Question

could you guys help me , I got a quiz tomorrow on this subject and I wanted to make sure that my solutions for these are good , so I know that understood it , I'll post the solution + question in a sec.

Answer 1

I(x) be " x has an internet connection " , C(x,y) be " x and y have chatted over the internet " and the domain is all the students in your class , I need to use quantifiers to express these statements:

a) jerry does not have an internet connection.

*note: the symbol " - " is negation "
My solution: ∃x -I(x)

b) Rachel has not chatted over the internet with Chelsea.
My solution:∃(x,y) -C(x,y)

c) jan and sharon have never chatted over the internet.
My solution: ∃(x,y) -C(x,y)

d) no one in the class has chatted with bob.
My solution: -∀x ∃y C(x,y)

e) sanjay has chatted with everyone except joseph.
My solution: ∃x∀y C(x,y) , y does not equal to joseph

f) someone in your class does not have an internet connection.
My solution: ∃x-I(x)

g) not everyone in your class has an internet connection.
-∀x I(x)

Answer 2

Help please , :(

Answer 3

Im sorry, I cant help :S

Answer 4

ah , it's ok :D

Answer 5

a. i think -I(jerry)

Answer 6

what's the difference ? I think ∃x is in general which is someone from your class ? right ?

Answer 7

Mustafa are you there ? :D

Answer 8

but here i know who is it

Answer 9

You're right , but I think the point of this question is to know where to use quantifiers , but in this case , is my solution right ?

Answer 10

i think -I(jerry) is right

Answer 11

OK let's leave that last , let's check the others.

Answer 12

b.i think -C(Rachel,Chelsea)

Answer 13

ok let's see c

Answer 14

to c is the same ?

Answer 15

as your solution to b ?

Answer 16

so i think d is going to be -∀x C(x,bob) ,

Answer 17

I think e is going to be : ∀y C(sanjay,y) , y!= joseph

Answer 18

d. i think ∀x -C(x,bob)

Answer 19

oh yeah , I forgot about d :D

Answer 20

f , g are correct

Answer 21

e. ∀x : x not equal Joseph ⇒ C(Sanjay, x)) ∧ ¬C(Sanjay, Joseph)

Answer 22

Thanks so much man ^^