# Probability of AᴧBᴧBᴧC equal zero why 1

1. Oct 12, 2012

probability of AᴧBᴧBᴧC equal zero why!!1

(B v AE)ᴧ( Ev C)
So after multiplication you should have
AᴧBᴧBᴧC
But he didnt mention this, so it should by zero ,but why!!!!!!!!!!!!!!11

2. Oct 12, 2012

### chiro

Re: probability of AᴧBᴧBᴧC equal zero why!!1

What does the E refer to?

3. Oct 13, 2012

Re: probability of AᴧBᴧBᴧC equal zero why!!1

All the symbol are probability of events

4. Oct 13, 2012

### haruspex

Re: probability of AᴧBᴧBᴧC equal zero why!!1

Sadeq, several things need more explanation.
You have written AE with no symbol in between. What does this mean?
If A and B are probabilities, what does A v B mean? Surely they events, not the probabilities of the events?
On my device, the other symbol you use shows up as a square. Is this an AND symbol?
I don't understand the steps in your multiplication. What happened to E?

5. Oct 13, 2012

Re: probability of AᴧBᴧBᴧC equal zero why!!1

Im so sorry ,i was in hurry when i wrote this, so sorry
I upload the a picture for the problem ,when you look at the picture u will see, two yellow terms,which eventually will have to multiply them togethor,so all symbols will be in Intersection(4 symbols),
So my question why the answer is zero, since nothing come on the result from those terms

#### Attached Files:

• ###### ssss.PNG
File size:
20.1 KB
Views:
142
6. Oct 13, 2012

### haruspex

Re: probability of AᴧBᴧBᴧC equal zero why!!1

OK, I've read the attachment and it all makes sense, so long as the AND operation is defined as more binding than OR. So what is it you don't understand? What is it that appears to be zero?

7. Oct 13, 2012

Re: probability of AᴧBᴧBᴧC equal zero why!!1

AᴧEᴧC= disappear from answer
Why

8. Oct 13, 2012

### haruspex

Re: probability of AᴧBᴧBᴧC equal zero why!!1

Becausd it is subsumed by A & C. In general, X v (X & Y) = X.

9. Oct 13, 2012

Re: probability of AᴧBᴧBᴧC equal zero why!!1

could u please explain a little bit more please
im sorry i took a lot from your time

10. Oct 13, 2012

### haruspex

Re: probability of AᴧBᴧBᴧC equal zero why!!1

In the expression X v (X & Y):
Suppose X is true. Then the whole expression is true.
Suppose X is false. Then both sides of the OR are false, so the expression is false.
Therefore the expression is equivalent to just X.
Likewise, X & (X v Y) reduces to X.

11. Oct 15, 2012