосуд финикийский» — F;
«Сосуд изготовлен в III веке» — V3;
«Сосуд изготовлен в IV веке» — V4;
«Сосуд изготовлен в V веке» — V5.

Формализуем задачу, записав в данных обозначениях условия задачи.

Со слов учителя следует, что Алеша прав только в чем-то одном: или G = 1, или V5 = 1.

Таким образом, тождественно истинным будет высказывание: GV5 vGV5.=1

Аналогично, из слов Бори и учителя следует: FV3 v FV3 = 1,

а из слов Гриши и учителя: GV4 v GV4 = 1.

Кроме того, ясно, что сосуд может быть изготовлен только в одном из веков и только в одной из стран. Эти условия можно записать так:

V3V4V5 ˅ V3V4V5 ˅ V3V4V5 = 1,

FG v FG = 1.

Итак, мы получили пять тождественно истинных высказываний. Их нужно логически перемножить. Резуль­тат должен быть также тождественно истинным высказыванием:

1 = (GV5 v GV5) & (FV3 v FV3) & (GV4 v GV4) & (FG v FG) &(V3V4V5 ˅ V3V4V5 ˅ V3V4V5) =

 (упростим: сначала перемножим первую и третью скобки и вторую и четвертую скобки)

=(GV5GV4˅GV5GV4 ˅ GV5GV4 ˅ GV5 GV4)&( FV3FG˅FV3 FG˅ FV3 FG ˅ FV3FG) & (V3V4V5 ˅ V3V4V5 ˅ V3V4V5) =

учитывая, что, GG = 0, GG = G, GG = G, упростим выражения в первой и второй скобках:

=(GV5V4 ˅ V5GV4 )&( FV3G ˅V3 FG)& (V3V4V5 ˅ V3V4V5 ˅ V3V4V5) =

(перемножим первую и вторую скобки и упростим полученное выражение)

(GV5V4 FV3G˅V5GV4FV3G˅GV5V4 V3 FG ˅ V5GV4V3FG) & (V3V4V5 ˅ V3V4V5 ˅ (V3V4V5)=(V5V4FV3G˅GV5V4 V3 F) & (V3V4V5 ˅ V3V4V5 ˅ V3V4V5)= GV5V4 V3 F

GV5V4 V3 F=1, если G=1, V5=1, V4 =1, V3=1, F=1

Итак, сосуд финикийский и изготовлен в V веке.