Math Is Fun Forum

genericname

Member

Registered: 2012-05-16

Posts: 52

What does the 'p' in the beginning mean? (Logic/Truth table question)

http://i.imgur.com/qGLc1.png

Hi,
Does it mean that all the P's for that problem are true? The problem is telling me to use a truth table to tell whether or not the statement is true and the 'p' in front put me off.

Last edited by genericname (2012-10-16 05:10:16)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: What does the 'p' in the beginning mean? (Logic/Truth table question)

hi genericname

The notation is a little unclear but compare with

http://www.cs.odu.edu/~toida/nerzic/lev … L/E2L.html

I think

p, p<=>q     means   p and p<=>q

The truth tables agree with p^q and you can only test the equivalence if you can also consider the cases where p is false.

Hope that's right.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: What does the 'p' in the beginning mean? (Logic/Truth table question)

The truth tables agree with p^q and you can only test the equivalence if you can also consider the cases where p is false.

What do you mean by this?

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: What does the 'p' in the beginning mean? (Logic/Truth table question)

Do you know what a truth table is?

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

genericname

Member

Registered: 2012-05-16

Posts: 52

Re: What does the 'p' in the beginning mean? (Logic/Truth table question)

hi genericname

The notation is a little unclear but compare with

http://www.cs.odu.edu/~toida/nerzic/lev … L/E2L.html

I think

p, p<=>q     means   p and p<=>q

The truth tables agree with p^q and you can only test the equivalence if you can also consider the cases where p is false.

Hope that's right.

Bob

So it saying to compare the values of p^q with p<=>q?

p | q | p<=>q | p^q |
0 | 0 |      1    |    0   |
0 | 1 |      0    |    0   |
1 | 0 |      0    |    0   |
1 | 1 |      1    |    1   |

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: What does the 'p' in the beginning mean? (Logic/Truth table question)

hi genericname

The truth table below shows what I did.  I'm not saying it is correct; to tell the truth that comma has me puzzled too.  I'd prefer all compound statements to be made using only propostional calculus notation.

Have a look back at your notes / text book.  What is a comma supposed to mean?

If you take a look at that link I gave you, you'll find the author uses two different notations:

notation 1

statement 1
statement 2 underneath

notation 2

statement 1 & statement 2

I assumed that the comma was the equivalent of notation 1.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

genericname

Member

Registered: 2012-05-16

Posts: 52

Re: What does the 'p' in the beginning mean? (Logic/Truth table question)

Thanks, Bob.

Last edited by genericname (2012-10-16 07:31:37)